Search Results (1,589)

Flexible pipes can be subjected to extreme bending load during installation and in situ operations, as well as high pressure from oil and gas field production fluids. Although field experience shows that the unlocking of the pressure armour layer is a rare failure mode, its consequences are potentially catastrophic. To investigate the unlocking mechanism of the pressure armour layer, a 3D nonlinear finite element model is developed, which contains three layers: a pressure armour layer with a “Zeta” shape cross-section, a polymer layer, and an analytical cylindrical surface representing the radial support from the carcass. The analysis is carried out with the ABAQUS Dynamic Explicit solver using a semi-automatic mass scaling factor. The study focuses on the possibility of pressure armour unlocking due to bending load, where the effects of geometric features of the pressure armour layer and internal pressure value on unlocking are investigated by varying corresponding parameters. The influence of these variables are discussed at the end. Ultimately, in conjunction with the numerical analysis results, critical reflections on the shortcomings of the model and suggestions for improvement are presented based on the numerical analysis results. Full article

Plate structures are the main components of offshore platforms and ships in engineering applications. The vibration control of the low-frequency mode of plate structures has always been a meaningful research object in marine science and engineering. Due to their low cost and good performance, dynamic vibration absorbers are widely used. To enhance the design efficiency of dynamic vibration absorbers, a mathematical model was developed for plates with dynamic vibration absorbers under different boundary constraints. To overcome the discontinuity of the displacement function, auxiliary series were introduced. In addition, the efficiency of resolving the plate structure’s equivalent mass was significantly improved compared with when using FEM software Abaqus 6.14. The validity of the proposed mathematical model was confirmed in comparison with related studies, the FEM results, and the experimental results. Considering the mathematical model and design approach proposed in the current paper, more research on the vibration control of plates subjected to clamped and elastic boundary conditions should be performed. The mathematical model and findings in the design process may have positive implications for the control of the vibration of plate structures in marine science and engineering. Full article

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

Currently, fiber-reinforced concrete, as a building material, is widely used in highway bridges and tunnel linings, and it has become a global research hotspot, with indoor tests, numerical simulations, performance studies, and application scenarios surrounding it. Many researchers have conducted experiments and analyses on the damage patterns of fiber-reinforced concrete under different conditions. However, there is relatively little research on the mechanical properties of fiber-reinforced concrete that already contains initial damage. This article establishes a micro-model composed of aggregates, mortar, and interface layers using MATLAB. It introduces the CDP (Concrete Damage Plasticity) constitutive equation for fiber-reinforced concrete and uses the least squares method to fit and validate the equation. After model validation, uniaxial compression tests are conducted on models with different initial porosities using the ABAQUS (2023) software, resulting in changes in crack damage, peak stress, and elastic modulus mechanical properties. The conclusions are as follows: The improved characteristic structure curve using the least squares method fits the experimental results well, and the rationality of the algorithm was verified by comparing it with physical tests. As the porosity increased from 2% to 8%, the peak stress decreased from 98.6% to 70.5% compared to non-porous fiber concrete with a significant rate of decrease of about 30%. After considering the strain rate, the peak stress increased slowly with increasing strain rate, but the elastic modulus increased at a significant rate, with a 1.26 times higher elastic modulus at a strain rate of 10⁰ than at a strain rate of 10⁻². This result provides a certain theoretical basis for the mechanical properties and damage modes of fiber-containing concrete in practical engineering. Full article

In this study, numerical simulations using the Abaqus finite element model were performed to evaluate the effects of incorporating waste tyres of varying sizes into the base layer as part of a coupled tyre–pavement structure. The tyre-reinforced structure demonstrated superior deformation resilience, attributed to the hyperelastic properties of tyre rubber, underscoring its potential for applications where deformation recovery is essential. For achieving a uniform settlement, the entire tyre stacking scheme is recommended, whereas the one-third tyre configuration is ideal for minimising displacement. The one-half tyre configuration provides a balanced approach, optimising resource utilisation for structures with moderate performance requirements. The inclusion of tyres increases the equivalent stress within the cement-stabilised gravel layer beneath the tyre, and this effect is less pronounced with smaller tyre sizes. Notably, the projected portion of the tyre tread enhances the bearing capacity of the base structure, improving the load distribution and overall structural performance. The middle and bottom surface layers were identified as the most critical for controlling deformation and stress distribution, while a moderate modulus is advised for the surface course to achieve a balance between deformation control and stress uniformity. The integration of high-modulus layers with tyre reinforcement offers an optimised solution for both deformation management and stress distribution. This study highlights the potential of tyre-reinforced pavements as an innovative and sustainable construction practice, particularly suited for light to moderate traffic conditions. Further research is recommended to explore the long-term environmental and economic benefits, as well as the impacts of tyre composition and ageing on performance. Full article

A novel L-shaped concrete-filled steel tube (CFST) column is proposed in this study. A finite element model of the column is developed using ABAQUS software to analyze its load transfer mechanism and axial compressive behavior. The effects of factors such as the steel strength, steel tube thickness, support plate configuration, and perforation of the support plates on the compressive performance of the column are investigated. The simulation results reveal that the column exhibits robust axial compressive performance. Increasing the steel strength and incorporating support plates (SP) effectively enhance the column’s compressive bearing capacity and positively influence the bearing capacity coefficient (δ). However, increasing the steel tube thickness results in a reduction in δ, indicating that the rate of increase in the bearing capacity diminishes with increasing thickness. The failure mode is primarily characterized by local buckling in the midsection of the steel tube’s concave corner. Measures such as increasing the steel strength and tube thickness and the use of support plates help to mitigate buckling at the concave corner, improve concrete confinement, and enhance the overall compressive performance of the column. Full article

Based on the Zhuyuan–Bailonggang sewage interconnection pipe project in Shanghai, the ABAQUS finite element software was used in numerical simulations to study the fine control of stratum disturbances caused by pipe jacking parameter deviation in soft soil areas. Combining the simulation results with onsite measured data, the Peck formula was used to predict surface settlement. The results indicate the following: (1) The jacking speed and face pressure are negatively correlated with surface settlement. Under the maximum positive deviation and negative deviations in the jacking speed, after the tail passes through the monitoring section D₀ 16 ring, the maximum value of settlement at point B8 increases by 21.6% and decreases by 12.8%, respectively. Increasing the jacking speed increases the area with stress change ratio R < 0 at monitoring section D₀, and the arch foot at the tail of the pipe jacking machine decreases the surface settlement. In contrast, when the face pressure deviates from its average value, the variation range is less than 1%. (2) The pipe slurry coefficient and surface subsidence are positively correlated. Under the maximum positive deviation and the maximum negative deviation, the tail passes through the monitoring section D₀ 16 ring, and the maximum settlement value at B8 decreases by 4.9% and increases by 16.5%, respectively. The increase in the coefficient reduces the area with R < 0 at D₀ and increases the surface settlement. (3) In the order of descending strength, surface settlement is affected by the jacking speed, slurry friction coefficient, and face pressure. (4) To predict the maximum surface settlement value due to deviations in the jacking parameters, the Peck formula was modified using a correction factor $\alpha$ ranging from 0.6 to 3.0 and a settlement trough width correction factor $\beta$ ranging from 1.6 to 4.0. The modified prediction curve is in closer agreement with the actual conditions. Full article

Thin-walled structures are extensively utilized in construction because of their lightweight nature and excellent energy absorption efficiency, especially under dynamic loads. Improving the energy-absorbing performance of thin-walled structures by inspiring natural multi-cell designs is a sufficient approach. This paper investigates the energy-absorbing characteristics of variable novel cross-section designs of thin-walled structures subjected to oblique impact loading. Straight and tapered types with seven cross-sectional designs of novel thin-walled structures were studied. The nonlinear ABAQUS/Explicit software 6.13 version was implemented to analyze the crashworthiness behaviors for the proposed variable cross-section designs under different loading angles. The crushing behaviors of the proposed thin-walled structures were examined for various wall thicknesses of 0.5 mm, 1.5 mm, and 2.5 mm and impact loading angles of 0°, 15°, 30°, and 45°. It was determined that the energy-absorbing characteristics of novel thin-walled structures can be efficiently controlled by varying two geometries and seven cross-section designs. A multi-criteria decision-making method (MCDM) using a complex proportional assessment method (COPRAS) was performed to select the optimum thin-walled structures with cross-section designs. It was shown that a tapered square thin-walled structure with 2.5 mm thickness had the best crashworthiness performances with energy absorption (EA) of 11.01 kJ and specific energy absorption (SEA) of 20.32 kJ/kg under a 30° impact angle. Moreover, the results indicated that the EA of the thin-walled structure decreased with the increase in the impact loading angle. In addition, with the increase in the impact loading angle, the peak crushing force (PCF) decreased and reflected the reduction in energy absorbed at a larger angle. The MCDM method in conjunction with the COPRAS method is proposed; it provides valuable insights for safer and more resilient building construction. Full article

The development of modern solid rocket technology with high-performance and high-loading ratio propellants places higher requirements on the safety and stability of the solid rocket motor. The propellant of the solid rocket motor will creep during long-term vertical storage, which may adversely affect its regular operation. The ignition transient process is a critical phase in the operation of solid rocket motors. The Abaqus v.2022 finite element simulation software is used to analyze the ignition transient under propellant creep conditions and obtain the deformed combustion chamber profile. Then, we use a high-precision finite volume solver developed independently to simulate the flow field during the ignition process. In the simulation, we adopt the surface temperature of the propellant column reaching the ignition threshold as the ignition criterion, considering the heat transfer process of the propellant column instead of using the near-wall gas temperature to obtain the set temperature. Simulation results under different creep conditions reveal that the deformation of the propellant grains progressively intensifies as the solid rocket motor’s storage duration increases. This leads to a delayed initial ignition time of the propellant, an advancement of the overall ignition transient process, and an increased pressurization rate during ignition, which can affect the structure and regular operation of the motor. The research results provide design guidance and theoretical support for the design and life prediction of solid rocket motors. Full article

The double-arrow hollow cylinder (DAHC) has excellent mechanical properties under axial compression loads due to its negative Poisson ratio structure. To improve finite element simulation efficiency for parameter optimization analysis, an automatic modeling program for DAHC negative Poisson ratio structures was developed on the ABAQUS platform using Python. The sample was manufactured using selective laser melting additive manufacturing based on the solid model and then simulated using the finite element method. The accuracy of the automatic modeling method was confirmed by comparing load–displacement curves and deformation cloud images with static compression test results. The DAHC automatic modeling program based on Python can reduce workload during parameter optimization analysis and improve finite element analysis efficiency. Full article

Adhesively bonded joints are essential in the aeronautical industry, offering benefits such as weight reduction and enhanced sustainability. However, certifying these joints is challenging due to unreliable methods for assessing their strength and the development of predictive models for fatigue-driven disbonding remains an ongoing effort. This manuscript presents the implementation and validation of a cohesive zone model for studying high-cycle fatigue disbonding under Mode I and Mixed-Mode loading. The model was integrated into the commercial finite element analysis software Abaqus using user-defined material subroutine (UMAT). Two modelling approaches were investigated: one replacing the adhesive with a cohesive layer, and the other incorporating a cohesive layer at the adhesive’s mid-plane while modelling its entire thickness, using both 2D and 3D techniques. Validation was conducted against experimental data from the literature that examined the influence of adhesive thickness on fatigue behaviour in DCB and CLS tests. The findings of this study confirm that the model accurately predicts fatigue disbonding across all cases examined. Additionally, the analysis reveals that modelling adhesive thickness plays a critical role in the simulation’s outcomes. Variations in adhesive thickness can significantly alter the crack growth behaviour, highlighting the importance of carefully considering this parameter in future assessments and applications. Full article

Underground granaries naturally preserve grain quality by maintaining low temperatures and reduced oxygen levels, eliminating the need for artificial cooling and pest control. However, cast-in-place reinforced concrete construction faces challenges such as waterproofing and complex on-site processes, necessitating prefabricated steel plate-concrete composite structures with robust joints for enhanced structural integrity and streamlined construction. The study utilizes a full-scale prefabricated steel plate-concrete underground silo, instrumented with strain gauges on circumferential steel bars and internal steel plates to monitor stress variations during six distinct backfilling loading cases. Concurrently, finite element models were developed using ABAQUS 6.14 software for numerical simulations, which were validated against experimental data. Stability analyses, including buckling load assessments and parameter sensitivity studies, were conducted to evaluate the effects of joint quantity and bending stiffness on the structural performance of the composite walls. The results revealed that circumferential joints play a critical role in stress distribution within the composite walls, underscoring the necessity of optimized joint design. The numerical model accurately replicated experimental results, with deviations below 9%, confirming its reliability. Furthermore, an equivalent joint design method was established, demonstrating that a joint bending stiffness ratio above 1.1 ensures that prefabricated composite walls achieve critical buckling loads comparable to cast-in-place walls. These findings provide a robust framework for enhancing the structural performance and reliability of prefabricated underground silos. Full article

This paper presents detailed numerical modeling of externally prestressed concrete (EPC) beams with fiber-reinforced polymer (FRP) rebars. Particular attention is paid to the bond–slip interactions between FRP rebars and concrete. A refined 3D finite element model (FEM) incorporating a script describing the bond–slip of FRP rebars and concrete is developed in ABAQUS. The model effectiveness, rooted in the interface behavior between FRP rebars and concrete, is comprehensively assessed using experimental data. A comprehensive investigation has been conducted using FEM on the mechanical behavior of carbon fiber-reinforced polymer (CFRP) tendon–EPC beams with FRP rebars. Due to the bond–slip effect, FRP rebars in EPC beams exhibit a distinct phenomenon of stress degradation. This suggests that the traditional method based on plane cross-sectional assumptions is no longer suitable for the engineering design of EPC beams with FRP rebars. Moreover, the study assesses several models including typical design codes for their accuracy in predicting the elevation of ultimate stress in external tendons. It is demonstrated that some of the design codes are overly conservative when estimating the tendon stress in EPC beams with FRP rebars. Full article

Reactive powder concrete (RPC) is widely used in ultra-high-rise buildings, hydropower stations, bridges, and other important infrastructures. To study the dynamic response and damage characteristics of RPC columns and frames considering coupled fire and explosions, an analytical model of RPC columns and frames with coupled fire and explosions was established by using ABAQUS (2021) finite element software. The dynamic response and damage degree of RPC columns under coupled fire and explosions were investigated to reveal the influence laws of parameters such as cross-section size, axial compression ratio, reinforcement rate, and fire duration on the dynamic response of RPC columns at high temperatures. The dynamic response of the frame structure was analyzed when the explosion load was applied to the bottom corner columns, side columns, and top beams, respectively. The results show that the fire severely weakened the blast resistance of RPC columns; the maximum mid-span deformation and residual deformation of RPC columns decreased with the increase in cross-section size and longitudinal bar reinforcement ratio and increased with the increase in fire duration and axial compression ratio. When the explosion load was applied to the corner columns of the bottom floor of the frame, the bottom corner columns were almost completely destroyed, and there was a significant risk of the structure collapsing. Based on the results of the data analysis, a method to enhance the explosion resistance of RC frame structures using RPC materials at high temperatures is proposed. Full article

Since fan blades are exposed to fatigue, and in some cases harsh loading conditions, they may exhibit fracture failures due to crack propagation, resulting in significant losses. Previous studies of crack propagation in blades are mainly confined to either simplified blade geometry or loads, resulting in a significant discrepancy between the simulated crack propagation and the real blade propagation behavior, while it is lacking for challenging shapes and loads. A co-simulation approach of FRANC3D and ABAQUS was developed to study the crack propagation of an axial-flow fan blade subjected to centrifugal, aerodynamic, and combined loads. The projected approach is validated with results obtained from analytical calculations and experiments. Meanwhile, making use of benchmarks, the Stress Intensity Factor (SIF) and the prediction of mixed-mode crack growth path are validated. Considering various loads, the crack propagation path response for the fan blade is computed for different growth steps. The results pinpoint that the crack propagation length of the crack tip center is maximum under centrifugal loading. However, the aerodynamic load led to a maximum propagation length of the crack tip endpoints. In addition, the combined force of centrifugal and aerodynamic loads limits the crack from growing. Full article