Engineering and Technology Journal Vol. 36, Part A, No.

3, 2018

Manal H. Jasem Studying of Buckling Behavior on Composite

Mechanical .Eng. Dep.
AL-Mustansiriya
Material
University, Baghdad, Iraq
Abstract- In this paper the buckling behavior of composite specimen manufactured
Awatif M. Ali from polyester reinforced with fiberglass, jute fiber and eggshell powder were
Mechanical .Eng. Dep. studied. Several samples with rectangular cross section area of (1.5*19) mm are
AL-Mustansiriya prepared with length of (400, 500, and600) mm and with addition weight ratio of
University, Baghdad, Iraq (5%) of different material for reinforcement, used for tensile and buckling test.
Awatif_alimustafa@.com Different types of natural and synthetic materials (matrix and random glass fibers
(are used first without any addition then with adding (5% SiC or 5% Eggshell
powder or 5% ) to the matrix, and Jute fibers. The critical load for its best
results was to the random016 fiberglass without addition but its worst results were
Received on: 04/05/2016 with jute addition. The results of other additions (SiC, Egg shell powder,
Accepted on: 29/09/2016
and matrix without addition was in between. The experimental with theoretical
results has been calculate and then compared

Keywords- buckling of columns, buckling of composite material.

How to cite this article: M.S. Jasim and A.M. Ali,“Studying of Buckling Behavior on Composite Material” Engineering and Technology
Journal, Vol. 36, Part A, No. 3, pp. 233-233, 2018.

1. Introduction 2. Literature Review

Composite materials are extensively used in naval Lee et al. studied the buckling behavior of
industry airframe structures, storage tanks, orthotropic square plate, either with or without a
petroleum pipes, cars, and high- tech designs, central circular hole. Results showed that the
because of their high strength to weight ratios. So existence of central circular holes might cause a
it is very useful to predict their degradation higher buckling strength than the plates without
service loads and environment [1].As well as it holes. [2]. Oleiwi et al studied the buckling
used in many fields of engineering like buildings, analysis of composite specimen reinforced with
bridges, boat hulls, swimming pool panels, race two types of glass fibers (fine and coarse woven
car bodies, shower stalls, bathtubs and storage fibers). In addition, make mathematical models
tanks. In addition to that, industries where weight by using statistical analysis, which shows the
reduction is of prime concern (aviation etc.). critical load of the composite specimen as a
Composites are capable enough to take different function of volume fraction, fiber angle and
types of loading both tensile and compressive aspect ratio [3]. Al Qblan studied the effect of
based on the requirement [8].In many engineering various parameters on the buckling load of square
structures such as columns, beams, or plates, their cross-ply fiber-glass laminated plates with
failure develops not only from excessive stresses circular cutouts. (Size, cutout location, fiber
but also from buckling. The magnitude of the orientation angle and type of loading) Three types
compressive load at which the plate becomes of loading were considered; uniaxial, biaxial
unstable is called the “critical buckling load.” the compression and shear loading. The results of
mechanical properties can be varied as required buckling load are compared to theoretical and
by suitably orienting the fibers. Development of numerical values [4]
new applications and new composites is Kumar studied the influence of cut-out shape,
accelerating due to the requirement of materials length/thickness ratio, and ply orientation and
with unusual combination of properties that aspect ratio on the buckling of woven glass epoxy
cannot be met by conventional monolithic laminated composite plate is examined
materials. Actually, composite materials are experimentally. Clamped–free -Clamped-free
capable of covering this requirement in all means boundary condition is considered for all case.
because of their heterogeneous nature. Properties Experiments have been carried out on laminated
of composite arise as a function of its constituent composites with circular, square and rectangular
materials, their distribution and the interaction cut-outs. The thickness of the plate was changed
among them and as a result, an unusual by increasing the number of layers. After the
combination of material properties can be buckling experiments, micro electroscopic
obtained [4]. scanning was performed for the failed specimens.
https://doi.org/10.30684/etj.36.3A.11
2412-0758/University of Technology-Iraq, Baghdad, Iraq
This is an open access article under the CC BY 4.0 license http://creativecommons.org/licenses/by/4.0
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Comparisons are made between the test results, E: Modulus of elasticity (Gpa)
by using two different approaches. The results
shows effect of various cut-out shapes, 3. Materials and Experimental Procedure
orientation of fiber, aspect ratio and length to The critical load of composite material was
thickness ratio on the buckling load (All measured for the following cases:-
specimen were loaded slowly until buckling) [5]. 1-Different types of reinforcement fiberglass
Ganesan et al. studied the presence of holes (Random, mat), jute, and Eggshell (SIC,
redistributes the membrane (E-glass woven
as powder with polyester as the matrix were used
roving with polyester resin.) stresses in the plates
the volume fraction is 30% for all types.
and may reduce their stability significantly. The
2-Three type of fixation were used, such as
buckling of such perforated plates deal with the
(Fixed-fixed end, Pin -fixed end, Pin-pin end)
buckling analysis of symmetrically and laminated
3-Three type of length (400,500,600 mm) were
composite plates under two sides simply
used The Materials Used:
supported and two sides free boundary condition.
The hardener used is (Methyl Ethyl Keton
The effects on buckling load by various cut out
Peroxide “MEKP”)
shapes (circular, squared elliptical) and sizes are
investigated. It was observed that the plate with
Table 1: The properties for epoxy (Sikadur-300)
the circular cutout yielded the greatest critical
buckling load when compared with the square Properties Unit Q
and elliptical cutouts [6]. Density Kg\ 1.3
Oleiwi estimated the critical load of Tensile strength MPa 30
unidirectional polymer matrix composite plate by
E-modulus GPa 3800
using experimental and finite element techniques
at different fiber angles and fiber volume fraction
from glass fiber reinforced unsaturated polyester). Table (2) the properties for E-glass [Hull 1981]
The composite specimens were prepared by hand Properties Unit E-Glass
lay-up technique with different fiber volume Density Kg\ 2.5
fraction Vf, aspect ratio and angle of The results Tensile strength GPa 1.4-2.5(typical)
illustrated the critical load decreases in nonlinear E-modulus GPa 76
relationship with the increases of the fiber angle
and that it increases with the increases of the fiber I. Specimen’s preparation
volume fraction [7]. The specimens used, are prepared in the
Parth Bhavsar buckling behavior of glass fiber workshop laboratory, University of Al-
reinforced polymer subjected to linearly varying Mustansiriya by hand-Lay-up moulding, using an
loading has been studied by finite element open glass mould with dimensions (65cm*50cm).
method effects of varios parameters on the before pouring begins ,mould sides and surface
buckling load of rectangular plates with aspect treated chemically with paraffin for the purpose
ratios1 have been investigated [8]. of closing the spaces and take out the sample
The aim of this research was to study the easily ,putting plastic sheet, fixed fiber glass
influence of addition (5%) from (SiC,〖AL〗 ,(epoxy and hardener) deposited on the mould by
_(2O_3 ) egg shell) and increase of the length on brush ,any air which may be entrapped was
critical load to synthetic and natural composite removed using serrated steel roller, again plastic
column made from of unsaturated polyester sheet cover mold upper part by applying poly
reinforced by( matrix and random glass- vinyle alcohol inside the sheet as releasing agent.
fibers)and jute fiber as natural fiber . Then heavy flat metal rigid platform was kept top
of plate for compressing purpose. Left for (48hr)
Theory before being transported to cut to exact shape for
Column fails by buckling when the axial testing.
compressive load exceeds some critical load. The In this study, three different plate lengths were
critical load of the composite column can be used: 400mm, 500mm and600mm. The width
calculated from the Euler equation as follows [7] (19mm) and thickness of the plates are (1.5mm).
(1) II. Experimental apparatus
Where-:
The buckling testing apparatus used in this work
C: is the end condition number ,
(in University of Al-Mstansiriya, Mechanical
L; is the length of the column (m)
department) is shown in Figure 1.
I: is the moment of inertia (m^4)

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Figure 3: samples of tensile test at ASTM-D638

Figure 1: the test apparatus [Experimental work P39]

III. Tensile test 4. Results and Discussion

The specimens were loaded in axial tension using Young modulus
an Instron tensile testing machine of 100 KN The values of young’s modulus show the
capacities. The specimen was clamped at two ends. highest value for random glass-fiber
Applied load until they were failed compration with other used material this
is due to random orientation for fiber
which form zero angle as well as the
transverse fiber plays secondary role in
resistance and it is function to reduce
deflection in the matrix material in the
other hand the specimens with addition
come in the second place then matrix
glass-fiber. The Young’s Modulus is
calculated experimentally and the result is
shown in Table 3.
Figure 2: Standard Dimension Specimen

Table 3: Young’s modulus

Specimen Young Modulus MPa Moment of inertia
Mat (glass fiber+polyester) 2616.6 5.34375
Random( glass fiber+polyester) 7880 5.34375
Jute fiber+polyester 1918.27 5.34375
5%Eggshell(glassfiber+polyester) 2948 5.34375
5%SiC(Mat glassfiber+polyester) 2812.5 5.34375
5% (Matglassfiber+polyester) 4116.6 5.34375

Critical load: - Sample of calculation (critical Pcr=

load):-
1-for pin ended:- Pcr= =2.2N
Pcr= 3-for pin fixed ended

Pcr= =0.86N Pcr=

2-for fixed ended:- Pcr= =0.76N

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Buckling (critical load) of composite material is addition except (with jute) give better results and
investigated when discuss the effect of the type of this is can be seen clearly at fig(4-6).
fixture it can be seen that the maximum critical All theoretical charts figs (7-9) the highest value
load occurs with Fixed-fixed ended for all cases. was to the random fiber-glass (with or without
From figures.4, 5, 6 it can be clearly seen that the addition) and this is because of the randomly
egg shell composite sustain higher load while the distributed fibers that cause distribution in stress
jute fiber composite sustains lower load this so increases the resistance of material to
means that the egg shell powder which contains withstand the external force. , while with addition
( is stiffer than jute-fiber the best material is due to it is good
According to the effect of the length, there is properties when compared with others [9]
increase in critical load with addition at a ratio of( Experimental figures differ when compared with
6.5% for SiC,11% for Egg-shell and 13%for theoretical one while using the same (length and
at a length of (400mm) and fixed end fixation method) this is due to method of
method, while reinforce with jute gives decrease preparing the sample (hand lay-up) and
(26%)when it compared with sample (matrix homogenous in properties over all the samples.
glass-fiber and without addition).At
length(500mm)without addition was the best Charts
while At length of (600mm) the samples with Expermental chart

Fixed-fixed end expermental

8

6 Mat
Random
Critical Load N

4 Jute
5% Egg-shell
2
5% SiC
0 5% AL2O3
400 450 500 550 600
Lenght mm
Figure 4: relation between the critical load and the length (Fixed ended)

Pin -Fixed end Expermental

5
Critical Load N

4 Mat
3 Random
2 Jute
1 5% Egg-shell

0 5% SiC
400 450 500 550 600 5% AL2O3
Lenght mm

Figure 5: relation between the critical load and the length (Pin fixed)

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Engineering and Technology Journal Vol. 36, Part A, No. 3, 2018

2.5 Pin-ended expermental

2 Mat

Critical Load N 1.5

Random
Jute
1 5% Egg-shell

0.5 5% SiC
5% AL203
0
400 450 500 550 600
Lenght mm
Figure 6: relation between the critical load and the length (Pin ended)
Theoretical chart

Pin ended theoretical

3
Mat-fiber
2.5 glass
Crtical Load N

Randim
2

1.5 Jute

1 5%Egg-shell

0.5 5%SIC
0
400 450 500 550 600 650
Lenght mm

Figure 7: relation between the critical load and the length (Pin ended)

Fixed ended theoretical

12

10
Mat
Critical Load N

8 Randim
6 Jute

4 5%Egg-shell
5% SIC
2
5% AL2O3
0
400 450 500 550 600 650
Lenght mm
Figure 8: relation between the critical load and the length (Fixed ended)

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Engineering and Technology Journal Vol. 36, Part A, No. 3, 2018

Pin-Fixed theoretical
6

5
Critical Load N Mat
4
Randim
3
Jute
2
5% Egg-shell
1
5% SIC
0 5% AL203
400 450 500 550 600 650
Lenght mm

Figure 9: relation between the critical load and the length (Pin fixed)

5. Conclusion Cut-out Subjected to In-Plane Shear,” Jordan Journal,

Vol. 3, No. 2, 184, 2009.
1. Failure modes of composite column depend on
the type of loading, constituent material, [5] R.A. Kumar “Buckling Analysis of Woven Glass
epoxy Laminated Composite Plate,” MSC Thesis
properties and geometrical dimensions.
India, 2009.
2. It was noted that different length affected at
critical buckling load. Buckling load decreases as [6] C. Ganesan and P.K. Dash “Elasto Buckling
Behaviour of Gfrp Laminated Plate with Central
the length increases. The rate of decrease of
Holes,” International Journal of Mechanical &
buckling load is not uniform with the rate of Industrial Engineering India, Vol. 1, No. 1, 2011.
increase length [8].
[7] J.K. Oleiwi, E.S. Al-hassani and A.A. Mohammed,
3- There is a difference between experimental and
“Modeling and buckling Analysis of Polymeric
theoretical results, and this is due to: method of Composite Columns,” Eng. and Tech. Journal, Vol.
preparing the samples and homogenous in 32, Part A, No.5, 2014.
properties over all the samples.
[8] Buckling Analysis of Laminated Composite Plates,
4- It can be noticed that addition of ( , SiC, Thesis Submitted In Partial Fulfilment of the
egg-shell) to the samples lead to uniform slop Requirements for the Degree of Bachelor of
whereas without addition suffering sharp tangent Technology in Mechanical Engineering,
slop. [9] “Fundamentals of Modern Manufacturing” Mikell
5- The critical load values decreased for all P. Groover printed in United States of America
prepared samples with addition while it’s higher
without any addition due to the alteration in
metal stiffness, which is an indicator of Young’s
modulus that can vary somewhat due to
differences in sample composition and test
method

References
[1] R. Jones “Mechanics of composite materials,”
Second edition 1990.
[2] Y.J. Lee, Lin H.J. and Lin C.C. “A study on the
buckling behavior of an orthotropic Square plate with
a central circular hole" J composite structures, Vol. 13,
No. 173, 188, 1989.
[3] J.K. Oleiwi, “Buckling Analysis of unidirectional
Polymer Matrix Composite Plates,” AL-Khwarizmi
Engineering Journal, Vol. 2, No. 2, 2006.
[4] H. Al Qablan, “Assessment of the Buckling
Behaviour of Square Composite Plates with Circular

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