CHAPTER 2 LITERATURE REVIEW - INFLIBNETshodhganga.inflibnet.ac.in/bitstream/10603/12398/8/09...17...
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CHAPTER 2
LITERATURE REVIEW
2.1 LITERATURE SURVEY RELATED TO PRESENT WORK 17
2.2 SUMMARY OF LITERATURE REVIEW AND GAPS FOUND
TO ESTABLISH PRESENT WORK 38
BIBLIOGRAPHY 39
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CHAPTER 2
LITERATURE REVIEW
The evolution of composite material has replaced most of the conventional
material of construction in automobile, aviation industry etc. Fibre reinforced
composites have been widely successful in hundreds of applications where there was
a need for high strength materials. There are thousands of custom formulations which
offer FRPs a wide variety of tensile and flexural strengths. When compared with
traditional materials such as metals, the combination of high strength and lower
weight has made FRP an extremely popular choice for improving a product’s design
and performance.
2.1 Literature Survey Related to Present Work
Polymer matrix composites are predominantly used for the aerospace industry,
but the decreasing price of carbon Fibres is widening the applications of these
composites to include the automobile, marine, sports, biomedical, construction, and
other industries [1]. Carbon Fibre polymer-matrix composites have started to be used
in automobiles mainly for saving weight for fuel economy. The so-called graphite car
employs carbon Fibre epoxy-matrix composites for body panels, structural members,
bumpers, wheels, drive shaft, engine components, and suspension systems. This car is
570 kg lighter than an equivalent vehicle made of steel. It weighs only 1250 kg
instead of the conventional 1800 kg for the average American car. Thermoplastic
composites with PEEK and polycarbonate (PC) matrices are finding use as spring
elements for car suspension systems [2]. An investigation was conducted by Issac M
Daniel et.al [3] on failure modes and criteria for their occurrence in composite
columns and beams. They found that the initiation of the various failure modes
depends on the material properties, geometric dimensions and type of loading. They
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reported that the loading type or condition determines the state of stress throughout
the composite structure, which controls the location and mode of failure. The
appropriate failure criteria at any point of the structure account for the biaxiality or
triaxiality of the state of stress. Jeam Marc et.al [4] investigates the modeling of the
flexural behavior of all-thermoplastic composite structures with improved aesthetic
properties, manufactured by isothermal compression moulding. A four noded plate
element based on a refined higher order shear deformation theory is developed by
Topdar et.al [5] for the analysis of composite plates. This plate theory satisfies the
conditions of inter-laminar shear stress continuity and stress free top and bottom
surfaces of the plate. Moreover, the number of independent unknowns is the same as
that in the first order shear deformation theory. Banerji and Nirmal [6] reported an
increase in flexural strength of unidirectional carbon Fibre/ Poly(methyl
methacrylate), composite laminates having polyethylene Fibres plies at the lower face
Li and Xian [7] showed that the incorporation of a moderate amount of carbon Fibres
into ultra-high-modulus polyethylene (UHMPE) Fibres reinforced composites greatly
improved the compressive strength, flexural modulus while the addition of a small
amount of UHMPE Fibres into a carbon Fibre reinforced composite remarkably
enhanced the ductility with only a small decrease in compressive strength. Rohchoon
and Jang[8] studied the effect of stacking sequence on the flexural properties and
flexural failure modes of aramid-UHMPE hybrid composites. The flexural strength
depends upon the type of Fibres at the compressive face and dispersion extent of the
Fibres. Matteson and Crane [9] reported increase in flexural strength by using
unidirectional steel wire tapes in glass Fibre composites and carbon Fibres
composites. They showed that the increase in flexural strength was due to a change in
failure mode from compressive buckling to nearly ductile tensile failure. Bradley and
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Harris [10] used unidirectional high carbon steel wires to improve the impact
properties of epoxy resin reinforced with unidirectional carbon Fibre reinforced.
Unfortunately, flexural design methodologies rely on their experimental
boundary conditions and the particular laminate setup, since a scaling of the results is
very difficult. The occurrence of usual failure modes under flexural loading
conditions, like delamination, matrix tensile fracture, localized compressive failure
and Fibre shear failure is strongly dependent of the material configuration (Fibre type,
resin type, lay-up, and thickness), the loading type. In this respect, three point bend
test equipment along with specimen indicated in figure 1 was used as a fast and cost
efficient comparison tool.
Jawad Kadhim Uleiwi [11]: Studies Investigated the effect of fibre volume fraction
on the flexural properties of the laminated composite constructed of different layers,
one of them having reinforced glass fibre and the other layer reinforced with Kevlar
fibre has been investigated experimentally and the results illustrate that tension stress
decreases with the increase in fibre volume fraction of glass fibre of the lower layer
while it increases with the increase of Kevlar volume fraction of the upper layer.
Wen-Pin Lin et.al [12]: Studies analysed the Failure of Fibre-Reinforced Composite
Laminates under Biaxial Tensile Loading. With the onset of failure for individual
lamina is determined by a mixed failure criterion composed of the maximum stress
criteria. It was observed that after the initial damage takes place, the response of the
lamina was described and observed to be brittle or degrading modes with the collapse
of the entire laminate.
Amjad J. Aref et.al [13]: Examined the structural behaviour of the fibre reinforced
polymer-concrete hybrid bridge superstructure system subjected to negative moment
flexural loads through experimental procedures. The experimental results showed that
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the design of the hybrid FRP-concrete bridge superstructure under a negative flexural
moment is found to be stiffness- driven instead of strength-driven.
Slimane Metiche and Radhouane Masmoudi [14]:Studied the flexural behaviour of
light weight fibre reinforced polymer (FRP) poles. Experimental results show that the
use of low linear density glass-Fibres could provide an increase of the ultimate load
carrying capacity up to 38 % for some fibre reinforced polymer poles. It is also
observed that , the positioning of the hole in the compression side compared to the
tension side leads to an increase of the ultimate load carrying capacity up to 22 % for
the 5.4m (18 feet) fibre reinforced polymer poles and it was learnt that there was no
significant effect (3,5%) for the 12m (40 feet) fibre reinforced polymer poles. This is
mainly due to the stacking sequence and the stress states generated around the hole.
H. A. Rijsdijk et.al [15]: Investigated the influence of maleic-anhydride-modified
polypropylene (m-PP) on monotonic mechanical properties of continuous-glass-fibre-
reinforced polypropylene (PP) composites. This study showed an increase in
composite strength as a result of the addition of maleic-anhydride- modified PP to
continuous-glass-fibre-reinforced PP composites. An optimum in both longitudinal
and transverse flexural strength was reached for composites based on a PP matrix
with 10wt% m-PP.
P.N.B. Reis et.al [16]: Studied the flexural behaviour of hand manufactured hybrid
laminated composites with a hemp natural fibre/polypropylene core and two glass
fibres/polypropylene surface layers at each side of the specimen. Laminate composites
(LC) present an ultimate strength about 4% higher than the hybrid laminated
composites (HLC) associated to changes in failure mechanisms, while the stiffness
modulus was also about 3.8% higher. Fatigue strength of hybrid laminated composites
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is also about 20% lower than the laminated composites as consequence of the change
of the failure mechanisms and of the different static strengths.
M. Davallo et.al [17]: Investigated the Mechanical behaviour of unidirectional glass-
polyester composites to identify performance differences of composites with different
glass lay-ups and laminate thicknesses during flexure and tensile testing formed by
hand lay-up moulding (HLU). es. The damage generated in the composites exhibited
matrix cracking on the lower face followed by the coalescence of delaminations
formed within the reinforcing plies.
Michel Espinosa Klymus et.al [18]: Evaluated the fracture pattern of four
composites for indirect dental restoration relating to three-point flexural strength.
Further the compressive strength and modulus of elasticity were also addressed.
Composites polymerized under high temperatures (belle Glass and Targis) had higher
flexural strength and elastic modulus values than composites polymerized by light
temperatures (Artglass and Solidex). It was found that they failed earlier under
compression because they were more rigid and showed partial fracture in the material
bulk.
S. Benjamin Lazarus et.al [19]: Investigated the mechanical properties of natural
Fibre developed using a plant fibre which is used for green manuring called Sunhemp.
Polyester is used as the matrix to prepare the composite. From the results the
applications of the composite for some specific purposes can be decided upon since
the maximum value of strength is achieved for a particular Fibre length and Fibre
weight ratio.
M. Wesolowski et.al [20]: Studied the elastic properties of laminated composites by
different Non-Destructive techniques. Two carbon fibre XP45 Turane Resin
laminated composite plates and four beams cut from the plates along their principal
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directions 1, 2 (two beams from each plate), are chosen for the study. Among all
proposed methods for the elastic properties characterization, the approach based on
the inverse technique is most suited for the convenient, fast, and accurate
identification of elastic properties.
J. Davies and H. Hamada [21]: Investigated the flexural properties of hybrid
unidirectional fibre reinforced polymer (FRP) composites containing a mixture of
carbon (C) and silicon carbide (SiC) fibres were evaluated at span to depth (S/d) ratios
of 16, 32, and 64. The hybrid composite flexural strength was generally higher than
either the pure CFRP or SiC fibre composites. The work of fracture was a factor of
2.6 larger for the S 4 /C 4 specimen compared to the S specimen and suggests that
these hybrid FRP composites may have a role as energy absorption materials. The
compressive stress, compressive strain and modulus to failure of the SiC fibre were
estimated to be 3.46 GPa, 157 GPa, and 0.018, respectively. Most of the specimens
exhibited out-of-plane pairs of conjugate kinks although specimens with larger SiC
fibre were more inclined to show evidence of shear failure.
IH Tacir et.al [22]: Studied the reinforcing effect of glass fibres on the fracture
resistance and flexural strength of acrylic resins. In this study, statistically significant
differences were found in the flexural strength of the specimens. The injection-
moulded, fibre reinforced polymers had significantly lower flexural strength than the
injection-moulded composites, and the microwave-moulded, fibre reinforced
composites had lower flexural strength than the microwave-moulded composites. The
fracture resistance was significantly higher in the injection moulded, fibre-reinforced
composites than in the injection-moulded composites, and the fracture resistance was
significantly higher in the microwave moulded, fibre-reinforced composites, than in
the microwave-moulded composites.
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Hoo Tien Kuan et.al [23]: Evaluated the mechanical properties of composite
materials based on two types of self-reinforced polypropylene (SRPP) and a glass
fibre reinforced polypropylene are investigated under quasi-static and dynamic
loading conditions. Hybrid laminates based on glass fibre reinforced polypropylene
skins and a self-reinforced polypropylene core was manufactured using a
compression moulding technique. Hybridising the glass and polypropylene fibre
composites in this manner combines the strength and stiffness of the glass fibres
system with the excellent impact resistance and low density of the self-reinforced
polypropylene composite. Tests have shown that increasing the volume fraction of
self-reinforced polypropylene can enhance the energy-absorbing characteristics of the
hybrid composites. Further with the increase in the amount of glass fibre in the
reinforced composite there was an increase in the flexural modulus of the hybrid
composites.
M. Davallo et.al [24]: Flexural properties of continuous random glass-polyester
composites formed by resin transfer moulding (RTM) and hand-lay up (HLU)
moulding have been studied to determine the effects of glass content, composite
thickness, reinforcement geometry and type of fabrication on damage developed
during flexure tests. Strain values both at maximum-load and failure were determined.
The failure strains of the two sets of composite series were relatively constant. Hence,
both types of composite series appeared to fail at a critical strain value. The damage
developed during the test was monitored on the side of each polished beam using an
optical microscope.
S. Tolson and N. Zasara [25]: Investigated the computational model for determining
the ultimate strength of an arbitrary laminated composite plate. A new higher order
shear deformation plate theory was developed. The theory utilizes seven degrees of
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freedom at each node. An improvement in the accuracy of the transverse shear stress
was obtained by calculating these stresses using three-dimensional elasticity
equilibrium equations. The composite failure analysis is used to determine the first
and last ply failure of a laminated composite plate. The computer programming was
developed based on the seven degree of freedom higher order shear deformation plate
theory.
Geon-Woong Lee et.al [26]:Studied the mechanical properties and failure
mechanisms of through-the-thickness stitched plain weave glass fabric/polyurethane
foam/epoxy composites. Hybrid composites were fabricated using resin infusion
process (RIP). Stitched sandwich composite increased drastically the flexural
properties as compared with the unstitched fabrics. Breaking of stitching in yarns was
observed during the flexural test and thus the failure mode yielded relatively high
flexural properties. Polymer composites with stitched sandwich structure improved
the mechanical properties with increasing the number of stitching yarns. It was
concluded from the study that proper combination of stitching density and types of
stitching fibre is important factor for through-the-thickness stitched composite panels.
N.K. Naik et.al [27]: Investigated the inter laminar shear behaviour of typical
polymer matrix composites under high strain rate shear loading. Tensional split
Hopkinson bar (TSHB) apparatus is used for the studies in the shear strain rate range
of 496–1000/ s. It is observed that the interlaminar shear strength at high strain rate is
enhanced compared with that at quasistatic loading. Further, it is observed that the
inter laminar shear strength increases with increasing shear strain rate within the range
of shear strain rate considered.
Slavisa Putic et.al [28]: This paper outlines the experimental investigation of inter
laminar shear strength as the critical mechanical property of composite constructions
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of structure elements Placed between two thin glass mat layers where a layer is placed
on the glass fabric of the same structure but of different density, with different
polyester resin matrices. The significance of the shear strength lies in the fact that for
all types of composites it is strongly influenced by factors weakening the interface
binds.
W.Richards Thissels et.al [29]: The IM6 Fibres 3051/6 epoxy resin showed a 40%
increased in stress –strain slope under compression loading at strain rate of 2000 L/S
than 1×10-3 L/S when the applied load was parallel,450 and normal to the Fibre axis.
The compression test showed that delamination significant failure component. The
applicability of current hole in plate analytical methods to highly anisotropic material
is there questionable. Both hole in a plate analytical methods indicates that GI is about
50% higher than G1.
Jane Maria Faulstich de Paiva [30]: This paper shows a study involving mechanical
(flexural, shear, tensile and compressive tests) and morphological characterizations of
four different laminates based on 2 epoxy resin systems (8552TM and F584TM). The
results show that the F584-epoxy matrix laminates present better mechanical
properties in the tensile and compressive tests than 8552 composites. Further it is
observed that PW laminates for both matrices show better flexural and inter laminar
shear properties.
Roberto J. Cano and Marvin B. Dow [31]: In this study, the unidirectional laminate
strengths and moduli, of notched (open-hole) and un notched specimens in tension
and Compression tests were performed and the properties of quasi isotropic polymer
composite laminates, and compression after impact strengths of five carbon fibre /
toughened matrix composites, IMT/E7T1-2, IMT/X1845, G40-800X/5255-3,
IM7/5255-3, and 1M7/5260, have been evaluated. This investigation found that all
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five materials were stronger and more impact damage tolerant than more brittle
carbon/epoxy composite materials currently used in aircraft structures.
José Ricardo Tarpani [32]: Quasi-static tensile properties of four aeronautical grade
carbon-epoxy polymer composite laminates, in both as-received and pre-fatigued
states, were determined and compared. The materials also displayed a significant
tenacification (toughening) after exposed to cyclic loading, resulting from the
increased stress (the so-called wear-in phenomenon) and/or strain at the maximum
load capacity of the specimens. Two-dimensional woven textile (fabric) pre-forms
fractured catastrophically under identical cyclic loading conditions imposed to the
fibre architecture, hence this prevents their residual properties from being
determined.
Wen, H.W., Reddy, T. Y., Reid, S. R. and Soden, P. D [33]: Conducted
experiments on composite sandwich panels consisting of woven E-glass/polyester
laminates and foam core and also found that there was an increase in the failure load
of the composite sandwich under impact loading when compared to static load
indentation. They attributed the load increase to the enhanced strength and stiffness of
the glass/polyester face sheet and foam core at high strain rates as well as the inertia
of the projectile and composite sandwich. Layered materials and sandwich structures
have diverse and technologically interesting applications. These include the increased
use of composite laminates in aerospace and automotive engineering.
Hutchinson, J.W, Suo Z, Rajapakse, Y.D.S Valenti, M [34,35,36]:The introduction
of layered concrete pavements in civil engineering, the use of thin films and layered
structures in micro-electronic components, and very recently, the introduction of
sandwich structures in a variety of aerospace, naval, automotive engineering
applications. In an entirely different length scale such materials and structures are also
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found in the natural layered rock structure of earth’s crust. The failure characteristics
of layered materials and sandwich structures subjected to static loading have been
investigated extensively in the past years and their dynamic counterparts have
remained elusive.
C.T., Rechak, S, Much & Cantwell, W.J., Morton, [37,38]: Work have been
addressed to identify the evolution of failure modes for different loading regimes, it is
convenient to first classify these modes based on the material constitutions of
layered/reinforced structures. There are two major categories of failure observed in
post-mortem studies. The first major failure category is de cohesion (or cracking)
between bonded layers at an interface. This is often referred to as de lamination in
composite laminates or interfacial de bonding in thin films or sandwich structures. It
is also called inter-layer failure. In general there are two distinct inter-layer failure
modes observed. The first one involves opening-dominated inter-layer cracking or
‘‘de lamination buckling’’
Wu, H.T., Springer, G.S, Lambros, J., Rosakis, A.J et. al, [39,40]: Polymer
laminate composites involves shear-dominated inter-layer cracks or shear de
laminations, and often occurs in layered materials subjected to out-of-plane impact
was observed, present study described the failure modes by conducting a series of
experiments on dynamic de lamination of thick Fibre reinforced composite laminates.
S.M.R. Khalilia, A. Shokuhfar[41]: Effect of some important parameters on low-
velocity impact response of the active thin-Layered/walled hybrid composite plates
embedded with the shape memory alloy (SMA) wires was investigated. shape
memory alloy wires were embedded within the layers of the composite laminate. The
effect of the shape memory alloy wires on contact force, deflection, in-plane strains
and stresses of the structure was analyzed. The first-order shear deformation theory as
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well as the Fourier series method was utilized to solve the governing equations of the
composite plate analytically. Further the interaction between the impactor and the
plate was modeled with the help of two degrees-of-freedom system, consisting of
springs-mass system. The Lambros linearized Hertzian contact model was used in the
impact analysis of the laminated hybrid composite plate. Results indicated that some
of the important geometrical and physical parameters like the shape memory alloy
volume fraction, orientation of composite Fibres, impactor mass, impactor velocity,
and a/h ratioof the specimen that is length-to-thickness ratio of the plate are important
factors affecting the impact process and the design of the structures.
P. H. Bull et.al [42]: An investigation of the response of sandwich structures
subjected to impact velocities of virtually 0 m/s and approximately 1000 m/s was The
higher velocity exceeds both the longitudinal and the transverse wave propagation
velocities of the core material in the sandwich panels. Their objective was to
investigate the possibility to simulate the damage from ballistic impact of sandwich
panels through quasi-static experiments. Residual strength of impacted panels is
analyzed by finite element analysis.
Per Wennhage [43]: A generic model of a railway car body in sandwich design was
weight optimized subject to various constraints. The constraints were global natural
frequency, buckling and wrinkling, and sound reduction constraints. Finite element
model was used for global natural frequency analysis, while sandwich plate theory
was used for local structural analyses. The acoustic environment is an important
factor in vehicle design, and a sandwich construction may have poor ability to
attenuate air-borne sound, i.e., have a low sound reduction index. The sound reduction
index is affected by the dimensions and materials in the sandwich. By careful design,
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the sound reduction can be improved, while maintaining the light weight properties of
the sandwich design.
Kardomateas. [44]: A nonlinear solution method was developed for buckling and
post-buckling of elliptical de laminations under compressive loads. This method
employs a series solution approach in conjunction with the perturbation technique to
solve the laminated plate equations for large deflections. Experiments were performed
on sandwich panels containing delaminated face-sheets (the de laminations were in
between layers of the face-sheet; the face-sheet/core interface did not contain de
laminations). The nonlinear models were able to predict the onset of de lamination
and failure loads in the experiments.
Liang tseng et.al [45]: An integrated sandwich composite adopting 3D woven fabrics
as the core material was experimentally characterized for its effective elastic modulus
as well as its capacity of receiving impact energy. A series of unidirectional tensile
tests as well as impact experiments were conducted for the sandwich composite
fabricated using two different types of reinforced lamina as the face-sheets.
G. Zhou, M. Hill, J. Loughlan [46]: Damage characteristics of composite-skinned
honeycomb sandwich panels in bending (flexural) were investigated, with both
hemispherical (HS) and flat-ended (FE) indenters. The skin thickness of the cross-ply
is varied from 8 plies to 16 plies, whereas the density of the 12.7 mm thick aluminum
honeycomb core varies from 50 to 70 kg/m3. Panels were loaded quasi-statically and
are clamped in 100-mm testing area are subjected to either bending or on a rigid
base.
Whitney, J.M. and Browning, C.E [47]: The effects of varying these parameters on
damage mechanisms are examined through response curves as well as cross sections
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of selected specimens. Short-beam shear tests for determination of the ILS strength
were conducted.
Bernard, M.L. and Lagace, P.A, Williamson, J.E. and Lagace, P.A [48,49]:
showed that the moderate thickness effect on the ILS strength is negligible and in fact
laminates with fewer plies have slightly higher ILS strength than laminates with more
plies.
U. K. Vaidya, C. Ulven, S. Pillay and H. Ricks [50]:Therefore the value obtained
for the 16-ply laminate was taken as a low-bound approximation for the other
laminates. Lagace and coworkers [conducted a series of quasi-static and low-velocity
impact tests on square composite panels as well as wide composite beams with both
aluminum and nomex honeycomb cores with a hemispherical (HS) indenter/
impactor. considered filling of honeycomb type cores with foam to produce sandwich
constructions. The potential benefits of this approach are enhancement of damage
resistance, and ability to process honeycomb type sandwich structures through cost-
effective vacuum assisted resin transfer molding (VARTM). Two cores are
considered, a polyurethane foam for full filling of honeycomb cells, and syntactic
foam for partial filling, in conjunction with carbon–epoxy face sheets. Their impact
response was investigated under low and high velocity impact (LVI and HVI
respectively).
Hiroshi and Isao [51]: Investigated the evolution of damage behavior considering the
moisture (water) absorption effect on the textile structures. Non destructive method,
that is direct visual observation method was adopted to investigate the damage
observation. The materials investigated were plain woven fabric and multi axial
knitted fabric. Carbon Fibre reinforced laminates of plain woven did not exhibit much
lower performance under compression after impact. On the other hand the properties
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of the water absorbed multi- axial knitted fabric properties decreased drastically when
compared with the dry ones. Water absorption did not alter the strength and had no
effect on the compression after impact strength. There were traces of deterioration
caused due to water absorption in both plain woven and multi axial carbon Fibre
reinforced laminates.
Toshio ogasawara and Tet suoka Sai [52]:Investigated the influence of fullerenes
dispersion on the carbon –Fibre reinforced epoxy matrix for its mechanical properties.
The various mechanical properties like flexural test and short beam shear strength
were conducted and it was observed that by dispersing of fullerenes into the matrix
there was an increase in the mechanical properties.The inter laminar fracture
toughness was enhanced by 60%. The small amount of fullerenes will increase the
failure strain of epoxy resin and in turn improves the carbon Fibre reinforced polymer
strength.
F.Elgabbas et.al. [53]: Conducted experimental investigation on the structural
behavior of precast reinforced hallow concrete slabs subjected to flexural loads. For
the analysis externally bonded laminates with near surface mounted are used. Near
surface mounted technique resulted in optimum strength. Near surface mounted
flexural strengthening needs to be carefully designed to avoid shear failure. Pre
mature de bonding was observed because of externally bonded technique.
Kolesnikov et. al,[54]: Investigated the effect of joining structural composites for
aerospace applications. Structural joining enhances the disturbance in the optimized
structure and results in increase in overall weight of the structure and results in
increase in over all weight of the structure. The potential of the light weight
composite materials made of carbon Fibre reinforced polymers are affected because
of these joining and fastening capabilities. The titanium layers are embedded at these
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joints where fastening and bolting is done which resulted in improvement in structural
efficiency. Hence this demonstrates the influence of titanium hybridization with the
carbon Fibre reinforced polymer materials and results shows advantages of this
hybridization.
Alaattin Aktas and Ibrahim uzun[55]: Investigated the influence of sea water on
the woven glass Fibre laminated composites for its strength. The experiments were
carried by varying the edge distance and the pin diameter. The ratio of width and pin
diameter was varied during the experiments. The failure modes were studied for
varied period of immersion and depths.
B. Pradan and S.K.panda[56]: Studied the effect of residual stresses and mechanical
loading on the ply lay up composites. Inter laminar de lamination crack growth
behavior was analyzed in this paper. Finite element analysis has been performed to
understand the inter laminar elliptical de lamination behavior which is mainly due to
the manufacturing defects and the other reasons for this type of de lamination was
analyzed which may be due to symmetric mid plane quasi - isotropic Fibre reinforced
polymer composite layup. Strain energy release rate procedures were employed to
analyze de lamination and crack growth at the inter faces. It was observed that the ply
sequence and orientation plays a important role in this aspects.
J.Lee and C.Soutis[57]: Investigated the influence of thickness on the compressive
behavior of the laminated composites with different stacking sequence with a open
hole at the centre. It was observed that the strength of the specimen with increasing
thickness was increased. Measured failures strength were compared with the predicted
values.
S.Kellaas, J.Morton and P.T.Curtis[58]: Studied the uni axial strength of centre –
notched laminates under hygro thermal environment. The laminates investigated were
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carbon Fibre reinforced epoxy laminates. Dry and wet specimens were tested for
tension and compression strengths in a varying range of temperatures. The fabrication
was done on two kinds of stacking sequences. The diameters of the holes were varied
and tensile and compression strengths measured and damage response was observed.
It was found that the interactions depend on the stacking sequence and notch
geometry.
M.Raghavendra et. al,[59]: Investigated studies on woven glass Fibre reinforced
polymer matrix and determined the tensile strength, compressive strength and in plane
shear strength at room temperatures and at high temperatures and at high
temperatures. The test data is statistically analyzed it was found that the specimens at
higher temperatures showed low strength when compared with the specimens at room
temperature.
Buket Okutan[60]: Conducted experimental studies to determine strength of
mechanically fastened Fibre – reinforced E-glass/epoxy composites. Various
Mechanical properties and strength was determined experimentally. The laminates
manufactured had different orientations of the Fibres. Parametric study was conducted
considering the geometry of the Fibre orientation and failure characteristics for the
pin-loaded Fibre reinforced laminated composites were analyzed. A comparison
between experimental values with finite element modal was carried. It was observed
that the ply orientation and the geometry of the composites are crucial in case of
pinned Fibre reinforced laminated composites.
Adam Quiter[61]: Aerospace structures are often prone to flexural loads, that may
lead to result in serious damage. Hence, for structural integrity, aerospace structures
must be efficient to resist bending. The first use of modern composite materials in
commercial aircrafts was by Airbus in 1983.
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Pegoretti, E. Fabbri, C. Migliaresi, F. Pilati [62]: Flexural loading causes stresses
in the polymer laminated composites that may vary through the thickness. These
flexural stresses are the maximum at the outer surfaces and are minimum (zero) in the
middle at the neutral axis. In the laminates subjected to pure bending, the composite
failure initiates on either the tensile or compressive side depending upon whether the
composite is stronger in compression or tension respectively. The stress in an
individual ply depends upon the stiffness of that ply and its distance from the
laminate’s neutral axis. By including, one or more extra components having relatively
better elastic properties in the laminate can help in improving the flexural properties
of the composite structures. This class of composite materials consisting of more than
two types of constituents is commonly known as a hybrid composite.
G.Kertsis[63]: Hybrid composites having two or more types of reinforcing Fibres in
a polymer matrix can be classified according to the way their constituent Fibres are
mixed such as; sandwich hybrids, interply hybrids, and intermittently mixed hybrid
composites. Interply hybrid composites are gaining attention because hybridization
facilitates the tailoring of mechanical properties according to need by having a
selective amount of extra reinforcement at some selective position in the laminate.
presented a comprehensive review on the properties of hybrid composites. The
relative volume fraction of reinforcing Fibres and their positioning in the hybrid layup
act as the determining factors in the enhancement of flexural properties. Therefore, for
structural laminates under flexural loading, material can be designed for better
flexural properties by investigating the effect of the stacking sequence.
Banerji and Nirmal [64]: In a hybrid composite, the two reinforcing Fibres differ in
their mechanical properties and the interface they make with the matrix it was
observed that there was an increase in flexural strength of unidirectional carbon Fibre/
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Poly(methyl methacrylate), composite laminates having polyethylene Fibres plies at
the lower face.
Li and Xian [65]: Showed that the incorporation of a moderate amount of carbon
Fibres into ultra-high-modulus polyethylene (UHMPE) Fibres reinforced composites
greatly improved the compressive strength, flexural modulus while the addition of a
small amount of UHMPE Fibres into a carbon Fibre reinforced composite remarkably
enhanced the ductility with only a small decrease in compressive strength.
Rohchoon and Jang [66]:studied the effect of stacking sequence on the flexural
properties and flexural failure modes of aramid-UHMPE hybrid composites. The
flexural strength depends upon the type of Fibres at the compressive face and
dispersion extent of the Fibres.
Matteson and Crane [67]: Reported increase in flexural strength by using
unidirectional steel wire tapes in glass Fibre composites and carbon Fibres
composites. They showed that the increase in flexural strength was due to a change in
failure mode from compressive buckling to nearly ductile tensile failure.
Bradley and Harris [68]: Used unidirectional high carbon steel wires to improve the
impact properties of epoxy resin reinforced with unidirectional carbon Fibre
reinforced laminate. By having steel wire on the compression side of the specimen,
the strength of the laminate got enhanced, thus increasing the energy of the fracture,
increased by 200% by elimination of compressive failure mode. The flexural strength
of the hybrid laminate was increased particularly when the wires were placed in the
compression side of the specimen and also as the volume fraction of the wire was
increased.
Zuoguang et.al [69]: Damage characteristics of composite sandwich panels in
bending were investigated with both hemispherical and flat-ended indenters. The
36
thickness of the cross-ply laminate skins varies from 8 to 16 plies. Clamped panels
with a 100-mm testing area are loaded quasi-statically in bending. The effects of
varying these parameters on damage mechanisms were examined through response
curves as well as cross sections of selected specimens.
Issac M Daniel et.al [70]: An investigation was conducted on failure modes and
criteria for their occurrence in composite columns and beams. They found that the
initiation of the various failure modes depends on the material properties, geometric
dimensions and type of loading. They reported that the loading type or condition
determines the state of stress throughout the composite structure, which controls the
mode of failure and its location. The appropriate failure criteria at any point of the
structure account for the bi axiality or tri axiality of the state of stress.
Jean Marc et.al [71]: Investigates the modeling of the flexural behavior of all-
thermoplastic sandwich composite structures with improved aesthetic properties. The
aesthetic thermoplastic sandwich composites exhibit specific features such as thick
multi-layered faces and significant core properties variation due to processing
conditions. Taking into Consideration these specific features, a three-step calculation
methodology, they developed an accurate analytic model. With the help of the
analytical model developed the equivalent shear properties of the core after
manufacturing was predicted and to take into account the influence of the glass veil
layer used to improve the surface quality of the part.
Topdar et.al [72]: A four node plate element based on a refined higher order shear
deformation theory is developed, for the analysis of composite plates. This composite
plate theory satisfies the conditions of inter-laminar shear stress continuity and stress
free top and bottom surfaces of the plate. Further, the number of independent
unknowns is the same as that in the first order shear deformation theory. Numerical
37
examples of composite plates were solved to validate the element & results are
presented.
Mallick P.K [73]: Polymer matrix composites are predominantly used for the
aerospace industry, but the decreasing price of carbon Fibres is widening the
applications of these composites to include the automobile, marine, sports,
biomedical, construction, and other industries.
Gill, R.M [74]: Carbon Fibre polymer-matrix composites have started to be used in
automobiles mainly for saving weight for fuel economy. The so-called graphite car
employs carbon Fibre epoxy-matrix composites for body panels, structural members,
bumpers, wheels, drive shaft, engine components, and suspension systems. This car is
570 kg lighter than an equivalent vehicle made of steel. It weighs only 1250 kg
instead of the conventional 1800 kg for the average American car. Thermoplastic
composites with PEEK and polycarbonate (PC) matrices are finding use as spring
elements for car suspension systems.
Y.C.Shiah et.al [75]: Investigated an integrated sandwich composite adopting 3-D
woven fabrics as the core material & thoroughly studied its elastic modulus. Even
with extensive applications of 3-D woven sandwich composites due to their improved
mechanical properties, there is no suitable theoretical model that has been proposed to
predict the elastic modulus for such composite structures in the open literature so far.
In this work, a theoretical model by means of a micro mechanics approach and the
rule of mixtures is proposed to predict its effective in-plane elastic modulus. To verify
the veracity of their prediction, unidirectional tensile tests were also carried out to
determine the effective elastic modulus. Eventually, their experimental results turn out
to agree with predicted values.
38
2.2 SUMMARY OF LITERATURE REVIEW AND GAPS FOUND TO
ESTABLISH PRESENT WORK:
After exhaustive literature survey and discussion, it is imperative that the use
of polymer laminated composites is an emerging field in all sectors of the industry
specifically in automotive industries because of its benefits of high strength to weight
ratio in order to enhance performance of the vehicle. Evaluation of Flexural and Shear
properties of laminated composites are realised to be important as flexural test and
short beam shear test are considered as real time tests as most of the components are
subjected to bending and shear load.
1. Flexural and Short beam shear properties for plain bi-woven laminates were
not much emphasised for different fibre orientation in the earlier literature.
2. Flexural properties for varying thickness of the specimens were not being
evaluated especially for fibre reinforcement volume between 54-60 % in the
earlier literature.
3. Effect of de-lamination at the interface between the matrix and Fibre
reinforcement under flexural loads is not being addressed.
4. Not much of the work has been done on correlation of experimental results
with FEA results for different fibre fraction and fibre orientation.
So, in the present work, it is intended to focus the Investigation on flexural and
shear properties of the laminated composite materials which is very useful to the
industry and helps design engineers to choose appropriate materials for specific
applications.
39
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