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J. Compos. Sci.
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Theoretical and Computational Investigation on Composite Materials
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Theoretical and Computational Investigation on Composite Materials

A special issue of Journal of Composites Science (ISSN 2504-477X). This special issue belongs to the section "Composites Modelling and Characterization".

Deadline for manuscript submissions: 15 February 2026 | Viewed by 33353

Special Issue Editor

Prof. Dr. Zhong Hu

E-Mail Website
Guest Editor
Department of Mechanical Engineering, South Dakota State University, Brookings, SD, USA
Interests: multi-scale material modeling and characterization; design of composites and nano-composites; characterization of materials/composites/nanostructured thin films and coatings; mechanical strength evaluation and failure prediction; metal forming processing design/testing/modeling/optimization
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Given the rapid development of composite materials science and technology, there is a need to understand their structure, properties, and the integration of structure–property relationships in processing, design, and manufacturing. Traditional trial-and-error experimental approaches are time consuming and expensive. Theoretical analysis and computational modeling of composite materials at different scales is required in the context of increased accuracy in many engineering problems and applications. This Special Issue aims to bring together experts and researchers in theoretical and computational modeling of composite materials, covering topics such as the effects of the reinforcement staking sequence, ply orientation, agglomeration and dispersion of nanoparticles, surface treatment and the functionalization of reinforcements, interfacial interactions between matrix and reinforcement, delamination/debonding and failure, the volume fractions of constituents, the porosity level of composites, etc. This Special Issue also covers various research scales, such as macro-, micro-, nano-, and electronic structures, their macro-mechanics, nano-mechanics, interphase, physical and chemical interaction, and process modeling. It will also cover the interdisciplinary character of subjects and the possible development and use of composites in novel and specific applications.

Topics include but are not limited to:

Classical and high-performance advanced theories and multiscale approaches (including but not limited to quantum mechanics or ab initio modeling, molecular dynamics, meso-mechanics modeling, and finite element analysis).

Composite materials to be studied include but are not limited to continuous/discontinuous fiber-reinforced composites and laminates, nanoparticle or nanofiber modified composites, functionalized composites, carbon nanotubes (CNTs), graphene nanoplatelets, and innovative and advanced classes of composites.

Prof. Dr. Zhong Hu
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Journal of Composites Science is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • quantum mechanics modeling
  • molecular dynamics
  • finite element analysis
  • computer modeling
  • multiscale modeling
  • theoretical analysis
  • composite materials
  • polymer composites
  • material properties
  • composites design

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Published Papers (26 papers)

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21 pages, 11401 KiB  
Article
Numerical Analysis of the Cyclic Behavior of Reinforced Concrete Columns Incorporating Rubber
by Mohammed A. M. Ahmed, Heba A. Mohamed, Hilal Hassan, Ayman El-Zohairy and Mohamed Emara
J. Compos. Sci. 2025, 9(3), 95; https://doi.org/10.3390/jcs9030095 - 21 Feb 2025
Viewed by 132
Abstract
A numerical analysis of rubberized reinforced concrete columns’ performance under cyclic loading is presented in this study. Three different concrete blends (M1, M2, and M3) were chosen based on the volume of fine aggregate replaced by varying percentages of crumb rubber (CR) (0%, [...] Read more.
A numerical analysis of rubberized reinforced concrete columns’ performance under cyclic loading is presented in this study. Three different concrete blends (M1, M2, and M3) were chosen based on the volume of fine aggregate replaced by varying percentages of crumb rubber (CR) (0%, 10%, and 15%). Under cyclic loads, three groups of rubberized reinforced concrete (RRC) columns with circular, square, and rectangular cross-sections and heights of 1.5 m and 2.0 m were analyzed using the finite element software ABAQUS. The proposed model effectively predicts the behavior of rubberized reinforced concrete columns under cyclic loading. Additionally, these columns demonstrate improved performance in lateral displacement, displacement ductility, and damping ratio, with only a slight reduction in lateral load capacity. For the circular columns with a height of 1.5 m, the displacement ductility increased by 47.8% and 89.0% when the fine aggregates were replaced with 10% and 15% CR, respectively. Similarly, for square columns of the same height, the displacement ductility increased by 18.7% and 26.7% with 10% and 15% CR, respectively. The rectangular specimens exhibited enhancements of 34.74% and 58.95%, respectively. Although the analyzed rubberized reinforced concrete columns experienced slight reductions in the lateral load capacity compared to the non-CR columns, the cyclic damage resistance was notably improved. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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Figure 1

Figure 1
<p>Details of the circular columns of Group 1.</p> Full article ">Figure 2
<p>Details of the square columns of Group 2.</p> Full article ">Figure 3
<p>Details of the rectangular columns of Group 3.</p> Full article ">Figure 4
<p>Crumb rubber particles [<a href="#B18-jcs-09-00095" class="html-bibr">18</a>].</p> Full article ">Figure 5
<p>Effects of CR on the mechanical properties of concrete.</p> Full article ">Figure 6
<p>Concrete damage plasticity model provided by ABAQUS [<a href="#B18-jcs-09-00095" class="html-bibr">18</a>].</p> Full article ">Figure 7
<p>FE simulation utilizes constitutive models of materials [<a href="#B18-jcs-09-00095" class="html-bibr">18</a>].</p> Full article ">Figure 8
<p>The loading protocol [<a href="#B22-jcs-09-00095" class="html-bibr">22</a>].</p> Full article ">Figure 9
<p>Loading and boundary conditions of the FE models. These arrows represent the directions of the axial load and lateral displacement, which are provided on the figure.</p> Full article ">Figure 10
<p>RC column details [<a href="#B22-jcs-09-00095" class="html-bibr">22</a>].</p> Full article ">Figure 11
<p>Results of experimental and FEM RC column.</p> Full article ">Figure 12
<p>RRC column details.</p> Full article ">Figure 13
<p>Results of the experimental and FE results for the analyzed RRC column.</p> Full article ">Figure 14
<p>Hysteretic behavior of circular columns (Group 1).</p> Full article ">Figure 15
<p>Hysteretic behavior of square columns (Group 2).</p> Full article ">Figure 16
<p>Hysteretic behavior of rectangular columns (Group 3).</p> Full article ">Figure 17
<p>Backbone curve for columns.</p> Full article ">Figure 18
<p>Equivalent viscous damping and displacement ductility of columns.</p> Full article ">Figure 19
<p>Effect of crumb rubber on equivalent viscous damping and displacement ductility of columns.</p> Full article ">
17 pages, 4583 KiB  
Article
Numerical Analysis and Life Cycle Assessment of Type V Hydrogen Pressure Vessels
by Mohd Shahneel Saharudin, Syafawati Hasbi, Santosh Kumar Sahu, Quanjin Ma and Muhammad Younas
J. Compos. Sci. 2025, 9(2), 75; https://doi.org/10.3390/jcs9020075 - 7 Feb 2025
Viewed by 818
Abstract
The growing concern about greenhouse gas emissions and global warming has heightened the focus on sustainability across industrial sectors. As a result, hydrogen energy has emerged as a versatile and promising solution for various engineering applications. Among its storage options, Type V composite [...] Read more.
The growing concern about greenhouse gas emissions and global warming has heightened the focus on sustainability across industrial sectors. As a result, hydrogen energy has emerged as a versatile and promising solution for various engineering applications. Among its storage options, Type V composite pressure vessels are particularly attractive because they eliminate the need for a polymer liner during manufacturing, significantly reducing material usage and enhancing their environmental benefit. However, limited research has explored the pressure performance and life cycle assessment of these vessels. To address this gap, this study investigates the pressure performance and carbon emissions of a Type V hydrogen pressure vessel using four composite materials: Kevlar/Epoxy, Basalt/Epoxy, E-Glass/Epoxy, and Carbon T-700/Epoxy. The results reveal that Carbon T-700/Epoxy is the most suitable material for high-pressure hydrogen storage due to its superior mechanical properties, including the highest burst pressure, maximum stress capacity, and minimal deformation under loading. Conversely, the LCA results, supported by insights from a large language model (LLM), show that Basalt/Epoxy provides a more sustainable option, exhibiting notably lower global warming potential (GWP) and acidification potential (AP). These findings highlight the trade-offs between mechanical performance and environmental impact, offering valuable insights for sustainable hydrogen storage design. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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Figure 1

Figure 1
<p>Geometry (<b>a</b>) and the isometric view (<b>b</b>) of the pressure vessel used in this study.</p> Full article ">Figure 2
<p>Mesh dependency study.</p> Full article ">Figure 3
<p>Boundary conditions on the pressure vessel.</p> Full article ">Figure 4
<p>The comparison of deformation between the theoretical calculations and simulation results reveals minimal differences, indicating strong agreement between the two approaches.</p> Full article ">Figure 5
<p>Top view of the hydrogen pressure vessel (no wireframe). The colour scale represents the stress distribution, where red indicates the maximum stress and blue represents the minimum stress, with a gradient transition through yellow and green.</p> Full article ">Figure 6
<p>Sectional plane view of the Carbon T-700/Epoxy hydrogen pressure vessel. The colour scale represents the stress distribution, where red indicates the maximum stress and blue represents the minimum stress, with a gradient transition through yellow and green.</p> Full article ">Figure 7
<p>Stacking sequence of the composites used in this study. The arrow shows the sequence in which the composite plies are stacked, moving from bottom to top.</p> Full article ">Figure 8
<p>Flow chart of LLM to evaluate the environmental impact in this study.</p> Full article ">Figure 9
<p>Comparison of burst pressure and allowable working pressure for different material types.</p> Full article ">Figure 10
<p>Maximum principal stress vs. pressure for different materials.</p> Full article ">Figure 11
<p>Maximum equivalent stress vs. pressure for different materials.</p> Full article ">Figure 12
<p>Equivalent elastic strain vs. pressure for different materials.</p> Full article ">Figure 13
<p>Maximum principal elastic strain vs. pressure for different materials.</p> Full article ">Figure 14
<p>Global warming potential based on fibre production, resin production, aluminium boss, polyethylene coating, manufacturing, and transportation.</p> Full article ">Figure 15
<p>Acidification potential from fibre production, resin curing, aluminium, and transportation.</p> Full article ">Figure 16
<p>Photochemical ozone creation potential (POCP) from epoxy curing (VOCs) and NOₓ from transportation.</p> Full article ">Figure 17
<p>Particulate matter formation.</p> Full article ">
18 pages, 3979 KiB  
Article
Assessment of Wear and Surface Roughness Characteristics of Polylactic Acid (PLA)—Graphene 3D-Printed Composites by Box–Behnken Method
by Manjunath G. Avalappa, Vaibhav R. Chate, Nikhil Rangaswamy, Shriranganath P. Avadhani, Ganesh R. Chate and Manjunath Shettar
J. Compos. Sci. 2025, 9(1), 1; https://doi.org/10.3390/jcs9010001 - 24 Dec 2024
Viewed by 745
Abstract
The biodegradability and comparatively less harmful degradation of polylectic acid (PLA) make it an appealing material in many applications. The composite material is used as a feed for a 3D printer, consisting of PLA as a matrix and graphene (3 wt.%) as reinforcement. [...] Read more.
The biodegradability and comparatively less harmful degradation of polylectic acid (PLA) make it an appealing material in many applications. The composite material is used as a feed for a 3D printer, consisting of PLA as a matrix and graphene (3 wt.%) as reinforcement. The composite is extruded in the form of wires using a screw-type extruder machine. Thus, prepared wire is used to 3D print the specimens using fused deposition modeling (FDM) type additive manufacturing technology. The specimens are prepared by varying the different process parameters of the FDM machine. This study’s primary objective is to understand the tribological phenomena and surface roughness of PLA reinforced with graphene. Initially, pilot experiments are conducted to screen essential factors of the FDM machine and decide the levels that affect the response variables, such as surface roughness and wear. The three factors, viz., layer height, printing temperature, and printing speed, are considered. Further experiments and analysis are conducted using the Box–Beheken method to study the tribological behavior of 3D-printed composites and the effect of these parameters on surface roughness and wear loss. It is interesting to note that layer height is significant for surface roughness and wear loss. The optimum setting for minimum surface roughness is layer height at 0.16 mm, printing temperature at 180 °C, and printing speed at 60 mm/s. The optimum setting for minimum wear loss is layer height at 0.24 mm, printing temperature at 220 °C, and printing speed at 90 mm/s. The desirability function approach is used to optimize (multiobjective optimization) both surface roughness and wear loss. The layer height of 0.16 mm, printing temperature of 208 °C, and printing speed of 90 mm/s are the optimum levels for a lower surface roughness and wear loss. The SEM images reveal various wear mechanisms, viz., abrasive grooves, micro-fractures, and the presence of wear debris. The work carried out helps to make automobile door panels since they undergo wear due to excessive friction, aging, material degradation, and temperature fluctuations. These are taken care of by graphene addition in PLA with an optimized printing process, and a good surface finish helps with proper assembly. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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Figure 1

Figure 1
<p>Flow chart of methodology.</p> Full article ">Figure 2
<p>Three-Dimensional Printing Process.</p> Full article ">Figure 3
<p>(<b>a</b>) Wear and Surface Roughness Testing Specimen; (<b>b</b>) Prepared Specimens.</p> Full article ">Figure 4
<p>Mitutoyo Model SJ-410 Portable Surface Roughness Tester.</p> Full article ">Figure 5
<p>Main effect plots for surface roughness.</p> Full article ">Figure 6
<p>Interaction Plots for Surface roughness.</p> Full article ">Figure 7
<p>Three-dimensional surface plots for (<b>a</b>) layer height, printing temperature v/s surface roughness; (<b>b</b>) layer height, printing speed v/s surface roughness; (<b>c</b>) printing speed, printing temperature v/s surface roughness.</p> Full article ">Figure 8
<p>Contour plots for surface roughness: (<b>a</b>) layer height and printing temperature; (<b>b</b>) layer height and printing speed; (<b>c</b>) printing temperature and printing speed.</p> Full article ">Figure 9
<p>Main effect plots for wear loss.</p> Full article ">Figure 10
<p>Interaction plots for wear loss.</p> Full article ">Figure 11
<p>Three-dimensional surface plots for (<b>a</b>) layer height, printing temperature v/s surface roughness, (<b>b</b>) layer height, printing speed v/s surface roughness, (<b>c</b>) printing speed, printing temperature v/s surface roughness.</p> Full article ">Figure 12
<p>Contour plots for wear loss (<b>a</b>) layer height and printing temperature (<b>b</b>) layer height and printing speed (<b>c</b>) printing temperature and printing speed.</p> Full article ">Figure 13
<p>SEM images of worn surfaces. (<b>a</b>) Worn surface of specimen produced at A3, B3, and C3; (<b>b</b>) Worn surface of specimen produced at A1, B1, and C2; (<b>c</b>) Worn surface of specimen produced at A—0.16 mm, B—208 °C, C—90 mm/s.</p> Full article ">Figure 13 Cont.
<p>SEM images of worn surfaces. (<b>a</b>) Worn surface of specimen produced at A3, B3, and C3; (<b>b</b>) Worn surface of specimen produced at A1, B1, and C2; (<b>c</b>) Worn surface of specimen produced at A—0.16 mm, B—208 °C, C—90 mm/s.</p> Full article ">
21 pages, 6455 KiB  
Article
Determination of Crack Depth in Brickworks by Ultrasonic Methods: Numerical Simulation and Regression Analysis
by Alexey N. Beskopylny, Sergey A. Stel’makh, Evgenii M. Shcherban’, Vasilii Dolgov, Irina Razveeva, Nikita Beskopylny, Diana Elshaeva and Andrei Chernil’nik
J. Compos. Sci. 2024, 8(12), 536; https://doi.org/10.3390/jcs8120536 - 16 Dec 2024
Viewed by 850
Abstract
Ultrasonic crack detection is one of the effective non-destructive methods of structural health monitoring (SHM) of buildings and structures. Despite its widespread use, crack detection in porous and heterogeneous composite building materials is an insufficiently studied issue and in practice leads to significant [...] Read more.
Ultrasonic crack detection is one of the effective non-destructive methods of structural health monitoring (SHM) of buildings and structures. Despite its widespread use, crack detection in porous and heterogeneous composite building materials is an insufficiently studied issue and in practice leads to significant errors of more than 40%. The purpose of this article is to study the processes occurring in ceramic bricks weakened by cracks under ultrasonic exposure and to develop a method for determining the crack depth based on the characteristics of the obtained ultrasonic response. At the first stage, the interaction of the ultrasonic signal with the crack and the features of the pulse propagation process in ceramic bricks were considered using numerical modeling with the ANSYS environment. The FEM model allowed us to identify the characteristic aspects of wave propagation in bricks and compare the solution with the experimental one for the reference sample. Further experimental studies were carried out on ceramic bricks, as the most common elements of buildings and structures. A total of 110 bricks with different properties were selected. The cracks were natural or artificially created and were of varying depth and width. The experimental data showed that the greatest influence on the formation of the signal was exerted by the time parameters of the response: the time when the signal reaches a value of 12 units, the time of reaching the first maximum, the time of reaching the first minimum, and the properties of the material. Based on the regression analysis, a model was obtained that relates the crack depth to the signal parameters and the properties of the material. The error in the predicted values according to this model was approximately 8%, which was significantly more accurate than the existing approach. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
►▼ Show Figures

Figure 1

Figure 1
<p>Appearance of experimental samples of bricks with cracks of different depths.</p> Full article ">Figure 2
<p>The process of detecting cracks in bricks using the Pulsar-2.2 ultrasonic device.</p> Full article ">Figure 3
<p>Scheme of installation of sensors for measuring crack depth.</p> Full article ">Figure 4
<p>General diagram of a block with a crack: 1—point of pulse application; 2—location of the ultrasonic signal receiver.</p> Full article ">Figure 5
<p>Comparison of experimental and numerical simulation results (Plexiglas material is the reference sample).</p> Full article ">Figure 6
<p>Wave propagation in a plexiglass block at the moments of time (<b>a</b>) <span class="html-italic">t</span> = 2 µs, (<b>b</b>) <span class="html-italic">t</span> = 8 µs, (<b>c</b>) <span class="html-italic">t</span> = 16 µs, and (<b>d</b>) <span class="html-italic">t</span> = 30 µs.</p> Full article ">Figure 6 Cont.
<p>Wave propagation in a plexiglass block at the moments of time (<b>a</b>) <span class="html-italic">t</span> = 2 µs, (<b>b</b>) <span class="html-italic">t</span> = 8 µs, (<b>c</b>) <span class="html-italic">t</span> = 16 µs, and (<b>d</b>) <span class="html-italic">t</span> = 30 µs.</p> Full article ">Figure 7
<p>Successive development of von Mises stresses in a brick weakened by a crack at different points in time: (<b>a</b>) <span class="html-italic">t</span> = 9.5 µs, (<b>b</b>) <span class="html-italic">t</span> = 13.5 µs, (<b>c</b>) <span class="html-italic">t</span> = 17.5 µs, (<b>d</b>) <span class="html-italic">t</span> = 21.5 µs, (<b>e</b>) <span class="html-italic">t</span> = 23.5 µs, and (<b>f</b>) <span class="html-italic">t</span> = 47.5 µs.</p> Full article ">Figure 7 Cont.
<p>Successive development of von Mises stresses in a brick weakened by a crack at different points in time: (<b>a</b>) <span class="html-italic">t</span> = 9.5 µs, (<b>b</b>) <span class="html-italic">t</span> = 13.5 µs, (<b>c</b>) <span class="html-italic">t</span> = 17.5 µs, (<b>d</b>) <span class="html-italic">t</span> = 21.5 µs, (<b>e</b>) <span class="html-italic">t</span> = 23.5 µs, and (<b>f</b>) <span class="html-italic">t</span> = 47.5 µs.</p> Full article ">Figure 7 Cont.
<p>Successive development of von Mises stresses in a brick weakened by a crack at different points in time: (<b>a</b>) <span class="html-italic">t</span> = 9.5 µs, (<b>b</b>) <span class="html-italic">t</span> = 13.5 µs, (<b>c</b>) <span class="html-italic">t</span> = 17.5 µs, (<b>d</b>) <span class="html-italic">t</span> = 21.5 µs, (<b>e</b>) <span class="html-italic">t</span> = 23.5 µs, and (<b>f</b>) <span class="html-italic">t</span> = 47.5 µs.</p> Full article ">Figure 8
<p>Dependence of UY displacements at the receiving point on the pulse propagation time: 1—without defect; 2—crack 20 mm deep; 3—crack 60 mm deep.</p> Full article ">Figure 9
<p>Comparison of ultrasonic pulse signals for different crack depths.</p> Full article ">Figure 10
<p>Characteristic parameters of the signal used to determine the crack depth.</p> Full article ">Figure 11
<p>Experimental and predicted values for averaged parameters.</p> Full article ">Figure 12
<p>Experimental and predicted values for averaged parameters taking into account the material properties.</p> Full article ">
28 pages, 13426 KiB  
Article
Phase Field Modelling of Failure in Thermoset Composites Under Cure-Induced Residual Stress
by Aravind Balaji, David Dumas and Olivier Pierard
J. Compos. Sci. 2024, 8(12), 533; https://doi.org/10.3390/jcs8120533 - 15 Dec 2024
Viewed by 1094
Abstract
This study examines the residual stress induced by manufacturing and its effect on failure in thermosetting unidirectional composites under quasi-static loading, using Finite Element-based computational models. During the curing process, the composite material develops residual stress fields due to various phenomena. These stress [...] Read more.
This study examines the residual stress induced by manufacturing and its effect on failure in thermosetting unidirectional composites under quasi-static loading, using Finite Element-based computational models. During the curing process, the composite material develops residual stress fields due to various phenomena. These stress fields are predicted using a constitutive viscoelastic model and subsequently initialized within a damage-driven Phase Field model. Structural tensors are used to modify the stress-based failure criteria to account for inherent transverse isotropy. This influence is incorporated into the crack phase field evolution equation, enabling a modular framework that retains all residual stress information through a heat-transfer analogy. The proposed coupled computational model is validated through a representative numerical case study involving L-shaped composite parts. The findings reveal that cure-induced residual stresses, in conjunction with discontinuities, play a critical role in matrix cracking and significantly affect the structural load-carrying capacity. The proposed coupled numerical approach provides an initial estimation of the influence of manufacturing defects and streamlines the optimization of cure profiles to enhance manufacturing quality. Among the investigated curing strategies, the three-dwell cure cycle emerged as the most effective solution. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Residually stressed composite lamina, <math display="inline"><semantics> <mrow> <mi mathvariant="normal">Ω</mi> </mrow> </semantics></math>, at reference and incremental configuration.</p> Full article ">Figure 2
<p>Schematic overview of a laminate, highlighting the different failures.</p> Full article ">Figure 3
<p>Effect of anisotropic parameter, <math display="inline"><semantics> <mrow> <mi mathvariant="normal">ς</mi> </mrow> </semantics></math>, on the crack pattern for different fiber orientations represented experimentally in 1-direction and numerically by orange arrows relative to the X-axis: (<b>A</b>) at 30°, (<b>B</b>) at 45°, and (<b>C</b>) at 60° (with a deformation scaling factor of 1.0). Additionally, (<b>D</b>) presents the comparison of load-displacement plot for 45° case. All computations were conducted with a length scale of <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>l</mi> </mrow> <mrow> <mi>ϕ</mi> </mrow> </msub> <mo>=</mo> <mn>0.02</mn> </mrow> </semantics></math> mm. (<b>E</b>) illustrates the influence of the length scale <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>l</mi> </mrow> <mrow> <mi>ϕ</mi> </mrow> </msub> </mrow> </semantics></math> with a fixed value of ς = 50 for 45° case. Experimental results from [<a href="#B74-jcs-08-00533" class="html-bibr">74</a>] were reproduced with permission from Elsevier.</p> Full article ">Figure 4
<p>(<b>A</b>) Geometry and (<b>B</b>) FE model with associated boundary conditions for the curing analysis of the Z-shaped part.</p> Full article ">Figure 5
<p>Residual stress upon the demolding step occurs in the primary global directions: (<b>A</b>) X direction, (<b>B</b>) Y direction, and (<b>C</b>) Z direction (with a deformation scaling factor of 1.0).</p> Full article ">Figure 6
<p>Comparison of spring-in measurements between experimental laser scans and CHILE numerical post-processing.</p> Full article ">Figure 7
<p>(<b>A</b>) Geometry and boundary conditions for the Mode I test, (<b>B</b>) evolution of damage along the interface with a scaling factor of 5.0, and (<b>C</b>) comparison of the load-displacement plot between experimental data [<a href="#B87-jcs-08-00533" class="html-bibr">87</a>] and the PF numerical model.</p> Full article ">Figure 8
<p>Comparison of the delamination front under Mode I loading conditions during repeated loading and unloading steps at displacements of (<b>A</b>) 4 mm, (<b>B</b>) 6 mm, (<b>C</b>) 12 mm, and (<b>D</b>) 15 mm. Experimental results from [<a href="#B87-jcs-08-00533" class="html-bibr">87</a>] were reproduced with permission from Elsevier.</p> Full article ">Figure 9
<p>(<b>A</b>) Geometry and boundary conditions for the Mode II test, (<b>B</b>) evolution of damage along the interface with a scaling factor of 5.0, and (<b>C</b>) comparison of the load-displacement plot between experimental data [<a href="#B88-jcs-08-00533" class="html-bibr">88</a>] and the PF numerical model.</p> Full article ">Figure 10
<p>Associated boundary conditions for (<b>A</b>) the curing simulation using the CHILE model and (<b>B</b>) the structural simulation using the PF model, respectively.</p> Full article ">Figure 11
<p>(<b>A</b>) The overall deformation before and after the demolding step in the curing simulation with respect to the affixed CSYS, and (<b>B</b>) the associated residual stress upon demolding in the primary global directions (with a deformation scaling factor of 1.0).</p> Full article ">Figure 12
<p>Comparison of delamination and matrix cracking in 90° plies based on (<b>A</b>) experimental data [<a href="#B30-jcs-08-00533" class="html-bibr">30</a>] and (<b>B</b>) numerical PF simulations. Experimental results from ref. [<a href="#B30-jcs-08-00533" class="html-bibr">30</a>] were reproduced with permission from Elsevier.</p> Full article ">Figure 13
<p>Comparison of failure loads based on experimental data [<a href="#B30-jcs-08-00533" class="html-bibr">30</a>] and numerical PF simulations, with and without manufacturing-induced residual stresses.</p> Full article ">Figure 14
<p>(<b>A</b>) MRCC (indicated by the red line) and various stochastic thermal loading conditions corresponding to three-dwell cure cycles and modified slower cooling rates; and (<b>B</b>) comparison of failure probabilities in 90° plies under different thermal loading conditions, along with the peak load before failure.</p> Full article ">Figure 15
<p>Comparison of delamination and matrix cracking in 90° plies for a thick L-shaped specimen based on (<b>A</b>) experimental data [<a href="#B30-jcs-08-00533" class="html-bibr">30</a>] and (<b>B</b>) numerical PF simulations without residual stress. Experimental results from ref. [<a href="#B30-jcs-08-00533" class="html-bibr">30</a>] were reproduced with permission from Elsevier.</p> Full article ">Figure 16
<p>(<b>A</b>) Voids in 90° plies within the thick specimen (experimental image from ref. [<a href="#B30-jcs-08-00533" class="html-bibr">30</a>] was reproduced with permission from Elsevier), (<b>B</b>) correlation between curing pressure conditions and void ratio [<a href="#B91-jcs-08-00533" class="html-bibr">91</a>], and (<b>C</b>) schematic representation of random voids along with localized residual stress concentration corresponding to 0.5%, 2.5%, and 3.5% void contents, respectively.</p> Full article ">Figure 17
<p>Comparison of the mean load-displacement plots for stochastic voids within the 90° plies, corresponding to 0.5%, 2.5%, and 3.5% void content alongside experimental data [<a href="#B30-jcs-08-00533" class="html-bibr">30</a>], respectively.</p> Full article ">
24 pages, 4046 KiB  
Article
A Unified Shear Deformation Theory for Piezoelectric Beams with Geometric Nonlinearities—Analytical Modelling and Bending Analysis
by Konstantinos I. Ntaflos, Konstantinos G. Beltsios and Evangelos P. Hadjigeorgiou
J. Compos. Sci. 2024, 8(12), 494; https://doi.org/10.3390/jcs8120494 - 26 Nov 2024
Viewed by 709
Abstract
The objective of the present paper is to demonstrate the effects of shear deformation and large deflections on the piezoelectric materials and structures which often serve as substrate layers of multilayer composite sensors and actuators. Based on a displacement-unified high-order shear deformation theory [...] Read more.
The objective of the present paper is to demonstrate the effects of shear deformation and large deflections on the piezoelectric materials and structures which often serve as substrate layers of multilayer composite sensors and actuators. Based on a displacement-unified high-order shear deformation theory and the von Kármán geometric nonlinearity, a general theory (governing equations and associated boundary conditions) for the analysis of piezoelectric beams is developed using Hamilton’s principle. Nonlinear effects due to the coupling between extensional and bending responses in beams with moderately large rotations but small strains are included. A bending problem for a piezoelectric beam is solved analytically, and the obtained results are compared to the results available in the literature. The numerical results show that both shear deformation effects and von Kármán geometric nonlinearity have a stiffening effect and therefore reduce the displacements. The influence of geometric nonlinearity is more prominent in the case of thin beams, while the effects of shear deformation dominate in the case of thick beams. The proposed unified methodology for the analysis of bending problems is independent of the thickness of the piezoelectric beam. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>(<b>a</b>) Piezoelectric beam under transverse load in <math display="inline"><semantics> <mrow> <mi>x</mi> <mo>–</mo> <mi>z</mi> </mrow> </semantics></math> plane, (<b>b</b>) The cross section of the beam in <math display="inline"><semantics> <mrow> <mi>y</mi> <mo>–</mo> <mi>z</mi> </mrow> </semantics></math> plane.</p> Full article ">Figure 2
<p>Shear stress distribution functions of different high-order shear deformation theories.</p> Full article ">Figure 3
<p>Geometry of the piezoelectric beam subjected to uniformly distributed load <math display="inline"><semantics> <mrow> <mi>q</mi> <mfenced> <mi>x</mi> </mfenced> </mrow> </semantics></math> with hinged–hinged boundary conditions.</p> Full article ">Figure 4
<p>Schematic representation of the resolution method presented in this study.</p> Full article ">Figure 5
<p>Comparison of transverse displacement <math display="inline"><semantics> <mi>w</mi> </semantics></math> at <math display="inline"><semantics> <mrow> <mfenced> <mrow> <mi>x</mi> <mo>,</mo> <mo> </mo> <mi>z</mi> <mo>=</mo> <mn>0</mn> </mrow> </mfenced> </mrow> </semantics></math> with linear and nonlinear models for a PVDF beam through the length of the beam for an aspect ratio S = 2.</p> Full article ">Figure 6
<p>Comparison of transverse displacement <math display="inline"><semantics> <mi>w</mi> </semantics></math> at <math display="inline"><semantics> <mrow> <mfenced> <mrow> <mi>x</mi> <mo>,</mo> <mo> </mo> <mi>z</mi> <mo>=</mo> <mn>0</mn> </mrow> </mfenced> </mrow> </semantics></math> with linear and nonlinear models for a PVDF beam through the length of the beam for an aspect ratio S = 10.</p> Full article ">Figure 7
<p>Comparison of transverse displacement <math display="inline"><semantics> <mi>w</mi> </semantics></math> at <math display="inline"><semantics> <mrow> <mfenced> <mrow> <mi>x</mi> <mo>,</mo> <mo> </mo> <mi>z</mi> <mo>=</mo> <mn>0</mn> </mrow> </mfenced> </mrow> </semantics></math> with linear and nonlinear models for a PVDF beam through the length of the beam for an aspect ratio S = 50.</p> Full article ">Figure 8
<p>Comparison of electric potential <math display="inline"><semantics> <mi>ϕ</mi> </semantics></math> with linear and nonlinear models for a PVDF beam through the length of the beam at <math display="inline"><semantics> <mrow> <mfenced> <mrow> <mi>x</mi> <mo>,</mo> <mo> </mo> <mi>z</mi> <mo>=</mo> <mn>0</mn> </mrow> </mfenced> </mrow> </semantics></math> for an aspect ratio S = 2.</p> Full article ">Figure 9
<p>Comparison of electric potential <math display="inline"><semantics> <mi>ϕ</mi> </semantics></math> with linear and nonlinear models for a PVDF beam through the length of the beam at <math display="inline"><semantics> <mrow> <mfenced> <mrow> <mi>x</mi> <mo>,</mo> <mo> </mo> <mi>z</mi> <mo>=</mo> <mn>0</mn> </mrow> </mfenced> </mrow> </semantics></math> for an aspect ratio S = 10.</p> Full article ">Figure 10
<p>Comparison of electric potential <math display="inline"><semantics> <mi>ϕ</mi> </semantics></math> with linear and nonlinear models for a PVDF beam through the length of the beam at <math display="inline"><semantics> <mrow> <mfenced> <mrow> <mi>x</mi> <mo>,</mo> <mo> </mo> <mi>z</mi> <mo>=</mo> <mn>0</mn> </mrow> </mfenced> </mrow> </semantics></math> for an aspect ratio S = 50.</p> Full article ">
13 pages, 7087 KiB  
Article
Numerical Analysis on Static Performances of Graphene Platelet-Reinforced Ethylene-Tetrafluoroethylene (ETFE) Composite Membrane Under Wind Loading
by Yu Wang, Jiajun Gu, Xin Zhang, Jian Fan, Wenbin Ji and Chuang Feng
J. Compos. Sci. 2024, 8(11), 478; https://doi.org/10.3390/jcs8110478 - 18 Nov 2024
Viewed by 563
Abstract
This study examines the static performances of a graphene platelet (GPL)-reinforced ethylene tetrafluoroethylene (ETFE) composite membrane under wind loadings. The wind pressure distribution on a periodic tensile membrane unit was analyzed by using CFD simulations, which considered various wind velocities and directions. A [...] Read more.
This study examines the static performances of a graphene platelet (GPL)-reinforced ethylene tetrafluoroethylene (ETFE) composite membrane under wind loadings. The wind pressure distribution on a periodic tensile membrane unit was analyzed by using CFD simulations, which considered various wind velocities and directions. A one-way fluid–structure interaction (FSI) analysis incorporating geometric nonlinearity was performed in ANSYS to evaluate the static performances of the composite membrane. The novelty of this research lies in the integration of graphene platelets (GPLs) into ETFE membranes to enhance their static performance under wind loading and the combination of micromechanical modelling for obtaining material properties of the composites and finite element simulation for examining structural behaviors, which is not commonly explored in the existing literature. The elastic properties required for the structural analysis were determined using effective medium theory (EMT), while Poisson’s ratio and mass density were evaluated using rule of mixtures. Parametric studies were carried out to explore the effects of a number of influencing factors, including pre-strain, attributes of wind, and GPL reinforcement. It is demonstrated that higher initial strain effectively reduced deformation under wind loads at the cost of increased stress level. The deformation and stress significantly increased with the increase in wind velocity. The deflection and stress level vary with the wind direction, and the maximum values were observed when the wind comes at 15° and 45°, respectively. Introducing GPLs with a larger surface area into membrane material has proven to be an effective way to control membrane deformation, though it also results in a higher stress level, indicating a trade-off between deformation management and stress management. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>(<b>a</b>) GPL/ETFE composite membrane unit; (<b>b</b>) multiview orthographic projection.</p> Full article ">Figure 2
<p>Building surrounded by periodic GPL/ETFE composite tensile membrane units.</p> Full article ">Figure 3
<p>GPL/ETFE composite membrane with boundary conditions for numerical wind tunnel simulation.</p> Full article ">Figure 4
<p>Boundary conditions of the structural analysis.</p> Full article ">Figure 5
<p>Effects of pre-stretching on maximum deflection and von Mises stress of membrane surface.</p> Full article ">Figure 6
<p>Deformation of ETFE composite membrane unit with different initial strains under 10 m/s wind: (<b>a</b>) initial strain = 0.1%; (<b>b</b>) initial strain = 1.0%.</p> Full article ">Figure 7
<p>Distribution of von Mises stress of ETFE composite membrane with different initial strains under 10 m/s wind: (<b>a</b>) initial strain = 0.1%; (<b>b</b>) initial strain = 1.0%.</p> Full article ">Figure 8
<p>Effect of wind velocity on: (<b>a</b>) maximum deflection and von Mises stress; (<b>b</b>) area-weighted average static pressure on windward size and leeward side of ETFE composite membrane.</p> Full article ">Figure 9
<p>Static pressure distribution on the windward and leeward sides of ETFE tensile membrane subjected to 15 m/s wind with different directions: (<b>a</b>) <math display="inline"><semantics> <mrow> <mi>θ</mi> <mo>=</mo> <mn>0</mn> <mo>°</mo> </mrow> </semantics></math> ; (<b>b</b>) <math display="inline"><semantics> <mrow> <mi>θ</mi> <mo>=</mo> <mn>15</mn> <mo>°</mo> </mrow> </semantics></math>; (<b>c</b>) <math display="inline"><semantics> <mrow> <mi>θ</mi> <mo>=</mo> <mn>30</mn> <mo>°</mo> </mrow> </semantics></math>; (<b>d</b>) <math display="inline"><semantics> <mrow> <mi>θ</mi> <mo>=</mo> <mn>45</mn> <mo>°</mo> </mrow> </semantics></math>; (<b>e</b>) <math display="inline"><semantics> <mrow> <mi>θ</mi> <mo>=</mo> <mn>60</mn> <mo>°</mo> </mrow> </semantics></math>; (<b>f</b>) <math display="inline"><semantics> <mrow> <mi>θ</mi> <mo>=</mo> <mn>75</mn> <mo>°</mo> </mrow> </semantics></math>; (<b>g</b>) <math display="inline"><semantics> <mrow> <mi>θ</mi> <mo>=</mo> <mn>90</mn> <mo>°</mo> </mrow> </semantics></math>.</p> Full article ">Figure 10
<p>Effects of GPL concentration on (<b>a</b>) Young’s modulus and the maximum deflection; (<b>b</b>) von Mises stress, and von Mises strain on GPL/ETFE composite membrane.</p> Full article ">Figure 11
<p>Effect of GPL aspect ratio on (<b>a</b>) Young’s modulus and the maximum deflection; (<b>b</b>) Young’s modulus, and von Mises strain of GPL/ETFE composite membrane subjected to 35 m/s wind.</p> Full article ">
15 pages, 1393 KiB  
Article
The Impact of Activated Carbon–MexOy (Me = Bi, Mo, Zn) Additives on the Thermal Decomposition Kinetics of the Ammonium Nitrate–Magnesium–Nitrocellulose Composite
by Zhanerke Yelemessova, Ayan Yerken, Dana Zhaxlykova and Bagdatgul Milikhat
J. Compos. Sci. 2024, 8(10), 420; https://doi.org/10.3390/jcs8100420 - 12 Oct 2024
Viewed by 1085
Abstract
This research investigates the impact of additives such as activated carbon (AC) combined with metal oxides (Bi2O3, MoO3, and ZnO) on the thermal decomposition kinetics of ammonium nitrate (AN), magnesium (Mg), and nitrocellulose (NC) as a basic [...] Read more.
This research investigates the impact of additives such as activated carbon (AC) combined with metal oxides (Bi2O3, MoO3, and ZnO) on the thermal decomposition kinetics of ammonium nitrate (AN), magnesium (Mg), and nitrocellulose (NC) as a basic AN–Mg–NC composite. To study the thermal properties of the AN–Mg–NC composite with and without the AC–MexOy (Me = Bi, Mo, Zn) additive, a differential scanning calorimetry (DSC) analysis was conducted. The DSC results show that the AC–MexOy (Me = Bi, Mo, Zn) additive catalytically affects the basic AN–Mg–NC composite, lowering the peak decomposition temperature (Tmax) from 534.58 K (AN–Mg–NC) to 490.15 K (with the addition of AC), 490.76 K (with AC–Bi2O3), 492.17 K (with AC–MoO3), and 492.38 K (with AC–ZnO) at a heating rate of β equal to 5 K/min. Based on the DSC data, the activation energies (Ea) for the AN–Mg–NC, AN–Mg–NC–AC, and AN–Mg–NC–AC–MexOy (Me = Bi, Mo, Zn) composites were determined using the Kissinger method. The results suggest that incorporating AC and AC–MexOy (Me = Bi, Mo, Zn) additives reduce the decomposition temperatures and activation energies of the basic AN–Mg–NC composite. Specifically, Ea decreased from 99.02 kJ/mol (for AN–Mg–NC) to 93.63 kJ/mol (with addition of AC), 91.45 kJ/mol (with AC–Bi2O3), 91.65 kJ/mol (with AC–MoO3), and 91.76 kJ/mol (with AC–ZnO). These findings underscore the potential of using AC–MexOy (Me = Bi, Mo, Zn) as a catalytic additive to enhance the performance of AN–Mg–NC-based energetic materials, increasing their efficiency and reliability for use in solid propellants. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>DSC curve of an AN–Mg–NC basic composite heated at <span class="html-italic">β</span> = 5 K/min.</p> Full article ">Figure 2
<p>DSC curves of (<b>a</b>) AN–Mg–NC–AC; (<b>b</b>) AN–Mg–NC–AC–Bi<sub>2</sub>O<sub>3</sub>; (<b>c</b>) AN–Mg–NC–AC–MoO<sub>3</sub>; (<b>d</b>) AN–Mg–NC–AC–ZnO composites heated at <span class="html-italic">β</span> = 5 K/min.</p> Full article ">Figure 3
<p>Kissinger plot of the basic AN–Mg–NC composite.</p> Full article ">Figure 4
<p>Kissinger plot of the AN–Mg–NC–AC composite.</p> Full article ">Figure 5
<p>Kissinger plot of the AN–Mg–NC–AC–Bi<sub>2</sub>O<sub>3</sub> composite.</p> Full article ">Figure 6
<p>Kissinger plot of the AN–Mg–NC–AC–MoO<sub>3</sub> composite.</p> Full article ">Figure 7
<p>Kissinger plot of the AN–Mg–NC–AC–ZnO composite.</p> Full article ">
22 pages, 5451 KiB  
Article
Synthesis of a New Composite Material Derived from Cherry Stones and Sodium Alginate—Application to the Adsorption of Methylene Blue from Aqueous Solution: Process Parameter Optimization, Kinetic Study, Equilibrium Isotherms, and Reusability
by Cristina-Gabriela Grigoraș and Andrei-Ionuț Simion
J. Compos. Sci. 2024, 8(10), 402; https://doi.org/10.3390/jcs8100402 - 3 Oct 2024
Viewed by 983
Abstract
Purifying polluted water is becoming a crucial concern to meet quantity and quality demands as well as to ensure the resource’s sustainability. In this study, a new material was prepared from cherry stone powder and sodium alginate, and its capacity to remove methylene [...] Read more.
Purifying polluted water is becoming a crucial concern to meet quantity and quality demands as well as to ensure the resource’s sustainability. In this study, a new material was prepared from cherry stone powder and sodium alginate, and its capacity to remove methylene blue (MB) from water was determined. The characterization of the resulting product, performed via scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR), revealed that the raw material considered for the synthesis was successfully embedded in the polymeric matrix. The impact of three of the main working parameters (pH 3–9, adsorbent dose 50–150 g/L, contact time 60–180 min) on the retention of MB was evaluated through response surface methodology with a Box–Behnken design. In the optimal settings, a removal efficiency of 80.46% and a maximum sorption capacity of 0.3552 mg/g were recorded. MB retention followed the pseudo-second-order kinetic and was suitably described by Freundlich, Khan, Redlich–Peterson, and Sips isotherm models. The experimental results show that the synthesized composite can be used for at least three successive cycles of MB adsorption. From these findings, it can be concluded that the use of the cherry-stone-based adsorbent is environmentally friendly, and efficacious in the removal of contaminants from the water environment. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Preparation of CSSA.</p> Full article ">Figure 2
<p>SEM micrographs of CSSA before (<b>A</b>) and after (<b>B</b>) MB adsorption.</p> Full article ">Figure 3
<p>FTIR spectra for CSSA before (<b>A</b>), and after (<b>B</b>) MB adsorption.</p> Full article ">Figure 4
<p><span class="html-italic">p</span>H<sub>PZC</sub> of the CSSA.</p> Full article ">Figure 5
<p>RSM-BBD plots for predicted vs. actual values of MB final concentration (<b>A</b>), and for perturbation of all decision variables (<b>B</b>).</p> Full article ">Figure 6
<p>The 3D response surfaces and 2D contour plots of interaction occurring between CSSA dose and <span class="html-italic">p</span>H (<b>A</b>), time and <span class="html-italic">p</span>H (<b>B</b>), and time and CSSA dose (<b>C</b>).</p> Full article ">Figure 7
<p>Optimized working conditions and corresponding value of the response function.</p> Full article ">Figure 8
<p>Kinetic of MB adsorption on the prepared composite at different dye concentrations ((<b>A</b>) 10 mg/L, (<b>B</b>) 20 mg/L, (<b>C</b>) 30 mg/L, (<b>D</b>) 40 mg/L, (<b>E</b>) 50 mg/L).</p> Full article ">Figure 9
<p>Kinetic models for the adsorption on CSSA at different MB concentrations ((<b>A</b>) 10 mg/L, (<b>B</b>) 20 mg/L, (<b>C</b>) 30 mg/L, (<b>D</b>) 40 mg/L, (<b>E</b>) 50 mg/L).</p> Full article ">Figure 10
<p>Equilibrium isotherms for MB adsorption on CSSA.</p> Full article ">Figure 11
<p>Adsorption–desorption cycles for MB–CSSA system.</p> Full article ">
13 pages, 2347 KiB  
Article
Nitrogen-Doped Borophene Quantum Dots: A Novel Sensing Material for the Detection of Hazardous Environmental Gases
by Kriengkri Timsorn and Chatchawal Wongchoosuk
J. Compos. Sci. 2024, 8(10), 397; https://doi.org/10.3390/jcs8100397 - 1 Oct 2024
Cited by 2 | Viewed by 1658
Abstract
Toxic gases emitted by industries and vehicles cause environmental pollution and pose significant health risks which are becoming increasingly dangerous. Therefore, the detection of the toxic gases is crucial. The development of gas sensors with high sensitivity and fast response based on nanomaterials [...] Read more.
Toxic gases emitted by industries and vehicles cause environmental pollution and pose significant health risks which are becoming increasingly dangerous. Therefore, the detection of the toxic gases is crucial. The development of gas sensors with high sensitivity and fast response based on nanomaterials has garnered significant interest. In this work, we studied the adsorption behavior of B9− wheel structures of pristine and nitrogen functionalized borophene quantum dots for major hazardous environmental gases, such as NO2, CO2, CO, and NH3. The self-consistent-charge density-functional tight-binding method (SCC-DFTB) method was performed to investigate structural geometries, the most favorable adsorption sites, charge transfer, total densities of states, and electronic properties of the structures before and after adsorption of the gas molecules. Based on calculated results, it was found that the interaction between the borophene quantum dots and the gas molecules was chemisorption. The functionalized nitrogen atom contributed to impurity states, leading to higher adsorption energies of the functionalized borophene quantum dots compared to the pristine ones. Total densities of states revealed insights into electronic properties of gas molecules adsorbed on borophene quantum dots. The nitrogen-doped borophene quantum dots demonstrated excellent performance as a sensing material for hazardous environmental gases, especially CO2. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>(<b>a</b>) Side and top views of the optimized structures of <math display="inline"><semantics> <msup> <mrow> <msub> <mi mathvariant="normal">B</mi> <mn>9</mn> </msub> </mrow> <mo>−</mo> </msup> </semantics></math> and <math display="inline"><semantics> <mrow> <mi mathvariant="normal">N</mi> <mo>/</mo> <msup> <mrow> <msub> <mi mathvariant="normal">B</mi> <mn>9</mn> </msub> </mrow> <mo>−</mo> </msup> </mrow> </semantics></math> BQDs and (<b>b</b>) DOS of the structures.</p> Full article ">Figure 2
<p>Side and top views of some optimized <math display="inline"><semantics> <msup> <mrow> <msub> <mi mathvariant="normal">B</mi> <mn>9</mn> </msub> </mrow> <mo>−</mo> </msup> </semantics></math> BQDs for adsorption of (<b>a</b>) NO<sub>2</sub>, (<b>b</b>) CO<sub>2</sub>, (<b>c</b>) CO, and (<b>d</b>) NH<sub>3</sub> with perpendicular and parallel orientations.</p> Full article ">Figure 3
<p>Side and top views of some optimized <math display="inline"><semantics> <mrow> <mi>N</mi> <mo>/</mo> <msup> <mrow> <msub> <mi mathvariant="normal">B</mi> <mn>9</mn> </msub> </mrow> <mo>−</mo> </msup> </mrow> </semantics></math> BQDs for adsorption of (<b>a</b>) NO<sub>2</sub>, (<b>b</b>) CO<sub>2</sub>, (<b>c</b>) CO, and (<b>d</b>) NH<sub>3</sub> with perpendicular and parallel orientations.</p> Full article ">Figure 4
<p>Calculated DOSs for (<b>a</b>) NO<sub>2</sub>, (<b>b</b>) CO, (<b>c</b>) CO<sub>2</sub>, and (<b>d</b>) NH<sub>3</sub> adsorbed on <math display="inline"><semantics> <msup> <mrow> <msub> <mi mathvariant="normal">B</mi> <mn>9</mn> </msub> </mrow> <mo>−</mo> </msup> </semantics></math> and <math display="inline"><semantics> <mrow> <mi mathvariant="normal">N</mi> <mo>/</mo> <msup> <mrow> <msub> <mi mathvariant="normal">B</mi> <mn>9</mn> </msub> </mrow> <mo>−</mo> </msup> </mrow> </semantics></math> BQDs structures. The Fermi level is set to zero with dashed vertical lines.</p> Full article ">
18 pages, 1565 KiB  
Article
Design of an Overhead Crane in Steel, Aluminium and Composite Material Using the Prestress Method
by Luigi Solazzi and Ivan Tomasi
J. Compos. Sci. 2024, 8(9), 380; https://doi.org/10.3390/jcs8090380 - 23 Sep 2024
Viewed by 1220
Abstract
The present research describes a design of an overhead crane using different materials with a prestress method, which corresponds to an external compression force with the aim of reducing the displacement of the beam due to the external load. This study concerns a [...] Read more.
The present research describes a design of an overhead crane using different materials with a prestress method, which corresponds to an external compression force with the aim of reducing the displacement of the beam due to the external load. This study concerns a bridge crane with a span length of 10 m, with a payload equal to 20,000 N and an estimated fatigue life of 50,000 cycles. Three different materials are studied: steel S355JR, aluminium alloy 6061-T6 and carbon fibre-reinforced polymer (CFRP). These materials are analysed with and without the contribution of the prestress method. In reference to the prestressed steel solution (which has a weight equal to 79% of the non-prestressed configuration), this study designed an aluminium solution that is 50.7% of the weight of the steel one and a composite solution that is always 20.3% of the steel configuration. In combining the methods, i.e., the materials and prestress, compared to the non-prestressed steel solution with a weight evaluated to be 758 kg, the weight of the aluminium configuration is equal to 40% of the traditional one, and the composite value is reduced to 16%, with a weight of 121 kg. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>Dimensions of the analyzed overhead crane, with zoomed-in views of the constraints; the permitted movements and rotations are indicated by arrows.</p> Full article ">Figure 2
<p>Schematisation of the crane boom and section adopted. (<b>a</b>) Schematisation of the boom analysed. (<b>b</b>) Sections adopted of the configurations. (<b>c</b>) Position of the precompression force respect to the beam.</p> Full article ">Figure 3
<p>Coordinate system for the position of laminas.</p> Full article ">Figure 4
<p>Model adopted for the CFRP solution with a zoomed view to represent the mesh used. To simplify the simulation, the fillets at the corners of the cross-section have been neglected, but this modification does not affect the results due to the small size of these dimensions compared to the overall structure.</p> Full article ">Figure 5
<p>Total displacement of the main boom in CFRP: the top shows the displacement without payload, while the bottom shows the displacement with payload.</p> Full article ">Figure 6
<p>Buckling mode of the analysed configurations. (<b>a</b>) First buckling mode of the HEA beam <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>η</mi> <mrow> <mi>s</mi> <mi>t</mi> <mi>e</mi> <mi>e</mi> <mi>l</mi> </mrow> </msub> <mo>=</mo> <mn>14.03</mn> <mspace width="0.166667em"/> <mspace width="0.166667em"/> <mspace width="0.166667em"/> <mspace width="0.166667em"/> <msub> <mi>η</mi> <mrow> <mi>A</mi> <mi>l</mi> </mrow> </msub> <mo>=</mo> <mn>7.33</mn> <mo>)</mo> </mrow> </semantics></math>. (<b>b</b>) Second buckling mode of the HEA beam <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>η</mi> <mrow> <mi>s</mi> <mi>t</mi> <mi>e</mi> <mi>e</mi> <mi>l</mi> </mrow> </msub> <mo>=</mo> <mn>15.84</mn> <mspace width="0.166667em"/> <mspace width="0.166667em"/> <mspace width="0.166667em"/> <mspace width="0.166667em"/> <msub> <mi>η</mi> <mrow> <mi>A</mi> <mi>l</mi> </mrow> </msub> <mo>=</mo> <mn>11.92</mn> <mo>)</mo> </mrow> </semantics></math>. (<b>c</b>) First buckling mode of the CFRP beam <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>η</mi> <mrow> <mi>C</mi> <mi>F</mi> <mi>R</mi> <mi>P</mi> </mrow> </msub> <mo>=</mo> <mn>10.07</mn> <mo>)</mo> </mrow> </semantics></math>. (<b>d</b>) Second buckling mode of the CFRP beam <math display="inline"><semantics> <mrow> <mo>(</mo> <msub> <mi>η</mi> <mrow> <mi>C</mi> <mi>F</mi> <mi>R</mi> <mi>P</mi> </mrow> </msub> <mo>=</mo> <mn>10.1</mn> <mo>)</mo> </mrow> </semantics></math>.</p> Full article ">Figure 7
<p>Modal analysis of the prestressed configurations.(<b>a</b>) First vibration mode of the S355JR beam (<math display="inline"><semantics> <msub> <mi>ω</mi> <mrow> <mi>s</mi> <mi>t</mi> <mi>e</mi> <mi>e</mi> <mi>l</mi> </mrow> </msub> </semantics></math> = 7.87 Hz). (<b>b</b>) Second vibration mode of the S355JR beam (<math display="inline"><semantics> <msub> <mi>ω</mi> <mrow> <mi>s</mi> <mi>t</mi> <mi>e</mi> <mi>e</mi> <mi>l</mi> </mrow> </msub> </semantics></math> = 10.66 Hz). (<b>c</b>) First vibration mode of the Al 6061-T6 beam (<math display="inline"><semantics> <msub> <mi>ω</mi> <mrow> <mi>A</mi> <mi>l</mi> </mrow> </msub> </semantics></math> = 9.57 Hz). (<b>d</b>) Second vibration mode of the Al 6061-T6 beam (<math display="inline"><semantics> <msub> <mi>ω</mi> <mrow> <mi>A</mi> <mi>l</mi> </mrow> </msub> </semantics></math> = 10.32 Hz). (<b>e</b>) First vibration mode of the CFRP beam (<math display="inline"><semantics> <msub> <mi>ω</mi> <mrow> <mi>C</mi> <mi>F</mi> <mi>R</mi> <mi>P</mi> </mrow> </msub> </semantics></math> = 14.92 Hz). (<b>f</b>) Second vibration mode of the CFRP beam (<math display="inline"><semantics> <msub> <mi>ω</mi> <mrow> <mi>C</mi> <mi>F</mi> <mi>R</mi> <mi>P</mi> </mrow> </msub> </semantics></math> = 18.76 Hz).</p> Full article ">Figure 8
<p>3D model of the overhead crane designed in CFRP.</p> Full article ">Figure 9
<p>Main areas designed for the new innovative solution. (<b>a</b>) Zoom of the trolley on the bridge. (<b>b</b>) Detail of the hinge side of the runway system. (<b>c</b>) Second view of the runway system. (<b>d</b>) View of the roller side of the runway system.</p> Full article ">Figure 10
<p>Column chart showing the percentage weight of each solution compared to the non-prestressed steel configuration.</p> Full article ">
17 pages, 4548 KiB  
Article
Fracture Behavior of Crack-Damaged Concrete Beams Reinforced with Ultra-High-Performance Concrete Layers
by Zenghui Guo, Xuejun Tao, Zhengwei Xiao, Hui Chen, Xixi Li and Jianlin Luo
J. Compos. Sci. 2024, 8(9), 355; https://doi.org/10.3390/jcs8090355 - 10 Sep 2024
Viewed by 1476
Abstract
Reinforcing crack-damaged concrete structures with ultra-high-performance concrete (UHPC) proves to be more time-, labor-, and cost-efficient than demolishing and rebuilding under the dual-carbon strategy. In this study, the extended finite element method (XFEM) in ABAQUS was first employed to develop a numerical model [...] Read more.
Reinforcing crack-damaged concrete structures with ultra-high-performance concrete (UHPC) proves to be more time-, labor-, and cost-efficient than demolishing and rebuilding under the dual-carbon strategy. In this study, the extended finite element method (XFEM) in ABAQUS was first employed to develop a numerical model of UHPC-reinforced single-notched concrete (U+SNC) beams, analyze their crack extension behavior, and obtain the parameters necessary for calculating fracture toughness. Subsequently, the fracture toughness and instability toughness of U+SNC were calculated using the improved double K fracture criterion. The effects of varying crack height ratios (a/h) of SNC, layer thicknesses (d) of UHPC reinforcement, and fiber contents in UHPC (VSF) on the fracture properties of U+SNC beams were comprehensively investigated. The results indicate that (1) the UHPC reinforcement layer significantly enhances the load-carrying capacity and crack resistance of the U+SNC beams. Crack extension in the reinforced beams occurs more slowly than in the unreinforced beams; |(2) the fracture performance of the U+BNC beams increases exponentially with d. Considering both the reinforcement effect benefit and beam deadweight, the optimal cost-effective performance is achieved when d is 20 mm; (3) with constant d, increasing a/h favors the reinforcement effect of UHPC on the beams; (4) as VSF increases, the crack extension stage in the U+BNC beam becomes more gradual, with higher toughness and flexural properties; therefore, the best mechanical properties are achieved at a VSF of 3%. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>Geometric modeling of RC in Ref. [<a href="#B47-jcs-08-00355" class="html-bibr">47</a>] (The dotted line represents the longitudinal rebar).</p> Full article ">Figure 2
<p>Comparison of RC crack propagation state with that in Ref. [<a href="#B47-jcs-08-00355" class="html-bibr">47</a>].</p> Full article ">Figure 3
<p>The calculated results of this study compared with the experimental results in Ref. [<a href="#B47-jcs-08-00355" class="html-bibr">47</a>].</p> Full article ">Figure 4
<p>Geometric model of U+SNC three-point bending beam (unit: mm).</p> Full article ">Figure 5
<p>Traction–separation curve of U+SNC.</p> Full article ">Figure 6
<p>XFEM model of U+SNC beam with 0.4 <span class="html-italic">a/h</span>.</p> Full article ">Figure 7
<p>Roadmap of U+SNC fracture toughness calculation.</p> Full article ">Figure 8
<p>Three-stage stress nephograms of U+SNC beam with 20 mm <span class="html-italic">d</span> and 0.4 <span class="html-italic">a/h</span>: (<b>a</b>) U+SNC begins to crack; (<b>b</b>) UHPC layer completely ruptures; (<b>c</b>) U+SNC completely ruptures.</p> Full article ">Figure 9
<p><span class="html-italic">F</span>-<span class="html-italic">CMOD</span> curves and fracture toughness of U+SNC beams with different <span class="html-italic">ds</span> and 0.4 <span class="html-italic">a/h</span>: (<b>a</b>) <span class="html-italic">F-CMOD</span> curves; (<b>b</b>) fracture toughness.</p> Full article ">Figure 10
<p><span class="html-italic">F-CMOD</span> curves and fracture toughness of U+SNC with different <span class="html-italic">a/h</span> ratios and 20 mm <span class="html-italic">d</span>: (<b>a</b>) F-CMOD curves; (<b>b</b>) fracture toughness.</p> Full article ">Figure 11
<p><span class="html-italic">F-CMOD</span> curves and fracture toughness of U+SNC with different SF contents, 20 mm <span class="html-italic">d</span>, and 0.4 <span class="html-italic">a/h</span>: (<b>a</b>) F-CMOD curves; (<b>b</b>) fracture toughness.</p> Full article ">
13 pages, 3582 KiB  
Article
Shear Behavior and Modeling of Short Glass Fiber- and Talc-Filled Recycled Polypropylene Composites at Different Operating Temperatures
by Andrea Iadarola, Pietro Di Matteo, Raffaele Ciardiello, Francesco Gazza, Vito Guido Lambertini, Valentina Brunella and Davide Salvatore Paolino
J. Compos. Sci. 2024, 8(9), 345; https://doi.org/10.3390/jcs8090345 - 3 Sep 2024
Viewed by 1157
Abstract
The present paper aims to broaden the field of application of the phenomenological model proposed by the authors in a previous study (ICP model) and to assess the shear properties of a recycled 30 wt.% talc-filled polypropylene (TFPP) and a recycled 30 wt.% [...] Read more.
The present paper aims to broaden the field of application of the phenomenological model proposed by the authors in a previous study (ICP model) and to assess the shear properties of a recycled 30 wt.% talc-filled polypropylene (TFPP) and a recycled 30 wt.% short glass fiber-reinforced polypropylene (SGFPP), used in the automotive industry. The materials were produced by injection molding employing post-industrial mechanical shredding of recycled materials. In particular, Iosipescu shear tests adopting the American Standard for Testing Materials (ASTM D5379) at three different operating temperatures (−40, 23 and 85 °C) were performed. The strain was acquired using a Digital Image Correlation (DIC) system to determine the map of the strain in the area of interest before failure. Lower operating temperatures led to higher shear chord moduli and higher strengths. Recycled SGFPP material showed higher mechanical properties and smaller strains at failure with respect to recycled TFPP. Finally, the ICP model also proved to be suitable and accurate for the prediction of the shear behavior of 30 wt.% SGFPP and 30 wt.% TFPP across different operating temperatures. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>Schematic representation of the dies and the geometry of the injection gate and the resulting composite plate [<a href="#B28-jcs-08-00345" class="html-bibr">28</a>].</p> Full article ">Figure 2
<p>Representation of (<b>a</b>) the V-Notched Beam Test Fixture and (<b>b</b>) a magnification of the notched area of the specimen mounted in the testing fixture during testing.</p> Full article ">Figure 3
<p>Shear stress–strain curves and predicted results for tensile behavior of PP65.40 at (<b>a</b>) −40 °C; (<b>b</b>) 23 °C; and (<b>c</b>) 85 °C.</p> Full article ">Figure 4
<p>Shear stress–strain curves and predicted results for tensile behavior of PP140.80 at (<b>a</b>) −40 °C; (<b>b</b>) 23 °C; and (<b>c</b>) 85 °C.</p> Full article ">Figure 5
<p>Shear stress–strain curves and optimized predicted results for tensile behavior of PP140.80 at (<b>a</b>) 23 °C, adopting an 8th-degree polynomial and (<b>b</b>) 85 °C, adopting a 9th-degree polynomial.</p> Full article ">
12 pages, 3722 KiB  
Article
Mechanical and Physical Characteristics of Oil Palm Empty Fruit Bunch as Fine Aggregate Replacement in Ordinary Portland Cement Mortar Composites
by Sotya Astutiningsih, Rahmat Zakiy Ashma’, Hammam Harits Syihabuddin, Evawani Ellisa and Muhammad Saukani
J. Compos. Sci. 2024, 8(9), 341; https://doi.org/10.3390/jcs8090341 - 30 Aug 2024
Viewed by 901
Abstract
Palm oil empty fruit bunch (OEB) is the largest source of waste in the production of crude palm oil. Utilizing this waste in various applications can help reduce its volume and mitigate adverse environmental effects. In this study, fibers from OEB without any [...] Read more.
Palm oil empty fruit bunch (OEB) is the largest source of waste in the production of crude palm oil. Utilizing this waste in various applications can help reduce its volume and mitigate adverse environmental effects. In this study, fibers from OEB without any chemical treatment are introduced into Ordinary Portland Cement (OPC)-based mortar to partially replace fine aggregates, aiming to reduce the mortar’s density. The goal of this experimental study is to observe the mechanical and physical performance of the samples according to the effect of the addition of OEB. The composite samples were made by replacing 1%, 2%, and 3% of the weight of quartz sand as the fine aggregate with OEB (fine and coarse). The hardened composites were further tested to determine their compressive strength, and it was found that the replacement of sand with OEB led to a decrease in compressive strength and flowability while alleviating the mortar’s density and affecting the setting time. The decrease in compressive strength was attributed to cavities present in the samples. Flexural tests and 28-day drying shrinkage measurements were carried out on the samples with 1% replacement of sand with OEB. The experiments showed that OEB fibers increased the flexural strength, functioned as a crack barrier, and reduced drying shrinkage. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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Graphical abstract

Graphical abstract
Full article ">Figure 1
<p>Optical microscope images of fine OEB (<b>a</b>), coarse OEB (<b>b</b>), and quartz sand (<b>c</b>).</p> Full article ">Figure 2
<p>Effect of OEB aggregate on mortar samples, (<b>a</b>) flowability, and (<b>b</b>) setting time.</p> Full article ">Figure 3
<p>(<b>a</b>) Compressive strength characterization of mortar samples, (<b>b</b>) Photographs of COEB mortar fracture surface.</p> Full article ">Figure 4
<p>The photographs of mortar samples in different surface positions: (<b>a</b>) the free surface of FOEB1, (<b>b</b>) the free surface of COEB1, (<b>c</b>) the bottom surface of FOEB1, (<b>d</b>) the bottom surface of COEB1, (<b>e</b>) the sidewall surface of FOEB1, and (<b>f</b>) the sidewall surface of COEB1.</p> Full article ">Figure 5
<p>Photographs of COEB1 samples after compression test, each taken from 3 different angles.</p> Full article ">Figure 6
<p>The crack pattern of flexural test specimens: (<b>a</b>) control sample and (<b>b</b>) COEB1 sample. (<b>c</b>) Photographs of the sidewall surface COEB1 samples after flexural test action. (<b>d</b>) The flexural strength between the control and COEB1 samples.</p> Full article ">Figure 7
<p>Drying shrinkage of the control and COEB1 samples (<b>a</b>) for the first 24 h and (<b>b</b>) daily shrinkage for 28 days.</p> Full article ">
23 pages, 7759 KiB  
Article
Machine Learning Algorithms for Prediction and Characterization of Cohesive Zone Parameters for Mixed-Mode Fracture
by Arash Ramian and Rani Elhajjar
J. Compos. Sci. 2024, 8(8), 326; https://doi.org/10.3390/jcs8080326 - 17 Aug 2024
Viewed by 1255
Abstract
Fatigue and fracture prediction in composite materials using cohesive zone models depends on accurately characterizing the core and facesheet interface in advanced composite sandwich structures. This study investigates the use of machine learning algorithms to identify cohesive zone parameters used in the fracture [...] Read more.
Fatigue and fracture prediction in composite materials using cohesive zone models depends on accurately characterizing the core and facesheet interface in advanced composite sandwich structures. This study investigates the use of machine learning algorithms to identify cohesive zone parameters used in the fracture analysis of advanced composite sandwich structures. Experimental results often yield non-unique solutions, complicating the determination of cohesive parameters. Numerical determination can be time-consuming due to fine mesh requirements near the crack tip. This research evaluates the performance of Support Vector Regression (SVR), Random Forest (RF), and Artificial Neural Network (ANN) machine learning methods. The study uses features extracted from load–displacement responses during the fracture of the Asymmetric Double-Cantilever Beam (ADCB) specimen. The inputs include the displacement at the maximum load (δ*), the maximum load (Pmax), the total area under the load–displacement curve (At), and the initial slope of the linear region of the load–displacement curve (m). There are two objectives in this research: the first is to investigate which method performs best in identifying the interfacial cohesive parameters between the honeycomb core and carbon-epoxy facesheets, while the second objective is to reduce the dimensionality of the dataset by reducing the number of input features. Reducing the number of inputs can simplify the models and potentially improve the performance and interpretability. The results show that the ANN method produced the best results, with a mean absolute percentage error (MAPE) of 0.9578% and an R-squared (R²) value of 0.7932. These values indicate a high level of accuracy in predicting the four cohesive zone parameters: maximum normal contact stress (σI), critical fracture energy for normal separation (GI), maximum equivalent tangential contact stress (σII), and critical fracture energy for tangential slip (GII). Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>Schematic of the ADCB specimen for composite sandwich structure and the linear softening cohesive law for mixed-mode I + II fracture process. <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>δ</mi> </mrow> <mrow> <mi>o</mi> <mi>m</mi> </mrow> </msub> </mrow> </semantics></math> = damage onset relative displacement. <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>δ</mi> </mrow> <mrow> <mi>u</mi> <mi>m</mi> </mrow> </msub> </mrow> </semantics></math> = ultimate relative displacement. <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>σ</mi> </mrow> <mrow> <mi>u</mi> <mi>m</mi> </mrow> </msub> </mrow> </semantics></math> = local strength.</p> Full article ">Figure 2
<p>Representation of the linear SVR model showing support vectors and regression line.</p> Full article ">Figure 3
<p>Representation of RF model for determining cohesive zone model parameters.</p> Full article ">Figure 4
<p>Representation of ANN architecture for identifying cohesive zone parameters.</p> Full article ">Figure 5
<p>Validation study showing the load–displacement curve obtained from our finite element (FE) model (blue line) for the sandwich structure using the Asymmetric Double-Cantilever Beam (ADCB) specimen, compared to experimental data (black line) from the literature [<a href="#B62-jcs-08-00326" class="html-bibr">62</a>].</p> Full article ">Figure 6
<p>Load versus displacement curves in the database from ADCB fracture simulations.</p> Full article ">Figure 7
<p>Predicted versus actual outputs of CZM parameters using the Support Vector Regression (SVR) model for the training dataset.</p> Full article ">Figure 8
<p>Predicted versus actual outputs of CZM parameters using the Support Vector Regression (SVR) model for the testing dataset.</p> Full article ">Figure 9
<p>Predicted versus actual outputs of CZM parameters using Random Forest (RF) for the training dataset.</p> Full article ">Figure 10
<p>Predicted versus actual outputs of CZM parameters using the Random Forest (RF) model for the testing dataset.</p> Full article ">Figure 11
<p>Predicted versus actual outputs of CZM parameters using the Artificial Neural Network (ANN) model for the training dataset.</p> Full article ">Figure 12
<p>Predicted versus actual outputs of CZM parameters using the Artificial Neural Network (ANN) model for the testing dataset.</p> Full article ">Figure 13
<p>Comparison of <math display="inline"><semantics> <mrow> <msup> <mrow> <mi>R</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> </mrow> </semantics></math> and MAPE for the ML algorithms relative to the CZM parameters.</p> Full article ">Figure 14
<p>The importance of key parameters from the load–displacement curve from the ADCB test for the machine learning model effectiveness.</p> Full article ">Figure 15
<p>Comparative analysis of load–displacement curve predicted by ML models and FE analysis for composite sandwich structures.</p> Full article ">Figure 16
<p>Comparative assessment of load–displacement curves by different ML techniques and FE modeling for data beyond the training range.</p> Full article ">
17 pages, 3847 KiB  
Article
Molecular Dynamics Simulations of Effects of Geometric Parameters and Temperature on Mechanical Properties of Single-Walled Carbon Nanotubes
by Lida Najmi and Zhong Hu
J. Compos. Sci. 2024, 8(8), 293; https://doi.org/10.3390/jcs8080293 - 30 Jul 2024
Viewed by 1233
Abstract
Carbon nanotubes (CNTs) are considered an advanced form of carbon. They have superior characteristics in terms of mechanical and thermal properties compared to other available fibers and can be used in various applications, such as supercapacitors, sensors, and artificial muscles. The properties of [...] Read more.
Carbon nanotubes (CNTs) are considered an advanced form of carbon. They have superior characteristics in terms of mechanical and thermal properties compared to other available fibers and can be used in various applications, such as supercapacitors, sensors, and artificial muscles. The properties of single-walled carbon nanotubes (SWNTs) are significantly affected by geometric parameters such as chirality and aspect ratio, and testing conditions such as temperature and strain rate. In this study, the effects of geometric parameters and temperature on the mechanical properties of SWNTs were studied by molecular dynamics (MD) simulations using the Large-scaled Atomic/Molecular Massively Parallel Simulator (LAMMPS). Based on the second-generation reactive empirical bond order (REBO) potential, SWNTs of different diameters were tested in tension and compression under different strain rates and temperatures to understand their effects on the mechanical behavior of SWNTs. It was observed that the Young’s modulus and the tensile strength decreases with increasing SWNT tube diameter. As the chiral angle increases, the tensile strength increases, while the Young’s modulus decreases. The simulations were repeated at different temperatures of 300 K, 900 K, 1500 K, 2100 K and different strain rates of 1 × 10−3/ps, 0.75 × 10−3/ps, 0.5 × 10−3/ps, and 0.25 × 10−3/ps to investigate the effects of temperature and strain rate, respectively. The results show that the ultimate tensile strength of SWNTs increases with increasing strain rate. It is also seen that when SWNTs were stretched at higher temperatures, they failed at lower stresses and strains. The compressive behavior results indicate that SWNTs tend to buckle under lower stresses and strains than those under tensile stress. The simulation results were validated by and consistent with previous studies. The presented approach can be applied to investigate the properties of other advanced materials. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>Schematic model and boundary condition setup for tensile or compressive testing.</p> Full article ">Figure 2
<p>Tensile behavior and failure modes of selected SWNTs with a diameter of approximately 0.75 nm. (<b>A</b>): initial SWNT configuration before displacement; (<b>B</b>): SWNT configuration when necking occurs; (<b>C</b>): SWNT configuration after failure.</p> Full article ">Figure 3
<p>The stress–strain behavior of zigzag SWNTs under tensile with a diameter of ~0.75 nm, a nanotube length of 5 nm, and strain rate of 0.001/ps at different temperatures.</p> Full article ">Figure 4
<p>Tensile strength of armchair SWNTs with a nanotube length of 5 nm at different diameters and temperatures.</p> Full article ">Figure 5
<p>Tensile strength of zigzag SWNTs with a nanotube length of 5 nm at different diameters and temperatures.</p> Full article ">Figure 6
<p>Young’s modulus of armchair SWNTs with a nanotube length of 5 nm at different diameters and temperatures.</p> Full article ">Figure 7
<p>Young’s modulus of zigzag SWNTs with a nanotube length of 5 nm at different diameters and temperatures.</p> Full article ">Figure 8
<p>Tensile strength of SWNTs with a tube length of 5 nm and a diameter of 0.75 nm at different chirality and temperatures.</p> Full article ">Figure 9
<p>Young’s modulus of SWNTs with a tube length of 5 nm and a diameter of 0.75 nm at different chirality and temperatures.</p> Full article ">Figure 10
<p>Tensile strength of zigzag SWNTs with a tube length of 5 nm and a diameter of 0.75 nm at different strain rates and temperatures.</p> Full article ">Figure 11
<p>Compressive failure modes of zigzag SWNTs with a diameter of approximately 0.75 nm and a length of 5 nm. (<b>A</b>): initial configuration; (<b>B</b>): configuration when buckling occurs; (<b>C</b>): configuration after failure.</p> Full article ">Figure 12
<p>Compressive stress–strain behavior of z SWNTs with a diameter of 0.75 nm and a nanotube length of 5 nm at different temperatures.</p> Full article ">
10 pages, 3234 KiB  
Article
Ab Initio Modelling of g-ZnO Deposition on the Si (111) Surface
by Aliya Alzhanova, Yuri Mastrikov and Darkhan Yerezhep
J. Compos. Sci. 2024, 8(7), 281; https://doi.org/10.3390/jcs8070281 - 20 Jul 2024
Viewed by 883
Abstract
Recent studies show that zinc oxide (ZnO) nanostructures have promising potential as an absorbing material. In order to improve the optoelectronic properties of the initial system, this paper considers the process of adsorbing multilayer graphene-like ZnO onto a Si (111) surface. The density [...] Read more.
Recent studies show that zinc oxide (ZnO) nanostructures have promising potential as an absorbing material. In order to improve the optoelectronic properties of the initial system, this paper considers the process of adsorbing multilayer graphene-like ZnO onto a Si (111) surface. The density of electron states for two- and three-layer graphene-like zinc oxide on the Si (111) surface was obtained using the Vienna ab-initio simulation package by the DFT method. A computer model of graphene-like Zinc oxide on a Si (111)-surface was created using the DFT+U approach. One-, two- and three-plane-thick graphene-zinc oxide were deposited on the substrate. An isolated cluster of Zn3O3 was also considered. The compatibility of g-ZnO with the S (100) substrate was tested, and the energetics of deposition were calculated. This study demonstrates that, regardless of the possible configuration of the adsorbing layers, the Si/ZnO structure remains stable at the interface. Calculations indicate that, in combination with lower formation energies, wurtzite-type structures turn out to be more stable and, compared to sphalerite-type structures, wurtzite-type structures form longer interlayers and shorter interplanar distances. It has been shown that during the deposition of the third layer, the growth of a wurtzite-type structure becomes exothermic. Thus, these findings suggest a predictable relationship between the application method and the number of layers, implying that the synthesis process can be modified. Consequently, we believe that such interfaces can be obtained through experimental synthesis. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>Graphene-like ZnO monolayer: 6.02 × 6.02 Å surface unit (dotted line), four ZnO formula units. Zn-O distance—1.74 Å. Gray and red balls denote Zn and O, respectively.</p> Full article ">Figure 2
<p>Si (111) slab with closed (<b>a</b>,<b>d</b>) and open (<b>b</b>,<b>d</b>) packing. Top (<b>a</b>,<b>b</b>) (terminating layer only) and side (<b>c</b>,<b>d</b>) view. The edges of the supercell in the corresponding projections are defined by the lines.</p> Full article ">Figure 3
<p>Sphalerite (<b>a</b>) and wurtzite-type (<b>b</b>) ZnO structures. Gray and red balls denote Zn an O, respectively.</p> Full article ">Figure 4
<p>Adsorption of 1 (<b>a</b>,<b>f</b>), 2 (<b>b</b>,<b>d</b>,<b>g</b>,<b>i</b>), and 3 (<b>c</b>,<b>e</b>,<b>h</b>,<b>j</b>) <span class="html-italic">g</span>-ZnO layers on the Si(111) surface. Sphalerite- (<b>a</b>–<b>e</b>) and wurtzite-type (<b>f</b>–<b>j</b>) Si/<span class="html-italic">g</span>-ZnO interface.</p> Full article ">Figure 4 Cont.
<p>Adsorption of 1 (<b>a</b>,<b>f</b>), 2 (<b>b</b>,<b>d</b>,<b>g</b>,<b>i</b>), and 3 (<b>c</b>,<b>e</b>,<b>h</b>,<b>j</b>) <span class="html-italic">g</span>-ZnO layers on the Si(111) surface. Sphalerite- (<b>a</b>–<b>e</b>) and wurtzite-type (<b>f</b>–<b>j</b>) Si/<span class="html-italic">g</span>-ZnO interface.</p> Full article ">Figure 5
<p>Interplanar (<b>a</b>) Zn-O and interlayer (<b>b</b>) Si-O and Zn-O distances in <span class="html-italic">g</span>-ZnO/Si interfaces. Note that in this analysis ZnO layers are numbered from the surface.</p> Full article ">Figure 6
<p>Adhesion energy of ZnO layers deposited on the Si(111) surface.</p> Full article ">
13 pages, 4505 KiB  
Article
Multiscale Modeling of Elastic Waves in Carbon-Nanotube-Based Composite Membranes
by Elaf N. Mahrous, Muhammad A. Hawwa, Abba A. Abubakar and Hussain M. Al-Qahtani
J. Compos. Sci. 2024, 8(7), 258; https://doi.org/10.3390/jcs8070258 - 3 Jul 2024
Viewed by 961
Abstract
A multiscale model is developed for vertically aligned carbon nanotube (CNT)-based membranes that are made for water purification or gas separation. As a consequence of driving fluids through the membranes, they carry stress waves along the fiber direction. Hence, a continuum mixture theory [...] Read more.
A multiscale model is developed for vertically aligned carbon nanotube (CNT)-based membranes that are made for water purification or gas separation. As a consequence of driving fluids through the membranes, they carry stress waves along the fiber direction. Hence, a continuum mixture theory is established for a representative volume element to characterize guided waves propagating in a periodically CNT-reinforced matrix material. The obtained coupled governing equations for the CNT-based composite are found to retain the integrity of the wave propagation phenomenon in each constituent, while allowing them to coexist under analytically derived multiscale interaction parameters. The influence of the mesoscale characteristics on the continuum behavior of the composite is demonstrated by dispersion curves of harmonic wave propagation. Analytically established continuum mixture theory for the CNT-based composite is strengthened by numerical simulations conducted in COMSOL for visualizing mode shapes and wave propagation patterns. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>Schematic of CNT-based membrane for water purification or gas separation.</p> Full article ">Figure 2
<p>CNT-based composite with periodic carbon nanotube distribution.</p> Full article ">Figure 3
<p>Hexagonal and circular cylindrical representative volume elements.</p> Full article ">Figure 4
<p>Finite element mesh used to simulate the RVE: (<b>a</b>) 3D view, (<b>b</b>) top view. RVEs are of equal volume.</p> Full article ">Figure 5
<p>Dispersion curves for a (10,0) zigzag CNT-reinforced SiC matrix (A), and for a (12,6) chiral CNT-reinforced SiC matrix (B).</p> Full article ">Figure 6
<p>Dispersion curves for a (10,0) zigzag CNT-reinforced Ti matrix (C), and for a (12,6) chiral CNT-reinforced Ti matrix (D).</p> Full article ">Figure 7
<p>Three-dimensional views of vibration mode shapes for the RVEs of the four CNT-based composites.</p> Full article ">
19 pages, 3964 KiB  
Article
A Design Optimization Study of Step/Scarf Composite Panel Repairs, Targeting the Maximum Strength and the Minimization of Material Removal
by Spyridon Psarras, Maria-Panagiota Giannoutsou and Vassilis Kostopoulos
J. Compos. Sci. 2024, 8(7), 248; https://doi.org/10.3390/jcs8070248 - 30 Jun 2024
Cited by 1 | Viewed by 944
Abstract
This study aimed to optimize the geometry of composite stepped repair patches, using a parametric algorithm to automate the process due to the complexity of the optimization problem and various factors affecting efficiency. More specifically, the algorithm initially calculates the equivalent strengths of [...] Read more.
This study aimed to optimize the geometry of composite stepped repair patches, using a parametric algorithm to automate the process due to the complexity of the optimization problem and various factors affecting efficiency. More specifically, the algorithm initially calculates the equivalent strengths of the repaired laminate plate according to a max stress criterion, then calculates the dimensions of several elliptical repair patches, taking into account several design methods extracted from the literature. Next, it creates their finite element models and finally, the code conducts an assessment of the examined patch geometries, given specific user-defined criteria. In the end, the algorithm reaches a conclusion about the optimum patch among the designed ones. The algorithm has the potential to run for many different patch geometries. In the current research, five patch geometries were designed and modeled under uniaxial compressive loading at 0°, 45° and 90°. Overall, the code greatly facilitated the design and optimization process and constitutes a useful tool for future research. The results revealed that elliptical stepped patches can offer a near-optimum solution much more efficient than that of the conservative option of the circular patch, in terms of both strength and volume of healthy removed material. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>Flowchart of the algorithm’s main operations.</p> Full article ">Figure 2
<p>Example of patch (<b>a</b>) with the ellipses of all plies parallel to the fibers of 0° and (<b>b</b>) where the ellipse of each ply has its major axis parallel to the fibers of the current ply.</p> Full article ">Figure 3
<p>Flowchart of the first part of the code where the plate’s equivalent strengths are calculated.</p> Full article ">Figure 4
<p>Flowchart of the second part of the code where the dimensions of elliptical patches and the corresponding volume of pristine material loss are calculated.</p> Full article ">Figure 5
<p>Flowchart of the third part of the code where the finite element models of the designed patches on the plate are created.</p> Full article ">Figure 6
<p>Example of (<b>a</b>) the repaired plate model with a near-optimum elliptical patch. On the left, the two sides of the plate; (<b>b</b>) repaired side and (<b>c</b>) back side.</p> Full article ">Figure 7
<p>Flowchart of the fourth part of the code where the post-processing of the results takes place.</p> Full article ">Figure 8
<p>Detailed flowchart of the evaluation of the results and the assessment of the patches.</p> Full article ">Figure 9
<p>The five near-optimum elliptical patches that were designed and examined in the current study. The different geometries are numbered from (I) to (V).</p> Full article ">Figure 10
<p>On the top, illustration of FE simulation for three different case; on the bottom, illustration of the post-processing code extracts of the analyses.</p> Full article ">Figure 11
<p>Results for the five near-optimum patches’ deviation compared to the circular patch strength for compression (<b>a</b>–<b>c</b>) and tension (<b>d</b>–<b>f</b>).</p> Full article ">Figure 12
<p>Results for the five near-optimum patches’ deviation compared to the circular patch r ratio for compression (<b>a</b>–<b>c</b>) and tension (<b>d</b>–<b>f</b>).</p> Full article ">Figure 13
<p>The repair patch procedure from patch creation to testing.</p> Full article ">
14 pages, 2486 KiB  
Article
Thermomechanical Responses and Energy Conversion Efficiency of a Hybrid Thermoelectric–Piezoelectric Layered Structure
by Zhihe Jin and Jiashi Yang
J. Compos. Sci. 2024, 8(5), 171; https://doi.org/10.3390/jcs8050171 - 6 May 2024
Viewed by 1360
Abstract
This paper develops a thermoelectric (TE)–piezoelectric (PE) hybrid structure with the PE layer acting as both a support membrane and a sensor for the TE film for microelectronics applications. The TE and PE layers are assumed to be perfectly bonded mechanically and thermally [...] Read more.
This paper develops a thermoelectric (TE)–piezoelectric (PE) hybrid structure with the PE layer acting as both a support membrane and a sensor for the TE film for microelectronics applications. The TE and PE layers are assumed to be perfectly bonded mechanically and thermally but electrically shielded and insulated with each other. The thermo-electro-mechanical responses of the hybrid bilayer under the TE generator operation conditions are obtained, and the influence of the PE layer on the TE energy conversion efficiency is investigated. The numerical results for a Bi2Te3/PZT-5H bilayer structure show that large compressive stresses develop in both the PE and TE layers. With a decrease in the PE layer thickness, the magnitude of the maximum compressive stress in the PE layer increases whereas the maximum magnitude of the stress in the TE layer decreases. The numerical result of the TE energy conversion efficiency shows that increasing the PE layer thickness leads to lower energy conversion efficiencies. A nearly 40% reduction in the peak efficiency is observed with a PE layer of the same thickness as that of the TE layer. These results suggest that design of TE films with supporting/sensing membranes must consider both aspects of energy conversion efficiency and the thermomechanical reliability of both the TE and PE layers. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>A thermoelectric-piezoelectric bilayer of length <span class="html-italic">L</span> subjected to a temperature differential.</p> Full article ">Figure 2
<p>Temperature distribution in the TE-PE bilayer (<span class="html-italic">t</span><sub>1</sub> = 5 μm).</p> Full article ">Figure 3
<p>Displacement distribution in the TE-PE bilayer (<span class="html-italic">t</span><sub>1</sub> = 5 μm).</p> Full article ">Figure 4
<p>Strain distribution in the TE-PE bilayer (<span class="html-italic">t</span><sub>1</sub> = 5 μm).</p> Full article ">Figure 5
<p>Stress distribution in the PE layer (<span class="html-italic">t</span><sub>1</sub> = 5 μm).</p> Full article ">Figure 6
<p>Electric field in the PE layer (<span class="html-italic">t</span><sub>1</sub> = 5 μm).</p> Full article ">Figure 7
<p>Stress distribution in the TE layer (<span class="html-italic">t</span><sub>1</sub> = 5 μm).</p> Full article ">Figure 8
<p>Stress distribution in the TE layer (<span class="html-italic">t</span><sub>1</sub> = 5 μm).</p> Full article ">Figure 9
<p>Energy conversion efficiency of the TE-PE bilayer structure (<span class="html-italic">t</span><sub>1</sub> = 5 μm).</p> Full article ">
26 pages, 5545 KiB  
Article
Simulation of the Dynamic Responses of Layered Polymer Composites under Plate Impact Using the DSGZ Model
by Huadian Zhang, Arunachalam M. Rajendran, Manoj K. Shukla, Sasan Nouranian, Ahmed Al-Ostaz, Steven Larson and Shan Jiang
J. Compos. Sci. 2024, 8(5), 159; https://doi.org/10.3390/jcs8050159 - 23 Apr 2024
Viewed by 1984
Abstract
This paper presents a numerical study on the dynamic response and impact mitigation capabilities of layered ceramic–polymer–metal (CPM) composites under plate impact loading, focusing on the layer sequence effect. The layered structure, comprising a ceramic for hardness and thermal resistance, a polymer for [...] Read more.
This paper presents a numerical study on the dynamic response and impact mitigation capabilities of layered ceramic–polymer–metal (CPM) composites under plate impact loading, focusing on the layer sequence effect. The layered structure, comprising a ceramic for hardness and thermal resistance, a polymer for energy absorption, and a metal for strength and ductility, is analyzed to evaluate its effectiveness in mitigating the impact loading. The simulations employed the VUMAT subroutine of DSGZ material models within Abaqus/Explicit to accurately represent the mechanical behavior of the polymeric materials in the composites. The VUMAT implementation incorporates the explicit time integration scheme and the implicit radial return mapping algorithm. A safe-version Newton–Raphson method is applied for numerically solving the differential equations of the J2 plastic flow theory. Analysis of the simulation results reveals that specific layer configurations significantly influence wave propagation, leading to variations in energy absorption and stress distribution within the material. Notably, certain layer sequences, such as P-C-M and C-P-M, exhibit enhanced impact mitigation with a superior ability to dissipate and redirect the impact energy. This phenomenon is tied to the interactions between the material properties of the ceramic, polymer, and metal, emphasizing the necessity of precise material characterization and enhanced understanding of the layer sequencing effect for optimizing composite designs for impact mitigation. The integration of empirical data with simulation methods provides a comprehensive framework for optimizing composite designs in high-impact scenarios. In the general fields of materials science and impact engineering, the current research offers some guidance for practical applications, underscoring the need for detailed simulations to capture the high-strain-rate dynamic responses of multilayered composites. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>Flowchart of the VUMAT implementation.</p> Full article ">Figure 2
<p>Schematic model and its Abaqus instance of the plate impact simulation.</p> Full article ">Figure 3
<p>VUMAT subroutine validation for the generalized and modified DSGZ models with material parameters sourced from previous studies [<a href="#B23-jcs-08-00159" class="html-bibr">23</a>,<a href="#B46-jcs-08-00159" class="html-bibr">46</a>,<a href="#B47-jcs-08-00159" class="html-bibr">47</a>,<a href="#B60-jcs-08-00159" class="html-bibr">60</a>,<a href="#B61-jcs-08-00159" class="html-bibr">61</a>].</p> Full article ">Figure 4
<p>Dynamic responses of PC/ABS, Al-6061, Steel-4340, and SiC as a single layer in terms of (<b>a</b>) volumetric strain rate, (<b>b</b>) volumetric strain, (<b>c</b>) equivalent plastic strain, and (<b>d</b>) von Mises stress during the impact compressive wave passing through an element in the mid-plane of the target.</p> Full article ">Figure 5
<p>Dynamic responses of PC/ABS, PC_2, PMMA_2, Al-6061, Steel-4340, and SiC as a single layer represented by (<b>a</b>) free surface velocity and (<b>b</b>) mid-plane stress during the 50 m s<sup>−1</sup> impact.</p> Full article ">Figure 6
<p>Dynamic responses of (<b>a</b>) the interface velocity of the impactor with different first composite layers and (<b>b</b>) the free surface velocity of the backplate with different layer sequences.</p> Full article ">Figure 7
<p>Element energy histories of the front layer with different first composite layers and the backplate with different layer sequences in terms of (<b>a</b>) strain energy and (<b>b</b>) kinetic energy.</p> Full article ">Figure 8
<p>Mid-plane velocity history and corresponding stress at maximum velocity of the protected target for different layer sequences, with no initial gap to the armor; pure ceramic, polymer, and metal layers are plotted as the reference using dashed lines or dashed outlines.</p> Full article ">Figure 9
<p>Mid-plane velocity history and corresponding stress at maximum velocity of the protected target for different layer sequences, with the initial gap distances of (<b>a</b>) 1.0, (<b>b</b>) 2.0, and (<b>c</b>) 3.0 mm to the armor; pure ceramic, polymer, and metal layers are plotted as the reference using dashed lines or dashed outlines.</p> Full article ">
15 pages, 2598 KiB  
Article
Effects of Topological Parameters on Thermal Properties of Carbon Nanotubes via Molecular Dynamics Simulation
by Lida Najmi and Zhong Hu
J. Compos. Sci. 2024, 8(1), 37; https://doi.org/10.3390/jcs8010037 - 22 Jan 2024
Cited by 6 | Viewed by 2530
Abstract
Due to their unique properties, carbon nanotubes (CNTs) are finding a growing number of applications across multiple industrial sectors. These properties of CNTs are subject to influence by numerous factors, including the specific chiral structure, length, type of CNTs used, diameter, and temperature. [...] Read more.
Due to their unique properties, carbon nanotubes (CNTs) are finding a growing number of applications across multiple industrial sectors. These properties of CNTs are subject to influence by numerous factors, including the specific chiral structure, length, type of CNTs used, diameter, and temperature. In this topic, the effects of chirality, diameter, and length of single-walled carbon nanotubes (SWNTs) on the thermal properties were studied using the reverse non-equilibrium molecular dynamics (RNEMD) method and the Tersoff interatomic potential of carbon–carbon based on the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). For the shorter SWNTs, the effect of chirality on the thermal conductivity is more obvious than for longer SWNTs. Thermal conductivity increases with increasing chiral angle, and armchair SWNTs have higher thermal conductivity than that of zigzag SWNTs. As the tube length becomes longer, the thermal conductivity increases while the effect of chirality on the thermal conductivity decreases. Furthermore, for SWNTs with longer lengths, the thermal conductivity of zigzag SWNTs is higher than that of the armchair SWNTs. Thermal resistance at the nanotube–nanotube interfaces, particularly the effect of CNT overlap length on thermal resistance, was studied. The simulation results were compared with and in agreement with the experimental and simulation results from the literature. The presented approach could be applied to investigate the properties of other advanced materials. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>Reverse non-equilibrium molecular dynamics (RNEMD) approach employed to compute the thermal conductivity of SWNTs.</p> Full article ">Figure 2
<p>Schematic diagram of the chirality of a graphene hexagonal lattice with lattice vectors <b><span class="html-italic">a</span></b><sub>1</sub> and <b><span class="html-italic">a</span></b><sub>2</sub>.</p> Full article ">Figure 3
<p>Thermal conductivity versus tube length of zigzag and armchair SWNTs with constant diameter (0.65 nm) at room temperature (300 K).</p> Full article ">Figure 4
<p>Thermal conductivity convergence study by time step.</p> Full article ">Figure 5
<p>Chiral angle-dependent thermal conductivity of SWNTs with different diameters and a tube length of 5 nm.</p> Full article ">Figure 6
<p>Comparison of the thermal conductivities of single-walled carbon nanotubes with the same chiral angles and different diameters at a fixed length of 5 nm.</p> Full article ">Figure 7
<p>The diagram illustrates a setup comprising three adjacent CNTs used to explore the thermal resistance between the neighboring nanotubes with the overlap of <span class="html-italic">a</span>.</p> Full article ">Figure 8
<p>Thermal resistance, <span class="html-italic">R</span>, at the CNT–CNT interface as a function of the horizontal overlap (<span class="html-italic">a</span>), where <span class="html-italic">h</span> is set to 0.4 nm.</p> Full article ">
14 pages, 3621 KiB  
Article
First Principle Study of Structural, Electronic, Optical Properties of Co-Doped ZnO
by Ahmed Soussi, Redouane Haounati, Abderrahim Ait hssi, Mohamed Taoufiq, Abdellah Asbayou, Abdeslam Elfanaoui, Rachid Markazi, Khalid Bouabid and Ahmed Ihlal
J. Compos. Sci. 2023, 7(12), 511; https://doi.org/10.3390/jcs7120511 - 7 Dec 2023
Cited by 10 | Viewed by 2342
Abstract
In this theoretical study, the electronic, structural, and optical properties of copper-doped zinc oxide (CZO) were investigated using the full-potential linearized enhanced plane wave method (FP-LAPW) based on the density functional theory (DFT). The Tran–Blaha modified Becke–Johnson exchange potential approximation (TB-mBJ) was employed [...] Read more.
In this theoretical study, the electronic, structural, and optical properties of copper-doped zinc oxide (CZO) were investigated using the full-potential linearized enhanced plane wave method (FP-LAPW) based on the density functional theory (DFT). The Tran–Blaha modified Becke–Johnson exchange potential approximation (TB-mBJ) was employed to enhance the accuracy of the electronic structure description. The introduction of copper atoms as donors in the ZnO resulted in a reduction in the material’s band gap from 2.82 eV to 2.72 eV, indicating enhanced conductivity. This reduction was attributed to the Co-3d intra-band transitions, primarily in the spin-down configuration, leading to increased optical absorption in the visible range. The Fermi level of the pure ZnO shifted towards the conduction band, indicating metal-like characteristics in the CZO. Additionally, the CZO nanowires displayed a significant blue shift in their optical properties, suggesting a change in the energy band structure. These findings not only contribute to a deeper understanding of the CZO’s fundamental properties but also open avenues for its potential applications in optoelectronic and photonic devices, where tailored electronic and optical characteristics are crucial. This study underscores the significance of computational techniques in predicting and understanding the behavior of doped semiconductors, offering valuable insights for the design and development of novel materials for advanced electronic applications. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>Zinc oxide (ZnO) unit cell in the F63mc space group.</p> Full article ">Figure 2
<p>The total energy variation as a function of volume for the ZnO through a systematic variation of ±5%.</p> Full article ">Figure 3
<p>The total energy variation as a function of c/a for the ZnO through a systematic variation of ±15%.</p> Full article ">Figure 4
<p>The band structures of ZnO (<b>a</b>) with 2% co-doping (<b>b</b>,<b>c</b>) along high-symmetry lines in the Brillouin zone using the TB-mBJ approximation.</p> Full article ">Figure 5
<p>The densities of states of ZnO (<b>a</b>) with 2% co-doping (<b>b</b>,<b>c</b>) along high-symmetry lines in the Brillouin zone using the TB-mBJ approximation.</p> Full article ">Figure 6
<p>The refractive index calculated for the ZnO and CZO using the TB-mBJ approximation.</p> Full article ">Figure 7
<p>The extinction coefficient calculated for the ZnO and CZO using the TB-mBJ approximation.</p> Full article ">Figure 8
<p>The reflectivity calculated for the ZnO and CZO using the TB-mBJ approximation.</p> Full article ">Figure 9
<p>The absorption coefficient calculated for the ZnO and CZO using the TB-mBJ approximation.</p> Full article ">Figure 10
<p>The transmittance calculated for the ZnO and CZO using the TB-mBJ approximation.</p> Full article ">
14 pages, 12851 KiB  
Article
Mechanics and Crack Analysis of Irida Graphene Bilayer Composite: A Molecular Dynamics Study
by Jianyu Li, Mingjun Han, Shuai Zhao, Teng Li, Taotao Yu, Yinghe Zhang, Ho-Kin Tang and Qing Peng
J. Compos. Sci. 2023, 7(12), 490; https://doi.org/10.3390/jcs7120490 - 27 Nov 2023
Cited by 3 | Viewed by 1803
Abstract
In this paper, we conducted molecular dynamics simulations to investigate the mechanical properties of double-layer and monolayer irida graphene (IG) structures and the influence of cracks on them. IG, a new two-dimensional material comprising fused rings of 3-6-8 carbon atoms, exhibits exceptional electrical [...] Read more.
In this paper, we conducted molecular dynamics simulations to investigate the mechanical properties of double-layer and monolayer irida graphene (IG) structures and the influence of cracks on them. IG, a new two-dimensional material comprising fused rings of 3-6-8 carbon atoms, exhibits exceptional electrical and thermal conductivity, alongside robust structural stability. We found the fracture stress of the irida graphene structure on graphene sheet exceeds that of the structure comprising solely irida graphene. Additionally, the fracture stress of bilayer graphene significantly surpasses that of bilayer irida graphene. We performed crack analysis in both IG and graphene and observed that perpendicular cracks aligned with the tensile direction result in decreased fracture stress as the crack length increases. Moreover, we found that larger angles in relation to the tensile direction lead to reduced fracture stress. Across all structures, 75° demonstrated the lowest stress and strain. These results offer valuable implications for utilizing bilayer and monolayer IG in the development of advanced nanoscale electronic devices. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>Schematic diagram of (<b>a</b>) the atomic structure of irida graphene, (<b>b</b>) bilayer irida graphene structure and (<b>c</b>) cracks, with angles of 0°, 45°, and 90° to the tensile direction. The distance between layers is calculated using their relative coordinates.</p> Full article ">Figure 2
<p>Tensile stress–strain curves under different numbers of atoms: (<b>a</b>) monolayer graphene (GE), (<b>b</b>) monolayer irida graphene (IG), (<b>c</b>) comparison of stress–strain curves of two structures with box size of 200 × 200 Å<sup>2</sup>.</p> Full article ">Figure 3
<p>Tensile stress–strain curves under different atoms: (<b>a</b>) double-layer graphene (GE/GE), (<b>b</b>) double-layer irida graphene (IG/IG), (<b>c</b>) the combination of one layer of graphene and one layer of iridium graphene structure (GE/IG), (<b>d</b>) comparison of stress–strain curves of three structures with box size of 200 × 200 Å<sup>2</sup>.</p> Full article ">Figure 4
<p>Fracture stress and strain at different box size: (<b>a</b>) relationship between fracture stress and box size, (<b>b</b>) relationship between fracture strain and box size.</p> Full article ">Figure 5
<p>Tensile stress–strain curves under different numbers of atoms: (<b>a</b>) monolayer graphene (GE), (<b>b</b>) monolayer irida graphene (IG).</p> Full article ">Figure 6
<p>Tensile stress–strain curves of cracks of different lengths when the crack is 90° to the x-axis: (<b>a</b>) bilayer graphene (GE/GE), (<b>b</b>) double-layer irida graphene (IG/IG), (<b>c</b>) the composite structure formed by combining GE and IG (GE/IG).</p> Full article ">Figure 7
<p>Fracture process of (<b>a</b>) GE/GE, (<b>b</b>) IG/IG, and (<b>c</b>) GE/IG.</p> Full article ">Figure 8
<p>Tensile stress–strain curves under different angles of cracks: (<b>a</b>) monolayer graphene, (<b>b</b>) monolayer irida graphene, (<b>c</b>) bilayer graphene, (<b>d</b>) bilayer irida graphene.</p> Full article ">Figure 9
<p>Tensile stress–strain curves under different angles of cracks for the composite structure formed by combining GE and IG (GE/IG).</p> Full article ">Figure 10
<p>Fracture stress and strain at different crack angles: (<b>a</b>) relationship between fracture stress and crack angle, (<b>b</b>) relationship between fracture strain and crack angle.</p> Full article ">
15 pages, 6451 KiB  
Article
Atomic Insights into the Structural Properties and Displacement Cascades in Ytterbium Titanate Pyrochlore (Yb2Ti2O7) and High-Entropy Pyrochlores
by M. Mustafa Azeem and Qingyu Wang
J. Compos. Sci. 2023, 7(10), 413; https://doi.org/10.3390/jcs7100413 - 5 Oct 2023
Viewed by 1707
Abstract
Pyrochlore oxides (A2B2O7) are potential nuclear waste substrate materials due to their superior radiation resistance properties. We performed molecular dynamics simulations to study the structural properties and displacement cascades in ytterbium titanate pyrochlore ( [...] Read more.
Pyrochlore oxides (A2B2O7) are potential nuclear waste substrate materials due to their superior radiation resistance properties. We performed molecular dynamics simulations to study the structural properties and displacement cascades in ytterbium titanate pyrochlore (Yb2Ti2O7) and high-entropy alloys (HEPy), e.g., YbYTiZrO7, YbGdTiZrO7, and Yb0.5Y0.5Eu0.5Gd0.5TiZrO7. We computed lattice constants (LC) (ao) and threshold displacement energy (Ed). Furthermore, the calculation for ao and ionic radius (rionic) were performed by substituting a combination of cations at the A and B sites of the original pyrochlore structure. Our simulation results have demonstrated that the lattice constant is proportional to the ionic radius, i.e., ao α rionic. Moreover, the effect of displacement cascades of recoils of energies 1 keV, 2 keV, 5 keV, and 10 keV in different crystallographic directions ([100], [110], [111]) was studied. The number of defects is found to be proportional to the energy of incident primary knock-on atoms (PKA). Additionally, the Ed of pyrochlore exhibits anisotropy. We also observed that HEPy has a larger Ed as compared with Yb2Ti2O7. This establishes that Yb2Ti2O7 has characteristics of lower radiation damage resistance than HEPy. Our displacement cascade simulation result proposes that HEPy alloys have more tendency for trapping defects. This work will provide atomic insights into developing substrate materials for nuclear waste applications. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
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<p>Schematic representation of the computational model and a unit cell of pyrochlore, (<b>a</b>) Snapshot of a computational unit cell model, <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>16</mn> </mrow> </msub> <msub> <mrow> <mi>Ti</mi> </mrow> <mrow> <mn>16</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>56</mn> </mrow> </msub> </mrow> </semantics></math>, (<b>b</b>) Generic representation of a unit cell of pyrochlore <math display="inline"><semantics> <mrow> <msub> <mrow> <mi mathvariant="normal">A</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">B</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>7</mn> </mrow> </msub> </mrow> </semantics></math> where A and B are transition metals [<a href="#B43-jcs-07-00413" class="html-bibr">43</a>], (<b>c</b>) labeled structure of <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>16</mn> </mrow> </msub> <msub> <mrow> <mi>Ti</mi> </mrow> <mrow> <mn>16</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>56</mn> </mrow> </msub> </mrow> </semantics></math>, (<b>d</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>8</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">Y</mi> </mrow> <mrow> <mn>8</mn> </mrow> </msub> <mi>Ti</mi> </mrow> <mrow> <mn>8</mn> </mrow> </msub> <msub> <mrow> <msub> <mrow> <mi mathvariant="normal">Z</mi> <mi mathvariant="normal">r</mi> </mrow> <mrow> <mn>8</mn> </mrow> </msub> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>56</mn> </mrow> </msub> </mrow> </semantics></math>, (<b>e</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>8</mn> </mrow> </msub> <msub> <mrow> <mi>Gd</mi> </mrow> <mrow> <mn>8</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">Z</mi> <mi mathvariant="normal">r</mi> </mrow> <mrow> <mn>8</mn> </mrow> </msub> <mi>Ti</mi> </mrow> <mrow> <mn>8</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>56</mn> </mrow> </msub> </mrow> </semantics></math>, and (<b>f</b>) <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>4</mn> </mrow> </msub> <msub> <mrow> <msub> <mrow> <msub> <mrow> <mi mathvariant="normal">Y</mi> </mrow> <mrow> <mn>4</mn> </mrow> </msub> <mi>Gd</mi> </mrow> <mrow> <mn>4</mn> </mrow> </msub> <mi>Eu</mi> </mrow> <mrow> <mn>4</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">Z</mi> <mi mathvariant="normal">r</mi> </mrow> <mrow> <mn>8</mn> </mrow> </msub> <msub> <mrow> <mi>Ti</mi> </mrow> <mrow> <mn>8</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>56</mn> </mrow> </msub> </mrow> </semantics></math> equivalent of <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>0.5</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">Y</mi> </mrow> <mrow> <mn>0.5</mn> </mrow> </msub> <msub> <mrow> <mi>Eu</mi> </mrow> <mrow> <mn>0.5</mn> </mrow> </msub> <msub> <mrow> <mi>Gd</mi> </mrow> <mrow> <mn>0.5</mn> </mrow> </msub> <mi>ZrTi</mi> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>7</mn> </mrow> </msub> </mrow> </semantics></math>. The subscript indicates the number of particular elements in the unit cell.</p> Full article ">Figure 2
<p>Potential energy (<span class="html-italic">V<sub>ij</sub></span>) as a function of distance (<span class="html-italic">r<sub>ij</sub></span>) between pairs fitted by splined ZBL and Buckingham for (<b>a</b>) Yb-O, (<b>b</b>) O-O, and (<b>c</b>) Ti-O.</p> Full article ">Figure 3
<p>Relationship between system energy as a function of LC in Yb<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub>.</p> Full article ">Figure 4
<p>XRD pattern of <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi>Ti</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>7</mn> </mrow> </msub> </mrow> </semantics></math>, YbYTiZrO<sub>7</sub>, YbGdTiZrO<sub>7</sub>, and <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>0.5</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">Y</mi> </mrow> <mrow> <mn>0.5</mn> </mrow> </msub> <msub> <mrow> <mi>Eu</mi> </mrow> <mrow> <mn>0.5</mn> </mrow> </msub> <msub> <mrow> <mi>Gd</mi> </mrow> <mrow> <mn>0.5</mn> </mrow> </msub> <mi>TiZr</mi> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>7</mn> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 5
<p>E<sub>d</sub> as a function of incident PKA for <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi>Ti</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>7</mn> </mrow> </msub> <mtext> </mtext> </mrow> </semantics></math> along with bombardment directions.</p> Full article ">Figure 6
<p>Number of defects (<math display="inline"><semantics> <mrow> <msub> <mrow> <mi>N</mi> </mrow> <mrow> <mi>d</mi> <mi>e</mi> <mi>f</mi> <mi>e</mi> <mi>c</mi> <mi>t</mi> <mi>s</mi> </mrow> </msub> <mo>)</mo> </mrow> </semantics></math> as a function of time under different energy PKA damage of <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi>Ti</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>7</mn> </mrow> </msub> </mrow> </semantics></math> bombarded with Yb ions of different energies.</p> Full article ">Figure 7
<p>Displacement cascades in <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi>Ti</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>7</mn> </mrow> </msub> </mrow> </semantics></math> bombarded with 5 keV Yb at different timesteps. Blue colors are vacancies whereas purple is interstitials.</p> Full article ">Figure 8
<p>Number of surviving defects as a function of (<b>a</b>) Time and (<b>b</b>) inclination angle of incident 5 keV Yb in <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi>Ti</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>7</mn> </mrow> </msub> </mrow> </semantics></math>.</p> Full article ">Figure 9
<p>The number of defects of different types of atoms at an inclination of (<b>a</b>) 55° and (<b>b</b>) 85°.</p> Full article ">Figure 10
<p>Evolution of Displacement cascades in <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi>Ti</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mrow> <mn>7</mn> <mtext> </mtext> </mrow> </mrow> </msub> </mrow> </semantics></math> <math display="inline"><semantics> <mrow> <mi>YbYTiZr</mi> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>7</mn> </mrow> </msub> </mrow> </semantics></math>, <math display="inline"><semantics> <mrow> <mi>YbGdTiZr</mi> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>7</mn> </mrow> </msub> </mrow> </semantics></math>, and <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>0.5</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">Y</mi> </mrow> <mrow> <mn>0.5</mn> </mrow> </msub> <msub> <mrow> <mi>Eu</mi> </mrow> <mrow> <mn>0.5</mn> </mrow> </msub> <msub> <mrow> <mi>Gd</mi> </mrow> <mrow> <mn>0.5</mn> </mrow> </msub> <mi>TiZr</mi> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mn>7</mn> </mrow> </msub> </mrow> </semantics></math> at timesteps 0.3 ps and 0.9 ps. The number of surviving defects considerably reduced with the increase of alloying constituent.</p> Full article ">Figure 11
<p>Defect evolution as function time in undoped <math display="inline"><semantics> <mrow> <msub> <mrow> <mi>Yb</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi>Ti</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msub> <msub> <mrow> <mi mathvariant="normal">O</mi> </mrow> <mrow> <mrow> <mn>7</mn> </mrow> </mrow> </msub> </mrow> </semantics></math> and HEPy doped with Y, Gd, and YGdEu at the A sites.</p> Full article ">
26 pages, 35708 KiB  
Article
Numerical Modeling of Single-Lap Shear Bond Tests for Composite-Reinforced Mortar Systems
by Rossana Dimitri, Martina Rinaldi, Marco Trullo and Francesco Tornabene
J. Compos. Sci. 2023, 7(8), 329; https://doi.org/10.3390/jcs7080329 - 14 Aug 2023
Cited by 3 | Viewed by 1535
Abstract
The large demand of reinforcement systems for the rehabilitation of existing concrete and masonry structures, has recently increased the development of innovative methods and advanced systems where the structural mass and weight are reduced, possibly avoiding steel reinforcements, while using non-invasive and reversible [...] Read more.
The large demand of reinforcement systems for the rehabilitation of existing concrete and masonry structures, has recently increased the development of innovative methods and advanced systems where the structural mass and weight are reduced, possibly avoiding steel reinforcements, while using non-invasive and reversible reinforcements made of pre-impregnated fiber nets and mortars in the absence of cement, commonly known as composite-reinforced mortars (CRMs). To date, for such composite materials, few experimental studies have been performed. Their characterization typically follows the guidelines published by the Supreme Council of Public Works. In such a context, the present work aims at studying numerically the fracturing behavior of CRM single-lap shear tests by implementing a cohesive zone model and concrete damage plasticity, in a finite element setting. These specimens are characterized by the presence of a mortar whose mechanical behavior has been defined by means of an analytical approximation based on exponential or polynomial functions. Different fracturing modes are studied numerically within the CRM specimen, involving the matrix and reinforcement phases, as well as the substrate-to-CRM interface. Based on a systematic investigation, the proposed numerical modeling is verified to be a useful tool to predict the response of the entire reinforcement system, in lieu of more costly experimental tests, whose results could be useful for design purposes and could serve as reference numerical solutions for further analytical/experimental investigations on the topic. Full article
(This article belongs to the Special Issue Theoretical and Computational Investigation on Composite Materials)
►▼ Show Figures

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Figure 1
<p>Concrete yield surface.</p> Full article ">Figure 2
<p>Constitutive relation in compression.</p> Full article ">Figure 3
<p>Behavior in tension.</p> Full article ">Figure 4
<p>Pure mode constitutive laws: (<b>a</b>) mode II or mode III; (<b>b</b>) mode I.</p> Full article ">Figure 5
<p>Single-lap direct shear test setup.</p> Full article ">Figure 6
<p>Constitutive relations in compression (<b>a</b>) and tension (<b>b</b>) as predicted in Ref. [<a href="#B35-jcs-07-00329" class="html-bibr">35</a>] and by our exponential approximation.</p> Full article ">Figure 7
<p>Constitutive relations in compression (<b>a</b>) and tension (<b>b</b>) as predicted in Mazzucco et al. [<a href="#B35-jcs-07-00329" class="html-bibr">35</a>] and by our polynomial approximation.</p> Full article ">Figure 8
<p>Analytical approximation from polynomial and exponential equations of a specimen in compression (<b>a</b>) and tension (<b>b</b>).</p> Full article ">Figure 9
<p>Detail of the fiber net in principal directions.</p> Full article ">Figure 10
<p>Reduced specimen. Geometric dimensions in mm.</p> Full article ">Figure 11
<p>Matrix tensile damage contour for a polynomial (<b>a</b>) and exponential (<b>b</b>) approximation of a reduced specimen with wet fibers.</p> Full article ">Figure 12
<p>Matrix tensile damage contour for a polynomial (<b>a</b>) and exponential (<b>b</b>) approximation of a reduced specimen with dry fibers.</p> Full article ">Figure 13
<p>Comparison of the results for wet (<b>a</b>) and dry (<b>b</b>) carbon fibers.</p> Full article ">Figure 14
<p>Detail of the fiber–matrix cohesive interfaces.</p> Full article ">Figure 15
<p>Matrix tensile damage contour for a polynomial (<b>a</b>) and exponential (<b>b</b>) approximation of a reduced specimen with a fiber–matrix cohesive interface and wet fibers.</p> Full article ">Figure 16
<p>Load vs. slip response of the specimen modeled with a cohesive matrix–fiber interface.</p> Full article ">Figure 17
<p>Geometric properties of the specimen (dimensions in mm).</p> Full article ">Figure 18
<p>Matrix tensile damage contour for a polynomial (<b>a</b>) and exponential (<b>b</b>) approximation.</p> Full article ">Figure 19
<p>Matrix tensile damage contour for a polynomial (<b>a</b>) and exponential (<b>b</b>) approximation.</p> Full article ">Figure 20
<p>Comparison of the results for wet (<b>a</b>) and dry (<b>b</b>) carbon fibers.</p> Full article ">Figure 21
<p>Matrix tensile damage contour for a polynomial (<b>a</b>) and exponential (<b>b</b>) approximation.</p> Full article ">Figure 22
<p>Load vs. slip response of the specimen modeled with a cohesive matrix–fiber interface.</p> Full article ">Figure 23
<p>Geometric properties of the specimen (dimensions in mm).</p> Full article ">Figure 24
<p>Matrix tensile damage contour for a polynomial (<b>a</b>) and exponential (<b>b</b>) approximation.</p> Full article ">Figure 25
<p>Matrix tensile damage contour for a polynomial (<b>a</b>) and exponential (<b>b</b>) approximation.</p> Full article ">Figure 26
<p>Comparison of the results for wet (<b>a</b>) and dry (<b>b</b>) carbon fibers.</p> Full article ">Figure 27
<p>Detail of the matrix–substrate cohesive interfaces.</p> Full article ">Figure 28
<p>Contour plot evolution of the shear stress in the direction of the applied load—detail of the cohesive interface for the reduced specimen.</p> Full article ">Figure 29
<p>Global response of the specimen with a cohesive matrix–substrate interface.</p> Full article ">Figure 30
<p>Contour plot evolution of the shear stresses in the direction of the applied load—detail of the cohesive interface.</p> Full article ">Figure 30 Cont.
<p>Contour plot evolution of the shear stresses in the direction of the applied load—detail of the cohesive interface.</p> Full article ">Figure 31
<p>Global response of the specimen with a cohesive matrix–substrate interface.</p> Full article ">
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