A STUDY ON TENSILE AND COMPRESSIVE STRENGTH OF HYBRID POLYMER COMPOSITE MATERIALS (E GLASS FIBRE-CARBON FIBRE-GRAPHITE PARTICULATE) WITH EPOXY RESIN 5052 BY VARYING ITS THICKNESS

International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 – 6340(Print),
ISSN 0976 – 6359(Online), Volume 6, Issue 4, April (2015), pp. 17-26© IAEME
17
A STUDY ON TENSILE AND COMPRESSIVE STRENGTH
OF HYBRID POLYMER COMPOSITE MATERIALS (E
GLASS FIBRE-CARBON FIBRE-GRAPHITE
PARTICULATE) WITH EPOXY RESIN 5052 BY VARYING
ITS THICKNESS
Dr. M. Nayeem Ahmed1
, Mr. Mohammed Salman Mustafa2
1
Professor and Head, Dept. of Mechanical Engg.
KNSIT College of Engineering, Bangalore-560045, India
2
Assistant Professor, Dept. of Mechanical Engg.
KNSIT College of Engineering, Bangalore-560045, India
ABSTRACT
Hybrid composite Materials have extensive engineering application where strength to weight
ratio, low cost and ease of fabrication are required. Hybrid composites provide combination of
properties such as tensile modulus, compressive strength and impact strength which cannot be
realized in composite materials. In recent times hybrid composites have been established as highly
efficient, high performance structural materials and their use is increasing rapidly. Hybrid
composites are usually used when a combination of properties of different types of fibers have to be
achieved, or when longitudinal as well as lateral mechanical performances are required. The
investigation of the novel applications of hybrid composites has been of deep interest to the
researchers for many years as evident from reports.
This paper presents a review of the mechanical properties of a hybrid composite [carbon
fiber (37%) – E glass fiber (30%) – Graphite particulate (3%) – Epoxy resin LY 5052(30%)].
Keywords: E- Glass-Carbon-Graphite Composite, Optimization of Thickness of Composite,
Strength, Stiffness, Tensile Modulus.
INTERNATIONAL JOURNAL OF MECHANICAL ENGINEERING AND
TECHNOLOGY (IJMET)
ISSN 0976 – 6340 (Print)
ISSN 0976 – 6359 (Online)
Volume 6, Issue 4, April (2015), pp. 17-26
© IAEME: www.iaeme.com/IJMET.asp
Journal Impact Factor (2015): 8.8293 (Calculated by GISI)
www.jifactor.com
IJMET
© I A E M E

18
1. INTRODUCTION
There is a steady increase both in the number of applications being found for fibre reinforced
plastics and, concurrently, in the variety of fibre/resin systems that are available to designers. Some
of these systems are useful, however, only in highly specialized situations where limitations such as
high cost and brittle fracture behaviour are considered secondary to such qualities as low density,
high rigidity and high strength. By mixing two or more types of fibre in a resin to form a hybrid
composite it may be possible to create a material possessing the combined advantages of the
individual components and simultaneously mitigating their less desirable qualities [1]. It should, in
addition, be possible to tailor the properties of such materials to suit specific requirements.
1.1 Hybrid Composites
Hybrid composites contain more than one type of fiber in a single matrix material. In
principle, several different fiber types may be incorporated into a hybrid, but it is more likely that a
combination of only two types of fibers would be most beneficial [2]. They have been developed as
a logical sequel to conventional composites containing one fiber. Hybrid composites have unique
features that can be used to meet various design requirements in a more economical way than
conventional composites. This is because expensive fibers like graphite and boron can be partially
replaced by less expensive fibres such as glass and Kevlar [3].
Some of the specific advantages of hybrid composites over conventional composites include
balanced strength and stiffness, balanced bending and membrane mechanical properties, balanced
thermal distortion stability, reduced weight and/or cost, improved fatigue resistance, reduced notch.
1.2 Case Study
The objective of the research work is to hybridize the carbon fibre (37%)- E glass fibre
(30%)-Graphite Particulate (3%) - Carbon fibre (37%)- Epoxy resin LY5052 (30%) by using Hand
layup technique and Room temperature Vacuum bag molding.
The research work on the above polymer hybrid composites are carried out in order to
achieve optimal strength with cost effectiveness for different applications [4]. Various tests like
tensile, compression are carried out to study the properties of the above hybrid composites.
2. METHODOLOGY
The basic engineering properties of a composite material can be determined by either
experimental stress analysis (testing) or theoretical mechanics (micromechanics). The
micromechanics approach utilizes knowledge of the individual fibre and resin properties, and the
proportionality of fibres to the resin in the lamina. A rule of mixtures approach can best be used to
derive the majority of the composite lamina properties [5]. For example the lamina axial modulus is
derived from:
Ex = EfVf + EmVm
Where: Ef is the fibre modulus of elasticity
Em is the matrix (resin) modulus of Elasticity
Vf is the fibre volume ratio
Vm is the matrix volume ratio
Vf + Vm = 1 with zero voids

19
The fabrication of composite material includes the selection of the required fibre and matrix
material, and collects the appropriate amount of matrix (Resin). (For example, the called-out ratio of
say 70:30, requires a ratio of 70% fibre weight to 30% resin weight).
2.1 Fibre Volume and Weight Ratio Relationship
While the fibre weight ratio is easily determined by simple weighing, the fibre volume ratio
is quite difficult to determine. Typically, an ASTM test method is employed which requires
destruction of a small sample. However, the determination of fibre volume ratio can be derived from
the fibre/resin weight ratio. The approach is as follows:
Data:
Carbon fibre: 204gsm
Kevlar fibre: 200gsm
Glass fibre: 202gsm
Caron fibre thickness: 0.22mm
Kevlar fibre thickness: 0.27mm
Glass fibre thickness: 0.18mm
Table.2.1: Weight calculation for specimen preparation of carbon fibre, E-glass fibre, graphite
particulate with epoxy resin.
composition
Required
Thickness
0f lamina
(mm)
Weight of carbon fibre Weight of glass fibre
Total
weight
of
fabric
(gsm)
Weight
of
matrix=
30% of
total
weight
of
fabric
(gsm)
weight of
graphite
particulate=
3% of total
weight of
fabric
(gsm)
Total
weight
of the
laminate
(gsm)
No of
Layer
Weight
Of
each
layer
(gsm)
Total
Weight
(gsm)
No
of
layer
Weight
Of
each
layer
(gsm)
Total
Weight
(gsm)
Caron fibre
+ E - glass
fibre +
graphite
particulate
+ Epoxy
2 4 204 816 3 202 606 1422 426.6 42.7 1891
3 6 204 1224 5 202 1010 2234 670 67 2971
4 8 204 1632 7 202 1414 3046 913.8 91.4 4051
Table.2.2: Thickness calculation for specimen preparation of carbon fibre, E-glass fibre, graphite
particulate with epoxy resin.
Compositio
n
Required
Thicknes
s
0f lamina
(mm)
Thickness of carbon fibre Thickness of glass fibre
Total
thicknes
s of
fabric
(mm)
Thicknes
s of
matrix=
30% of
total
thickness
of fabric
(mm)
Thickness
of graphite
particulate
=
3% of total
thickness
of fabric
(mm)
Total
thicknes
s of the
laminate
(mm)
No of
Laye
r
thicknes
s of each
layer
(mm)
Total
thicknes
s
(mm)
No
of
laye
r
Thicknes
s of each
layer
(mm)
Total
thicknes
s
(mm)
Caron fibre
+ E - glass
fibre +
graphite
particulate
+ Epoxy
2 4 0.22 0.88 3 0.18 0.54 1.42 0.426 0.0426 2
3 6 0.22 1.32 5 0.18 0.9 2.22 0.666 0.0670 3
4 8 0.22 1.76 7 0.18 1.26 3.02 0.906 0.0906 4

20
Volume ratio plays a crucial role. The engineering designer uses the fibre volume ratio to
derive the lamina properties and thus after lamination, structural properties. But to achieve the
required fibre volume ratio in wet lay-up processes the fabricator requires the fibre (Reinforcement)
weight to resin (Matrix) weight ratio. The expression is dependent on the ratio of the fibre and resin
densities. This relationship clearly identifies the importance of low fibre densities when compared
with the resin density.
3. EXPERIMENTAL PROCEDURE
3.1 Pre-Fabrication
Before the fabrication, the fabrics and matrix (appropriate quantity of resin with its hardener
based on calculations done for the required thickness and reinforcement-matrix ratio to be taken) has
to be kept in oven setting the temperature at 600
C so that the moisture from resin and fabric (if
present) will be removed, then the resin and hardener is mixed together and gently stirred.
3.2 Fabrication
For the fabrication of polymer matrix composite the required fibres (Reinforcement media)
and Epoxy resin (Matrix material) are to be collected then by applying releasing agent on the work
table mount the releasing layer (Teflon sheet) then again apply the releasing agent and place the first
layer of fabric and wet it then apply the next layer and again wet that follow the same procedure for
all remaining layers, the wetting should be done in such a way that the resin should be distributed
equally on the lamina, care should be taken that there should be no starvation or excess of resin on
the lamina. After the last layer again the resin is applied and covered with Teflon sheet and then the
dead weight is applied over the mold. As the mold is ready it is left to reach the gel time of the resin,
as it reaches the gel time, vacuum is applied by covering the mold by vacuum bag, and is left for
some time to get set so as the resin should be spread equally on mold and excess of resin can be
drawn outside. After the vacuum time it is left as it is at room temperature for 24hrs to cure.
Therefore it is also called as Room Temperature Vacuum Bag Molding (RTVBM)[1].
3.3 Post Curing
As the laminate is ready, it has to be subjected to post curing so that all the layers of the
lamina bond together. This can be achieved by keeping the lamina in oven and set the oven to
increase the temperature gradually to 500
C in 15 minutes from room temperature and hold the
temperature for 30 minutes again ramping up to 800
C in next 15 minutes and hold the temperature
for 30 minutes again ramp up to 900
C in 15 minutes and hold for 30 minutes then ramp up to 1200
C
in 30 minutes and hold for 60 minutes then let the oven cool down slowly to room temperature.
4. EXPERIMENTATION
4.1 Tensile Test
Tensile test is done on polymer fibre reinforced composites lamina to determine the tensile
strength on particular orientation of fibre, reinforced in the composite ply. It is very crucible to
determine the tensile strength, because loading in direction of fibre orientation improves the strength
drastically. Therefore, to evaluate the strength of composites ASTM standards are followed.
According to the ASTM D-3039 for tensile test the following dimensions are used for preparation of
specimen.

21
Fig 4.1.1: Tensile test specimen X=2, 3, 4 mm thick
4.2 Universal testing machine
Fig 4.2.1: Universal Testing Machine
Materials Evaluation Laboratory (MEL) is equipped with closed loop computer controlled
servo-hydraulic universal testing machines of 1300 series, Instron make. All the tests were carried
out in a closed loop computer controlled servo-hydraulic test machine. Principle of operation
involves pumping oil at high pressure through hydraulic power pack, to displace an actuator at a
specified rate, through a servo valve.
Fig 4.2.2: Tensile test specimens before and after the test (Carbon fibre - E- Glass fibre –
Graphite particulate - Epoxy resin 5052).

22
4.3 Tensile Test data of hybrid polymer composite laminates of Carbon fibre - E- Glass
Fibre – Graphite particulate - Epoxy resin 5052
Table 4.3.1: Tensile test data of Hybrid Polymer Composite laminates of Carbon fibre, E-glass
fibre and Graphite particulate with Epoxy 5052 for different thickness.
Sample: 01
Graph 4.3.1(a) Graph 4.3.1(b)
Graph 4.3.1(a): Stress v/s Strain relationship of 2 mm thick samples.
Graph 4.3.1(b): Load v/s Displacement relationship of 2 mm thick samples.
Sample: 02
Graph 4.3.2(a): Stress v/s Strain relationship of 3 mm thick samples.
Graph 4.3.2(b): Load v/s Displacement relationship of 3 mm thick samples.
Sample No
Thickness
(mm)
Tensile strength
(N/mm2
)
Yield
stress
(N/mm2
)
Ultimate
Load
(kN)
%
Elongation
Elasticity
Modulus
(N/mm2
)
1 2 456 400.22 26.88 06.68 4494.20
2 3 431.31 305.00 34.93 13.00 6563.41
3 4 408.11 365.05 44.28 10.74 4645.15

23
Sample: 03
Graph 4.3.3(a): Stress v/s Strain relationship of 4 mm thick samples
Graph 4.3.3(b): Load v/s Displacement relationship of 4 mm thick samples
4.4 Compression Test
A fixture is used to align the specimen in the wedge grips and the grips are therefore
tightened. The wedges are inserted into the compression fixture, and if an extensometer is being
used to measure strain, it is attached to the specimen. The specimen is compressed to failure.
Fig 4.4.1.: Compression Test specimen According to ASTM D 1621
The test was conducted on three samples of 2mm, 3mm and 4mm each. The data Obtained
from the mechanical testing was used to calculate the elastic properties and strength of the
laminates. Compression strength, peak load, breaking load were determined. The table shows the
average Compression properties of multiple specimens for each thickness.
4.5 Compression Test data of hybrid polymer composite laminates of Carbon fibre - E-
Glass Fibre – Graphite particulate - Epoxy resin 5052:
Table 4.5.1: Compression Test data for different thickness of Carbon fibre - E-Glass fibre
- Graphite particulate - Epoxy resin 5052 for different thickness.
Sample number
Thickness
(mm)
Compressive load (kN)
Compressive strength
(N/ mm2
)
1 2 2.35 20.08
2 3 7.80 48.30
3 4 19.24 91.40

24
Sample: 01
Graph 4.5.2 (a) Graph 4.5.2 (b)
Graph 4.5.2 (a): Stress v/s Strain relationship of 2 mm thick samples in Compression
Graph 4.5.2 (b): Load v/s Displacement relationship of 2 mm thick samples in Compression.
Sample: 02
Graph 4.5.3 (a) Graph 4.5.3 (b)
Sample: 03
Graph 4.5.4 (a) Graph 4.5.4 (b)
5. RESULTS AND DISCUSSIONS
The investigation is also done to examine the strength on different thickness of plies, where
it is observed that the strength of the thinner plies is high and as the thickness varies, the strength
goes down, this is because of the improper adharance of matrix between the layers resulting in

25
tension within the layers of composites. As the less thicker plies requires less number of layers of
reinforcement, the inter laminar bonding strength will be more, making the composite reacts
uniformly against the tension, where as in thicker sections, because of the multiple (more number of
layers) the bonding strength will not be uniform across the section resulting in improper distribution
of load among the layers of reinforcement tending it to fail.
5.1 Characterization of Hybrid FRP Laminates
The micro structural study shows the failure modes of the different hybrid composites for
different loading conditions.
Fig 5.1.1 Fig 5.1.2
Fig 5.1.1 SEM images of Carbon fibre – E-Glass –Graphite particulate - Epoxy resin 5052 after
conducting tensile test.
From fig 5.1.1 the microstructure of tensile test specimen shows E glass fibres are getting
break by inter laminar tension by peeling itself off, whereas carbon fibres are under tension and
failed under extreme conditions. In this, particulate graphite fills the gap between the fibres thus
strengthening the composite whereas epoxy resin 5052 bonds the reinforcement and offers resistance
to the acting tensile load
Fig 5.1.2 SEM images of Carbon fibre – E-Glass fibre – Graphite particulate - Epoxy resin 5052 after
conducting compression test.
From fig. 5.1.2 it is seen that rich mixture of epoxy resin bonding the fibres, and since the
concentration of resin is more, thus holding/ bonding of the fibres and failure experiences in the
extreme conditions, as the thickness increases, it offers resistance more and more to the compression
loading.
6. CONCLUSION
From the experimentation and results obtained after testing the following conclusion are
drawn.
1. Composite (Carbon fibre + E glass fibre + Graphite particulate with Epoxy resin 5052)
delivers the high tensile strength in comparison. As the tensile strength of carbon fibre is high,
overall tensile strength of the composite will be high, with which the graphite particulate acts as the
fillers which fills the space in between the fabric warps and wefts, in turn results in improving the
resistance to tensile loads. Epoxy resin 5052 has the property to set steadily (setting time is 3 hours)
causing easy penetration of liquid matrix into the reinforcement fibre layers, making the strong inter
laminar bond, which results in enhancement of tensile strength to greater extent.
2. As the composites are fabricated by laminar bonding (layer by layer), sections (thickness) of
plies affects on strength. It is observed that the strength of the thinner plies is high. As the thickness
varies, the strength goes down, this is because of the improper adharance of matrix between the
layers of fibre renforcement, causing inter laminar tension within the composite. As the less thicker
plies requires less number of layers of reinforcement, the inter laminar bonding strength will be

26
high, making the composite to react uniformly against the tension, where as thicker sections requires
multiple/ more number of layers, bonding strength will not be uniform across the section leading
improper distribution of load among the layers of reinforcement resulting in early failure.
3. The compression strength of the composites increases with the increase in thickness of the
ply. Because compressive forces are acting normal to the section hence the loads are uniformly
distributed in the section thus the reinforcement material carries the load, hence the compression
strength increases with the increase in thickness.
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2. Chamis, C. C., Lark, R. F.,”Hybrid composites – State-of-the-art review: Analysis, Design,
Application and Fabrication”, NASA Technical Memorandum, NASA, TM X-73545
3. Chou, Tsu-Wei, Kelly, Anthony, “Mechanical properties of composites.” Annu. Rev. Mater.
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4. Mirbagheri, Jamal, Tajvidi, Mehdi, Ghasemi, Ismaeil, Hermanson, John C., “Prediction of
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0976 – 6359.

A STUDY ON TENSILE AND COMPRESSIVE STRENGTH OF HYBRID POLYMER COMPOSITE MATERIALS (E GLASS FIBRE-CARBON FIBRE-GRAPHITE PARTICULATE) WITH EPOXY RESIN 5052 BY VARYING ITS THICKNESS

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A STUDY ON TENSILE AND COMPRESSIVE STRENGTH OF HYBRID POLYMER COMPOSITE MATERIALS (E GLASS FIBRE-CARBON FIBRE-GRAPHITE PARTICULATE) WITH EPOXY RESIN 5052 BY VARYING ITS THICKNESS