impact damage on fibre-reinforced.pdf

7/25/2019 Impact damage on fibre-reinforced.pdf

1/16

JOURNAL OF

C O MP O S I TE

MATER IALSArticle

Impact damage on fibre-reinforcedpolymer matrix composite A review

Sandeep Agrawal1, Kalyan Kumar Singh2 and PK Sarkar2

Abstract

As the application of fibre-reinforced polymer composite material continue to increase day by day, so the knowledgeabout the impact behaviour of fibre-reinforced polymer composite structures in the areas such as automotive andaerospace is very much needed. This article attempts a comprehensive review of recent literature in the broaderarea of impact damage. Testing methods and standard parameters as well as discussion of important aspects such asimpactor shape, weight of impactor, velocity of impact, environment in which impact takes place are presented.Furthermore, the damage area, energy absorbed, contact time and many other considerations are discussed. Finally,an effort is made to review the research work by considering all aspects related to impact on such type of compositematerials.

Keywords

Composites, fibre-reinforced polymer, impact damage

Introduction

In present days fibre-reinforced composite materials are

widely used in various engineering applications includ-ing automotive, aviation and engineering structures due

to their lightweight, high stiffness, strength and damp-

ing properties. Air vehicles may be subjected to impact

loads by foreign objects such as debris from runways,

bird strikes or hailstones (during flight). The impact

damage in composite materials may not be detected

sometimes by visual inspection. Such impact-induced

damages occur inside the material and increase after

the onset of small delaminations. In an impact event,

several damage types occur in composite materials such

as matrix cracking, delamination and fibre breakage.

Consequently, the impact behaviour of the laminated

composite materials is an important phenomenon to be

studied.1 The brittle nature of most fibre-reinforced

polymer (FRP) composites accompanying other forms

of energy absorption mechanisms such as fibre break-

age, matrix cracking, debonding at the fibrematrix

interface and especially plies delamination, play

important roles on progressive failure mode and

energy absorption capability of composite structures.

These failure modes under low-velocity impact loading

conditions are strongly dependent on the fibre type,

resin type, lay-up, thickness, loading velocity and

projectile type. For low-velocity impact events, the

usage of pendulums like the ones present in the

Charpy test2

and drop towers or drop weights3

hasbecome standard. The high-energy absorbing capabil-

ities of FRP composite materials are one of the main

factors in their application in automotive and aero-

space structures. They also provide other functional

and economic benefits such as enhanced strength, dur-

ability, weight reduction and hence lower fuel con-

sumption for structural vehicle crashworthiness. FRP

composites are able to collapse in a progressive, con-

trolled manner which results in high specific energy

absorption in the event of crash. Unlike metals and

polymers, the progressive energy absorption of com-

posite structures is dominated by extensive microfrac-

ture instead of plastic deformation.47

1Department of Mechanical Engineering, Hindustan College of Science &

Technology, India2Department Of Mechanical Engineering & Mining Machinery Engineering,

Indian School of Mines, India

Corresponding author:

Sandeep Agrawal, Department of Mechanical Engineering, Hindustan

College of Science & Technology, Farah, Mathura 281122, India.

Email: [email protected]

Journal of Composite Materials

2014, Vol 48(3) 317332

! The Author(s) 2012

Reprints and permissions:

sagepub.co.uk/journalsPermissions.nav

DOI: 10.1177/0021998312472217

jcm.sagepub.com

at EKB-Public-Access PARENT on January 14, 2016jcm.sagepub.comDownloaded from
http://jcm.sagepub.com/http://jcm.sagepub.com/http://jcm.sagepub.com/http://jcm.sagepub.com/


2/16

Impact

In general, impact damage is not considered to be a

threat in metallic structures because of the ductile

nature of the material and the large amount of energy

that can be absorbed. At yield stress, the material may

flow for very large strains at a constant rate before

work hardening, but the composites can fail in a widevariety of modes and contain impact damages visible by

a naked eye which severely reduces the structural dur-

ability of the component. Most composites are brittle

and so they can only absorb energy in elastic deform-

ation and through damage mechanisms, and not via

plastic deformation. The term damage resistance7

refers to the amount of impact damage which is

induced in a composite structure. Most of the impacts

on a composite structure will be in the transverse dir-

ection but due to the lack of through thickness

reinforcement, transverse damage resistance is particu-

larly poor. Interlaminar stresses (shear and tension) are

often the stresses that cause primary failure due to the

low interlaminar strengths. As a result, design failure

strains are used to guard against impact failure, result-

ing in a failure to take advantage of the excellent in-

plane strength and stiffness properties of composites.

Velocity of impact

Impacts are generally classified into three categories as

low-velocity impact, high-velocity impact and some-

times hyper velocity impact, but there is not a clear

transition between categories and authors disagree on

their definition.Sjoblom et al.8 and Shivakumar et al.9 define low-

velocity impact as events which can occur in the range

110 m/s depending on the target stiffness, material

properties and the impactor mass and stiffness.

High-velocity impact response is dominated by stress

wave propagation through the material in which the

structure does not have time to respond, leading to

much localised damage. Boundary condition effects

can be ignored because the impact event is over

before the stress waves have reached the edge of the

structure. In low-velocity impact, the dynamic struc-

tural response of the target is of utmost importance

as the contact duration is long enough for the entire

structure to respond to the impact and in consequence

more energy is absorbed elastically.

Cantwell and Morton10 conveniently classified low

velocity as up to 10 m/s, by considering the test tech-

niques which are generally employed in simulating the

impact event (instrumented falling weight impact test-

ing), Charpy, Izod, etc., whilst, in contrast, Abrate11 in

his review of impact on laminated composites stated

that low-velocity impacts occur for impact speeds of

less than l00 m/s.

Liu and Malvem12 and Joshi and Sun13 suggested

that the type of impact can be classified according to

the damage incurred, especially if damage is the prime

concern. High velocity is thus characterised by penetra-

tion-induced fibre breakage, and low velocity by delam-

ination and matrix cracking.

Davies and Robinson14,15

define a low-velocityimpact as being one in which the through-thickness

stress waveplays no significant part in the stress distri-

bution and suggest a simple model to give the transition

to high velocity. A cylindrical zone under the impactor

is considered to undergo a uniform strain as the stress

wave propagates through the plate, giving the compres-

sive strain as14

ec (Impact velocity/speed of sound in the material)

For failure strains between 0.5% and l%, this

gives the transition to stress wave dominated events

at 1020 m/s for epoxy composites.

Impact tests

To simulate actual impact by a foreign object, a

number of test procedures have been suggested by

many researchers. The initial kinetic energy of the pro-

jectile is an important parameter to be considered, but

several other factors also affect the response of the

structure. A large mass with low initial velocity may

not cause the same amount of damage as a smaller

mass with higher velocity, even if the kinetic energies

are exactly the same.

At the moment, two types of tests are used by most

investigators, although many details of the actual testapparatus may differ. Experimental studies attempt to

replicate actual situations under controlled conditions.

For example, during aircraft takeoff and landing,

debris flying from the runway can cause damage; this

situation, with small high-velocity projectiles, is best

simulated using a gas gun. Another concern is the

impact of a composite structure by a larger projectile

at low velocity which occurs when tools are accidentally

dropped on a structure. This situation is best simulated

using a drop weight tester.

Drop weight testers (Figure 1) are used extensively

and can be of different designs. Heavy impactors are

usually guided by a rail during free fall from a given

height.16 Usually, a sensor activates a mechanical

device designed to prevent multiple impacts after the

impactor bounces backup.

Pendulum-type systems (Charpy impact tests) are

used to generate low-velocity impacts. Pendulum-type

testers consist of a steel ball hanging from a string, or a

heavier projectile equipped with force transducers or

velocity sensors. The Hopkinson-type pressure bar

technique was also used. Ghasemnejad et al.17 used a

Charpy impact device consisting of three main parts of

318 Journal of Composite Materials 48(3)



3/16

specimens, anvil where the specimen is free supported

and also a pendulum with a defined mass attached to a

rotating arm pinned at the machine body. The Charpy

impact test rig with a dial and a pendulum is shown in

Figure 2. The dial gives readings of the absorbed energy

by the material during impact test which is measured in

Joules.

Parameters affecting impact damage

The extensive experimental work conducted upto now

created an understanding of the parameters that affect

the initiation and growth of impact damage. Material

properties affect the overall stiffness of the structure

and the contact stiffness and therefore will have a

significant effect on the dynamic response of the struc-

ture. Researchers and practitioners are also interested

in properties of the matrix, the fibres and the fibre

matrix interface which control the initiation and

growth of impact damage. The thickness of the lamin-

ates, the size of the panel and the boundary conditions

are all factors that influence the impact dynamics, sincethey control the stiffness of the target. The characteris-

tics of the projectile including its weight, shape, elastic

properties and incident angles are other parameters to

be considered. The layup, stitching, preload and envir-

onmental conditions are important factors which are to

be given attention.

Projectile characteristics

Impactor shape and weight of impactor play a signifi-

cant role in impact damage. In past research, the most

common impactor shape used has been hemispherical.

However, a dropped tool on a composite panel during

maintenance may not always impact the panel with a

blunt shape such as a hemisphere. Apart from the

common hemispherical impactor, some researchers

have used other impactor shapes such as flat-ended

and conical. These experiments have been conducted

under varying conditions, which make it impossible to

compare the results since there are many parameters

that can affect the impact response of composite lamin-

ates. Research which considered the effect of impactor

shape has predominantly been in the high-velocity

impact field where, for instance, the impact resistance

of armour has led to research into the ballistic limit ofprojectile shapes. However, it is known that specimens

react differently to high-velocity impacts where there is

a localised response compared to low-velocity impacts

where a global response may predominate.

Yang and Cantwell16 investigated the damage initi-

ation in glass fibre (GF) reinforced epoxy plates sub-

jected to low-velocity impact loading by considering the

effect of key parameters such as target size, projectile

diameter and test temperature on damage initiation.

The experimental data have been analysed using

simple energy based and stress-based models. The

results show that the damage initiation threshold

force, Pcrit varies with t3/2where t is the thickness of

the composite. For a given target thickness, the Pcritdoes not exhibit a dependency on the plate diameter

for the range of target geometries. It was also found

that at elevated temperature, the damaged threshold

also follows t3/2 dependency. The damage threshold

varied with projectile diameter with Pcrit increasing

steadily with increasing projectile diameter.

In Mitrevski et al.18, the effects of impactor shape

was investigated using hemispherical, ogival and

conical impactors as shown in Figure 3 on carbon/

Figure 1. The drop-weight impact tower.16

Agrawal et al. 319



4/16

epoxy laminates. It was found that the specimens

impacted by the conical impactor absorbed the most

energy and produced the largest penetration depth.

The blunter hemispherical impactor produced the lar-

gest peak force and shortest contact duration. The

damage threshold load was highest for the hemispher-

ical impactor followed by the ogival and conical impac-

tors, respectively.

The residual tensile and compressive strengths of

composite laminates are influenced by the damage

area and mechanisms induced by the impact.11,1924

Different impactor shapes will produce different

damage mechanisms and areas in composite laminates;

hence the residual properties of the material will change

according to the impactor shape. It is, therefore,

important to investigate the effects of different impactor

shapes on the damage resistance and tolerance of com-

posite laminates. Lee et al.25 conducted low-velocity

impact tests on simply supported sheet moulding

compound laminates. Conical, flat, hemispherical and

Figure 2. The Zwick/Roell Charpy test rig: (a) side view and (b) front view.17

Figure 3. (a) Hemispherical tup; (b) ogival tup; and (c) conical tup. 18




5/16

semi-cylinder impactors were used to impact specimens

of 2.4 mm thickness at initial impact energy of 54.5 J.

They found that flat and hemispherical impactors pro-

duced similar failure mechanisms and energy dissipa-

tion levels. The semi-cylindrical impactor produced a

vertically propagating crack (i.e. through thickness).

The local indentation induced by the flat and hemi-spherical impactors resulted in an increase in energy

dissipation compared to the semi-cylindrical impactor.

Local penetration was observed from the conical

impactor which resulted in the lowest dissipated

impact energy. They also found that the type of failure

mechanism induced by the impact affected the energy

dissipation capacity of the specimen. Using finite elem-

ent analysis, Kim and Goo26 modelled the effect of

altering the ratio between impactor nose lengths to

impactor radius, where a ratio of one represents a hemi-

spherical impactor, on the impact response of GF rein-

forced plastic (GFRP). The ratios tested were 0.1, 1 and

10. It was found that as the ratio decreased (became

more blunt), the peak force increased and the impact

duration decreased.

Zhou et al.27 applied a quasi-static load to nine-ply,

twill-weave, carbon/epoxy laminates with a nominal

thickness of 2 mm through hemispherical and flat

indentors of two sizes: 8 and 20 mm. The change in

indentor nose shape resulted in a change in failure

mode. For the hemispherical indentor, it was found

for most cases that matrix cracking initiated, followed

by fibre fracture. With the flat indentor, ply shear-out

was found to be the dominant failure mechanism since

stress concentration underneath the indentor spreadinto a greater area. This was also found by Zhou28

who used a flat impactor to impact various types of

GFRP. Under static test conditions, Mines et al.29

found flat and hemispherical impactors produced

larger delamination areas compared to a conical impac-

tor in both woven and z-stitched laminates of varying

thickness. This suggests that damage caused by conical

impactors is more localised, which is supported by the

local penetration found by Lee et al.25 Further research

is done under dynamic conditions to determine whether

the damage areas follow the trend produced under

static conditions by Mines et al.29

The influence of indentor geometry on damage

development in composite materials has been investi-

gated by a number of researchers.30,31 Siow and Shim32

showed that impactors with a small radius of curvature

produce a larger delamination area and greater fibre

breakage than those with a larger radius. Wakayama

et al.31 observed a change in failure mode from fibre

fracture to delamination as the impactor radius was

increased, during drop-weight impact tests on fila-

ment-wound carbon fibre reinforced plastics (CFRP)

pipes. Mitrevski et al.18 investigated the influence of

indentor shape on damage initiation in thin woven

CFRP laminates. They showed that hemispherical

indentors gave a higher peak force and shorter contact

duration than either conical or ogival impactors. The

hemispherical indentor resulted in barely visible impact

damage following a 4 J impact, whereas the sharper

indentors produced permanent indentation andpenetration.

Material properties

Mechanical properties of fibre-reinforced composites

are dependent on the properties of the constituent

materials (type, quantity, fibre distribution and orien-

tation and void content). Beside these properties, the

nature of the interfacial bonds and the mechanisms of

load transfer at the interface also play an important

role. If the building parts of composites differ in phys-

ical form and in chemical composition, only a weak

interaction can be developed at the interface. For

improving the adhesion between the matrix and the

fibres, there are varieties of modification technique

depending on the fibre and matrices type. One of

them is the application of coupling agents, which are

able to establish chemical bonds between the fibre and

the matrix due to their chemical composition. The price

of surface modifier chemicals is one of the key points in

the applicability of reinforced composites.33 Polyesters

could not be applied for technological purposes without

reinforcing because of low strength and brittleness, but

they are intensively used for composite matrices.34,35

The GF composites are the most wide spread amongfibre-reinforced materials due to their favourable mech-

anical and economical characteristics. For industrial

applications, the E- and S-type GFs are the most com-

monly used because they have the most favourable

cost-mechanical property relationships. Thermoset

composites have been applied in 1940s in aircraft indus-

try for the first time. Those materials were laminated

polyester composites, and the first application was the

cover of radar antennas because there was a need for

such non-metallic materials that allowed radio waves

through without distortion. The manufactured parts

were found to have better weight/volume ratio than

the ones made from metallic materials. Since then,

thermoset composites have been applied as construc-

tion materials. Current civil aircraft applications have

concentrated on replacing the secondary structure with

fibrous composites, where the reinforcement material

has either been carbon, glass, Kevlar, or hybrids of

those.36

Several authors have been studying the effect of

composite hybridisation on high-velocity impact behav-

iour.3739 Novak and De Crescente40 showed that the

addition of GF to CFRP and boron/epoxy system

Agrawal et al. 321



6/16

could improve the impact strength by a factor of 35.

Crack growth in hybrid fibrous composites was studied

by McColl and Morley.41 It was shown that the stabil-

ity of transverse crack in a very brittle matrix could be

increased substantially by inclusion of a second fibre

component designed specially to increase the work of

fracture of the matrix. Bunsell and Harris42

have shownthat the strips of GFRP incorporated into CFRP

laminates acts as efficient crack stoppers only if the

strip width is greater than a limiting value. This could

indicate that hybrids in which the different types of

fibre were more intimately mixed and not in well-

defined planes would not perform as well in terms of

fracture resistance. The same authors concluded that

the work of fracture by impact and the flexural elastic

modulus of mixed GFRP/CFRP composites are both

simple functions of composition corresponding to a

rule of mixture based on the properties of plain

GFRP and CFRP.43 Jang et al.44 showed that hybridis-

ing graphite composites with additional tough high

strain-to-failure fibres give better damage resistance of

composite structures under impact loading. The

obtained results also imply that the stacking sequence

is a major factor governing the overall energy absorb-

ing capability of the hybrid structure, and the penetra-

tion resistance of hybrid composites appeared to be

dictated by the toughness (strength plus ductility) of

their constituent fibres.45

Laminate thickness, layup and stitching

Target stiffness depends on material properties as wellas on the thickness of the laminate, the layup, its size

and the boundary conditions. The stiffness in the thick-

ness direction has a significant effect on the magnitude

of the maximum contact force which of course will

affect the extent of the damage induced.

The stacking sequence also plays a very important

role on the impact resistance of laminates. In a unidir-

ectional laminate, since the reinforcing fibres are all

oriented in the same direction, no delamination

occurs. For two plates with the same thickness but

with different stacking sequences, the one with the

higher differences of angle between two adjacent plies

will experience higher delamination areas. Increasing

the thickness of each layer will also lead to increased

delaminations. Increasing the difference between the

longitudinal and transverse moduli of the material

leads to higher bending stiffness mismatching and

therefore increased delaminations. However, damage

initiation is matrix- and interface-dependent and there-

fore has little or no dependence on the stacking

sequence. The peak load reached during impact or the

energy at peak load is strongly dependent on the stack-

ing sequence.11

Stitching is used to introduce through the thickness

reinforcement but in a different way than with weaving

or braiding. The laminated structure is preserved and

stitching can be performed on either a prepeg or pre-

form. Stitching density and pattern and properties of

the thread can be varied to improve delamination

resistance.Sadasivam and Mallick46 have studied the low-

energy impact characteristics of four different E-GF

reinforced thermoplastic and thermosetting matrix

composites. Low-energy impact caused dent on the

impacted side and surface cracks on the unimpacted

side of all four composites. The damage size, maximum

impact load, deflection at the maximum load and tup

velocity dissipation of the four composites are com-

pared. The residual tensile strength of the impact-

damaged composites is also determined as a function

of the input impact energy.

Caprino et al.47 have performed low-velocity impact

tests on carbon/epoxy laminates of different thick-

nesses. They have examined the force and absorbed

energy at the onset of delamination, the maximum

force and related energy and penetration energy.

From the experimental results, all these quantities,

except the energy for delamination initiation, followed

the same trend, increasing to the power of approxi-

mately 1.5 with increasing plate thickness. Some experi-

mental investigations have been carried out by Hosur

et al.48 to determine the response of four different com-

binations of hybrid laminates subjected to low-velocity

impact loading. They have indicated that there was

considerable improvement in the load-carrying capabil-ity of hybrid composites as compared to carbon/epoxy

laminates with slight reduction in stiffness. Datta

et al.49 have investigated the effects of variable impact

energy and laminate thickness on the low-velocity

impact damage tolerance of GFRP composite lamin-

ates. Critical values of impact energy and laminate

thickness were also defined. Baucom and Zikry50 have

conducted an experimental study to understand the

effects of reinforcement geometry on damage progress

in woven composite panels under repeated impact load-

ing. The composite systems included a two-dimensional

(2D) plain-woven laminate, a 3D orthogonally woven

monolith, and a bi-axially reinforced warp-knit. The

radial spread of damage was smallest for the 2D lamin-

ates and largest for the 3D woven composites. The 3D

composites had the greatest resistance to penetration

and dissipated more total energy than the other sys-

tems. Fuoss et al.51,52 have worked on the effects of

key stacking sequence parameters on the impact

damage resistance in composite laminates. A finite

element model using linear, quasi-static analysis

was developed to analyse the internal stress state

in the laminate and predict delamination damage.




7/16

A parameter based on bending strain is proposed as a

method of predicting the impact damage resistance in a

composite laminate with respect to changes in stacking

sequence. The method was evaluated by ranking lamin-

ates for damage resistance using the proposed param-

eter and comparing the results with existing

experimental and numerical results. The results weregenerally positive, as the damage resistance parameter

had a high linear correlation with the experimentally

measured or numerically predicted damage areas.

Rydin et al.53 have investigated the influence of

impact velocity on woven and non-woven composites.

For the range of impact velocities attainable in a typical

drop weight impact tower (


8/16

behaviour of glass/epoxy laminated composite plates

under low-velocity impact theoretically and experimen-

tally. Tita et al.69 have conducted experimental and

numerical studies to examine the stacking sequence

and impact energy effect on thin carbon/epoxy lami-

nated composite plates under low-velocity impact.

The influence of stacking sequence and energy impactwas investigated using loadtime histories, displace-

menttime histories and energytime histories as well

as images from NDE. Indentation tests results were

compared to dynamic results, verifying the inertia

effects when thin composite laminate was impacted by

foreign object with low velocity. For the experimental

approach, it is verified that stacking sequence and

impact energy level can influence the dynamic response

of composite plates. The graphs of forcetime and

energytime, as well as the images fromultrasonic

C-scan technique are used in order to compare the

mechanical behaviour of the specimens. The indenta-

tion test can be used to represent a drop-test when the

impact energy level is low and the specimen has a quasi-

elastic behaviour. Because the indentation curves do

not show the oscillations inherent in the dynamic

response obtained in drop-tests, there is more failure

mechanisms activated during the impact event than in

quasi-static event. Besides, the failure mechanisms

shown by the impact event are more distributed and

with a quasi-static event they are more concentrated.

Thus, the structural global stiffness reduces with more

intensity for drop-test. Finally, it is very important to

comment that the experimental test results for this

study were used to validate and calibrate a compositematerial failure model developed by the authors. Li

et al.70 have done an experimental and numerical inves-

tigation on low-velocity impact-induced damage of

continuous fibre-reinforced composite laminates.

Results show that the maximum contact force decreases

while the maximum deflection increases with increasing

of the plate thickness. In addition, the influence of the

boundary condition on the maximum contact force,

maximum deflection and delamination size is very

small. However, the impactor mass has a significant

effect on the impact behaviour of the composite plates.

Preload

Many researchers have analytically and experimentally

investigated the low-velocity impact behaviour of com-

posite laminated structures.70 Most composite struc-

tures will be under some level of stress when

impacted. For example, the upper layer of the main

wing of the aircraft will be mainly under in-plane com-

pressive load during flight and the lower one will be

under in-plane tensile load. So, foreign objects like

hail and debris in the runway shall give an impact to

composite laminated structure under in-plane load.

Very often, a composite structure experiences impact

loading in addition to the pre-existing stresses produced

either by service loads or by manufacturing/assembly

process. A common example is that of the structure of

an aircraft which during flight may experience bird-hit,

etc., while it is highly stressed due to various serviceloads. However, not much literature is available on

the impact response of composite structures with

prestresses.

Chen and Sun71 have developed a finite element pro-

gram to analyse the impact response of the composite

laminate under biaxial in-plane load. Using the finite

element program, they solved for three cases of in-plane

load, tension/tension load of three times of critical

buckling load of the plate, compression/compression

load of 75% of the critical bucking load and no initial

in-plane load. The impact condition is the case that the

mass of the impactor is very small and the impact vel-

ocity is very high. They concluded that the initial tensile

in-plane load tends to intensify the contact force while

reducing the contact time and an opposite conclusion is

obtained for an initial compressive in-plane load.

Except for this study, it is very rare to find another

analytical result on the impact behaviour of the com-

posite laminates under in-plane load. Kelkar et al.72

reported an experimental and analytical result on the

impact behaviour and the damage area through drop-

weight type impact test, which includes three cases of

thickness of the laminate (16, 32 and 48 plies) and four

cases of tensile in-plane load (0, 800, 1600 and 2400 me).

Their experimental result showed that as the initial in-plane load increases, the impact duration decreases and

the impact load increases. Also, it was observed that as

the initial in-plane load increases, in the case of 16-ply

laminates, the damage area increases. However, in the

case of 32-ply thick laminates, there was a marginal

increase in the damage area. In the case of 48-ply

thick laminates, for lower impact energy, there was a

marginal increase in the damage area. However, for

larger impact energy, there was a reduction in the

damage area. They tried an analytical prediction of

the damage area from quasi-static solution using com-

mercial finite element analysis software, but detailed

numerical output could not be found.72 Mitrevski

et al.73 presented the experimental results on the

impact behaviour of carbon/epoxy and glass/polyester

composite. They concluded that as the initial tensile in-

plane load increases, the contact duration decreases;

however, the initial tensile in-plane load has not

affected the maximum contact force and the damage

area. An experimental investigation on this aspect of

composite structures has been recently carried out by

Whittingham et al.74 In this study, laminated plates of

carbon fibre reinforced composites were subjected to




9/16

low-velocity impact while uniaxial or biaxial prestresses

already existed in the plane of the plates. Both tensile

and compressive preloads were used and impacts of two

magnitudes (measured in terms of impact energy) were

produced. It was shown that at low-impact energy, the

indentation depth and the peak load are independent of

the nature and magnitude of prestresses. Robb et al.75

investigated the damage phenomenon and damage tol-

erance of chopped strand matt laminates under impact

loading in the presence of uniaxial and biaxial pres-

tresses. It is observed that the shape, orientation and

size of the damage zone is strongly influenced by the

nature and magnitude of the prestrain. Impact speci-

mens subject to shear loading exhibit the largest

increase in damage area when compared to unstressed

plates.

Environmental conditions

A few researchers have also showed the effect of envir-

onmental aspects on impact damage such as low tem-

perature, UV rays, etc. Because most composite

structures are used outdoors, it cannot be avoided

that composite structures are subjected to various

environmental conditioning. The study of impact and

post impact response of laminated composites sub-

jected to environmental conditioning other than ambi-

ent is more realistic. Karasek et al.76 have evaluated the

influence of temperature and moisture on the impact

resistance of an epoxy/graphite composite. They have

found that only at elevated temperatures, the moisture

had a significant effect on damage initiation energy andthat the energy required for initiating damage had been

found to decrease with temperature. The investigations

by Bibo et al.77 have shown that temperature is capable

of altering the nature and extent of impact induced

damages. Parvatareddy et al.78 have investigated the

low-velocity impact behaviour of laminated composites

aged at elevated temperature in both air and nitrogen

environments. They have indicated that the ageing

environment has a significant effect on the residual ten-

sile strength. Hale et al.79 have found that the effect of

temperature and moisture is interactive. The loss of

strength and stiffness of laminated composites at ele-

vated temperatures is exacerbated by the increased rate

of water absorption at high temperatures. Li et al.80

have investigated the effect of cycling moisture on the

low-velocity impact behaviour of laminated composites

at elevated temperatures. Their results show that the

first moisture cycle has a significant effect on reducing

the low-velocity impact resistance of laminated com-

posites. Elevated temperature accelerates the damaging

effect of cycling moistures. Pang et al.81 have investi-

gated the effect of ultraviolet radiation on the low-

velocity impact response of laminated beams.

They have found that UV radiation alone has a signifi-

cant effect on reducing the residual load-carrying cap-

acity of impact damaged laminated beams. The

presence of water increased the damage effect of UV

radiation. Ibekwe et al.82 investigated low-velocity

impact response and post-impact compression buckling

strength of GF reinforced unidirectional and cross-plylaminated composite beams at low temperatures and

showed that the temperature has a significant effect

on the low-velocity impact responses of laminated com-

posites. More impact damage is induced in specimens

impacted at lower temperatures than those at higher

temperatures. The residual compressive buckling

strength and elastic modulus increase until a certain

point as temperature drops, at a much lower tempera-

ture both the residual compressive buckling strength

and the elastic modulus drop. It was also found that

the impact damage and the temperature have an oppos-

ite effect on the residual compressive buckling strength

and elastic modulus. The impact damage reduces the

residual compressive strength while the low tempera-

ture tends to increase it. Salehi-Khojin et al.83 investi-

gated the role of temperature on impact properties of

Kevlar/fibreglass composite laminates. In this investi-

gation, impact energy level and temperature were found

to have significant effects on the impact behaviour of

fibreglass and combinations of fibreglass with Kevlar.

At low impact energy, the amount of maximum

absorbed energy is almost constant and independent

of temperature. With increasing energy level, absorbed

energy becomes more and more dependent on tempera-

ture. At each of the impact energies, maximum deflec-tion is a function of impact energy and temperature

such that maximum deflection increases with a corres-

ponding increase in impact energy or temperature.

A few studies have focused on the effect of tempera-

ture on the impact response of polymer matrix compos-

ites. A decrease in delamination area was reported84

with increase in temperature in the range between

40C and 70C for a carbon fibre composite laminate

subjected to high energy impact. In a similar high-

velocity impact study on cross-ply laminates of poly-

ethylene fibre/epoxy matrix system,85 it was found that

the damage initiation energy doubled when the tem-

perature was increased from 50C to 100C. In con-

trast, laminates containing plain-weave fabrics showed

very little influence of temperature on the total impact

energy required for complete penetration of the speci-

men. Son and Kwon Young86 studied the effect of tem-

perature variation (30C to 120C) on damage to

orthotropic CFRP laminates at non-penetrating

impact velocities (upto 100 m/s). They observed a

linear relationship between the impact energy and the

delaminated area as well as an increase in the damage

area as the temperature decreased.

Agrawal et al. 325



10/16

Damage initiation

Impact damage usually follows some very complex dis-

tributions and it may not be possible to reconstruct the

entire sequence of events leading to a given damage

state. For low-velocity impact damage starts with the

creation of a matrix crack. In some cases, the target is

flexible and the crack is created by tensile flexural stres-ses in the bottom ply of laminate, this crack, which is

usually perpendicular to the plane of the laminate, is

called a tensile crack.2 For thick laminates, cracks

appear near the top of the laminate and are created

by the contact stresses. These cracks, called shear

cracks,2 are inclined relative to the mid-plane. Matrix

cracks induce delaminations at interfaces between adja-

cent plies and initiate a pattern of damage evolution

either from the bottom up or from the top down.

Therefore, while it is possible to predict the onset of

damage, a detailed prediction of the final damage

state cannot realistically be achieved.

Two types of approaches are used for predicting

impact damage. The first approach is aimed at predict-

ing the overall damage size. It is based on the premise

that delaminations, which are the critical component of

impact damage, grow because of high transverse shear

stresses in the vicinity of the impactor. The idea is to

determine the distribution of the transverse shear force

resultant around the point of impact and to use an

appropriate failure criterion to estimate the size of the

damage zone.

The second approach to be discussed here deals with

the prediction of the threshold value of the contact

force that corresponds to damage initiation. When thedamage area is plotted versus the maximum impact

force, there is a clear sudden increase in damage size

once the load reaches a critical value Pcrit. Below this

critical value, the damage area is small due to Hertzian

surface (a surface according to Hertz contact law) and

Pcrit corresponds to the onset delaminations.2

Under low-velocity impact loading conditions, the

time of contact between projectile and target are rela-

tively long. The load history can yield important infor-

mation concerning damage initiation and growth.8791

Several investigators used the force history to compare

the structural response from impact tests. As pointed

out in the literature, the first load drop, in terms of

Hertzian failure or significant damage corresponds to

the occurrence of initial damage in the form of matrix

cracking, fibre breakage and local puncture or indenta-

tion.8996 Davies and Zhang88 pointed out that the first

damage threshold is probably due to the initialisation

of delamination failure. Belingardi and Vadori91

defined two thresholds from the load history. The first

one was at the first load drop for the first material

damage and the second one was the maximum force

value for the first lamina failure.

Davies et al.87 proposed an equation for a critical

force threshold

P2crit 82Eh3GIIc=91v

2

wherePcritis the threshold load, Eand the equivalent

in-plane modulus and Poisson ratio, h the laminatethickness and GIIc the critical strain energy release

rate. The model indicates that the square of the critical

force threshold is proportional to the cube of the lamin-

ate thickness. The predictions from this equation for

delamination initiation agreed well with their experi-

mental data.88,89 Sjoblom97 also predicted that the crit-

ical damage initiation load should increase with t3/2.

However, some results showed that the delamination

threshold load varied with the laminate thickness to

the 3/2 power.90,97 Fibre failure occurs under the

impactor due to locally high stresses and indentation

effects. Belingardi and Vadori91 define a term of satur-

ation impact energy, which is the maximum energy

bearable by the material without perforation.

Dorey98 gives a simple equation for the energy

required for fibre failure and for penetration

E 2wtL=18Ef

whereis the flexural strength,Efthe flexural modulus,

w the width, L the unsupported length and t the speci-

men thickness.

Aktas et al.99 presented a schematic illustration for

different damage modes in composite laminates, as

shown in Figure 4.

Damage propagation

When a solid is subjected to any kind of loading, static

or impact, it can absorb energy by two basic mechan-

ism creations of new surfaces and material deform-

ation. The material deformation occurs first. If the

energy supplied is large enough, a crack may initiate

and propagate, thus actuating the second energy-

absorbing mechanism. The material deformation

continues in advance of the crack during crack propa-

gation. In the case of brittle materials such as glass and

other ceramics only a small amount of deformation

takes place. The associated energy absorbed is also

small. As a consequence, brittle materials exhibit a

low energy absorption capability.

Impact energy (Ei) and absorbed energy (Ea) are two

main parameters that can be used to assess damage

propagation in composite structures after an impact

event. Ei can be defined as the kinetic energy of the

impactor right before contactimpact takes place

while Ea is termed as the amount of energy absorbed

by the composite specimen at the end of an impact




11/16

event. Absorbed energy can be calculated from load

deflection (Fd) curves. Figure 5 shows two typical Fd

curves encountered in an impact event. Shaded areas in

Figure 5(a) and (b) represent the energies absorbed by

specimens during impact tests resulting in closed- and

open-type curves, respectively. Open-type Fd curves

have a horizontal section at the very end, post-

perforation frictional section. In order to identify the

true energy absorption due to damage formation in the

specimens, the post-perforation frictional sections need

to be removed from the curves.100 For this purpose, the

ending part of the descending section of the Fdcurve

may be extended to the deflection axis, shown as the

dashed line in Figure 5(b).

Karakuzu et al.101 plotted the impact energy versus

the absorbed energy for equal mass and equal velocity

as shown in Figure 6 using energy profiling dia-

grams.59,61 That is, variation of the absorbed energy

versus impact energy is plotted for two equal param-

eters; mass and velocity. It is clearly observed from

Figure 6 that all the specimens are of the rebounding

case. However, the specimen subjected to 40 J for equal

Figure 4. Schematic illustrations for different damage modes.99

Figure 5. Calculation of the absorbed energy from loaddeflection curves for a non-perforated specimen (a) and a perforated

specimen (b).100

Agrawal et al. 327



12/16

velocity has reached the penetration threshold. In add-

ition, the energy absorption capability of the specimen

subjected to equal mass is lower than the specimen sub-

jected to equal velocity, for the same impact energy.

They have carried out an experimental and numer-

ical study to investigate the effect of the equal impact

energy (40 J), equal impactor mass (5 kg) and equal vel-

ocity (2 m/s) on the contact force, deflection, contact

time, damage area and absorbed energy of glass/

epoxy laminated composite plates by taking the orien-

tation [0/30/60/90]s. The equal impact energy

remained constant by changing the impact velocity or

the impactor mass. The numerical analysis was done

using 3DIMPACT finite element code. Results show

that the energy absorption capability of the specimens

subjected to equal mass is lower than the specimens

Figure 6. Energy profiling diagram for the experimental results.101

Figure 7. The variation of impact energy versus (a) maximum contact force, (b) maximum deflection and (c) contact time dependingon the equal mass and the equal velocity.101




13/16

subjected to equal velocities and the effects of the equal

mass and the equal velocity on the maximum contact

force and maximum deflection are nearly the same

while the impact energy increases. For a better under-

standing of the impact behaviour of glass/epoxy com-

posite plates, only the maximum values of the contact

force, maximum deflection and contact time are shownin Figure 7. As observed from the figure, the equal mass

and the equal velocity have nearly the same effects on

the maximum contact force and maximum deflection

while the impact energy increases (Figure 7(a) and

(b)). However, the effect of both on the contact time

differs from each other (Figure 7(c)).

The various mechanisms involved during crack

propagation account for the total energy absorbed in

a fracture process. Obviously, the same mechanisms

will not be important in all combinations of matrix

and fibre materials. No single mechanism can account

for the observed toughness of composites. The various

failure mechanisms are fibre breakage, matrix deform-

ation and cracking, fibre debonding, fibre pullout and

delamination cracks.

Spall strength of GFs reinforced epoxy composites

were measured by Zaretsky et al.102 It was found that

three possible failure modes as debonding, delamin-

ation and matrix cracking for the composite resulted

in large variations of the spall strength. A nucleation

and growth model together with a fracture model that

were applied by Tokheim et al.,103 provided good esti-

mates for corresponding experimental measurements of

spall strength in a Kevlar fibres reinforced epoxy com-

posite. Delamination strength of GFs reinforced com-posites were measured by Dandekar et al.104 under

plane normal and oblique impact conditions. A thresh-

old shock-induced compression stress beyond which

delamination will occur due to refracted tensile waves

was determined. The values of the threshold and delam-

ination tensile stresses were found to depend strongly

on the angle of the impact relative to the fibres plane.

Syam et al.105 examined the fracture mechanism in rein-

forced plastics. It was found that the damage zone con-

sisted of matrix cracking, fractured fibres and

debonding between the fibres and the matrix.

Conclusion

There has been a growing interest, particularly in the

past few decades, in the use of composite materials in

structural applications ranging from aircraft and space

structures to automotive and biomedical applications.

However, their behaviour under impact loading is one

of the major concerns, since impacts do occur during

manufacture, normal operations, maintenance, etc.

Especially, unidirectional laminated plates are highly

susceptible to the transverse impact loads resulting in

significant damages such as matrix cracks, delamin-

ations and fibre fractures. Numerous studies on the

impact response of composite materials and structures

can be found in review papers.

Low-velocity impact refers to impacts in the range

110 m/s which are ordinarily introduced in the labora-

tory by mechanical test machines. The contact period issuch that the whole structure has time to respond to the

loading. The modes of impact damage induced range

from matrix cracking and delamination through to

fibre failure and penetration. Damage mode interaction

must also be understood when attempting to predict

initiation and propagation of a particular form of

damage. Toughened resins or thermoplastics can

reduce matrix-dominated damage but the fibres have

the most bearing on impact response and over the

narrow velocity range under consideration, the strain

rate sensitivity of fibres can be ignored. Post-impact

performance is related to the major damage mode;

therefore, a combination of tension and compression

residual strength testing is required to characterise the

laminate.

Polymer-matrix composites are known to be highly

susceptible to internal damage caused by transverse

loads even under low-velocity impacts. The composites

can be damaged on the surface. They can also be

damaged beneath the surface by relatively light impacts

causing barely visible impact damage, while the surface

may appear to be undamaged to visual inspection. For

the effective use of polymer-matrix composites for high-

performance applications, understanding the causes

of the formation of such damage when subjected tolow- and high-velocity impact and improving the

damage-resistance characteristics of the composites are

important considerations. Vast research has been per-

formed on simple geometry carbon/epoxy cross-ply

laminates consistingof plies at various fibre orientations,

due to their importance in the aerospace industry. The

low-velocity impact response of random fibre/unidirec-

tional laminate combinations and impacts on complex

geometry are less well documented, and more research

work is required in these areas if composite laminates are

to be employed in more structural applications.

Funding

This research received no specific grant from any funding

agency in the public, commercial, or not-for-profit sectors.

Conflict of interest

None declared.

References

1. Erbil E. Impact loading in laminated composites. MSc

Thesis, DokuzEylu l University, Turkey, 2008.

Agrawal et al. 329



14/16

2. Abrate S. Impact on composites structures. Cambridge:

Cambridge University Press, 1998.

3. Richardson MOW and Wisheart MJ. Review of low-

velocity impact properties of composite materials.

Composites Part A 1996; 27A: 11231131.

4. Hull D. A unified approach to progressive crushing of

fibre reinforced tubes. Compos Sci Technol 1991; 40:

377421.5. Farley G and Jones R. Crushing characteristics of con-

tinuous fibre reinforced composite tubes. J Compos

Mater 1992; 26: 3750.

6. Fairfull A and Hull D. Energy absorption of polymer

matrix composite structures: frictional effects.

In: Wierzbicki T and Jones D (eds) Structural failure.

New York: John Wiley and Sons, 1989, pp.255279.

7. Mamalis AG, Manolakos DE, Demosthenous GA, et al.

The static and dynamic collapse of fibre glass composite

automotive frame rails. Compos Struct 1996; 34: 7790.

8. Sjoblom PO, Hartness JT and Cordell TM. On low-

velocity impact testing of composite materials.

J Compos Mater 1988; 22: 3052.9. Shivakumar KN, Elber W and Illg W. Prediction of low

velocity impact damage in thin circular laminates. AIAA

J1985; 23(3): 442449.

10. Cantwell WJ and Morton J. The impact resistance of

composite materials a review. Composites 1991; 22(5):

347362.

11. Abrate S. Impact on laminated composite materials.Appl

Mech Rev 1991; 44(4): 155190.

12. Liu D and Malvem LE. Matrix cracking in impacted

glass/epoxy plates. J Compos Mater 1987; 21: 594609.

13. Joshi SP and Sun CT. Impact-induced fracture initiation

and detailed dynamic stress field in the vicinity of impact.

In: Proceedings of American Society of Composites 2nd

technical conference, Newark, DE, 2325 September1987, pp. 177185.

14. Robinson P and Davies GAO. Impactor mass and speci-

men geometry effects in low velocity impact of laminated

composites. Int J Impact Eng 1992; 12(2): 189207.

15. Davies DAO and Robinson P. Predicting failure by

debonding/delamination. In: AGARD: 74th structures

and materials meeting, Patras, Greece, 2529 May 1992.

16. Yang FJ and Cantwell WJ. Impact damage initiation in

composite materials. Compos Sci Technol 2010; 70:

336342.

17. Ghasemnejad H, Furquan ASM and Mason PJ. Charpy

impact damage behaviour of single and multi delami-

nated hybrid composite beam structures. Mater Des

2010; 31: 36533660.

18. Mitrevski T, Marshall IH, Thomson R, et al. The effect

of impactor shape on the impact response of composite

laminates. Compos Struct 2005; 67: 139148.

19. Caprino G. Residual strength prediction of impacted

CFRP laminates. Compos Mater 1984; 18: 508518.

20. Davies GAO, Hitchings D and Zhou G. Impact damage

and residual strengths of woven fabric glass/polyester

laminates. Composite Part A 1996; 27A: 11471156.

21. Cantwell WJ and Morton J. Comparison of the low and

high velocity impact response of CFRP.Composites1989;

20(6): 545551.

22. Prichard JC and Hogg PJ. The role of impact damage in

post-impact compression testing. Composites 1990; 21(6):

503509.

23. Hitchen SA and Kemp RMJ. The effect of stacking

sequence on impact damage in a carbon fibre/epoxy com-

posite. Composites 1995; 26(3): 207214.

24. Benzeggagh ML and Benmedakhene S. Residual strength

of a glass/polypropylene composite material subjected toimpact. Compos Sci Technol1995; 55: 111.

25. Lee SM, Cheon JS and Im YT. Experimental and numer-

ical study of the impact behavior of SMC plates. Compos

Struct 1999; 47: 551561.

26. Kim SJ and Goo NS. Dynamic contact responses of lami-

nated composite plates according to the impactors

shapes. Compos Struct 1997; 65(1): 8390.

27. Zhou G, Lloyd JC and McGuirk JJ. Experimental evalu-

ation of geometric factors affecting damage mechanisms

in carbon/epoxy plates. Composites Part A 2001; 32:

7184.

28. Zhou G. Damage mechanisms in composite laminates

impacted by a flat-ended impactor. Compos Sci Technol1995; 54: 267273.

29. Mines RAW, Roach AM and Jones N. High velocity

perforation behaviour or polymer composite laminates.

Int J Impact Eng 1999; 22: 561588.

30. Zhou G. Prediction of impact damage thresholds of glass

fibre reinforced laminates. Compos Struct 1995; 31:

185193.

31. Wakayama S, Kobayashi S, Imai T, et al. Evaluation of

burst strength of FW-FRP composite pipes after impact

using pitch-based low-modulus carbon fibre. Composites

Part A 2006; 37: 20022010.

32. Siow YP and Shim VPW. An experimental study of low

velocity impact damage in woven fibre composites.

J Compos Mater 1998; 32: 11781202.33. Varga Cs, Miskolczi N, Bartha L, et al. Improving the

mechanical properties of glass-fibre reinforced polyester

composites by modification of fibre surface. Mater Des

2010; 31: 185193.

34. Skrifvars M, Mackin T and Skagernerg B. An application

of experimental design to the development of glass fibre

reinforced polyester laminates with enhanced mechanical

properties. Polym Test 1998; 17(5): 345356.

35. Bagherpour S, Bagheri R and Saatchi A. Effects of con-

centrated HCl on the mechanical properties of storage

aged fibre glass polyester composite. Mater Des 2009;

30: 271274.

36. Soutis C. Carbon fibre reinforced plastic in aircraft con-

struction. Mater Sci Eng A 2005; 412(12): 171176.

37. Marom G, Fischer S, Tuler FR, et al. Hybrid effects in

composites: conditions for positive or negative effects

versus rule-of-mixture behavior. J Mater Sci 1978; 13:

14191426.

38. Zweben C. Tensile strength of hybrid composites.

J Mater Sci1977; 12: 13251337.

39. Manders PW and Bader MG. The strength of hybrid

glass/carbon fibre composites. J Mater Sci 1981; 16:

22332245.

40. Novak RC and De Crescente MA. Impact behavior of

unidirectional resin matrix composites tested in the fibre




15/16

direction. In: Composite materials: testing and design

(second conference), ASTM-STP 497, Anaheim, CA,

2022 April 1971, pp.311323, 1971.

41. McColl IR and Morley JG. Crack growth in hybrid

fibrous composites. J Mater Sci1977; 12: 11651175.

42. Bunsell AR and Harris B. Hybrid carbon and glass fibre

composites. Composites 1974; 5: 157164.

43. Harris B and Bunsell AR. Impact properties of glass

fibre/carbon fibre hybrid composites. Composites 1975;

7: 197201.

44. Jang BZ, Chen LC, Wang CZ, et al. Impact resistance

and energy absorption mechanisms in hybrid composites.

Compos Sci Technol1989; 34: 305335.

45. Muhi RJ, Najim F and de Moura MFSF. The effect of

hybridization on the GFRP behavior under high velocity

impact. Composites Part B 2009; 40: 798803.

46. Sadasivam B and Mallick PK. Impact damage resistance

of random fibre reinforced automotive composites.

J Thermoplast Compos Mater 2002; 15: 181191.

47. Caprino G, Lopresto V, Scarponi C, et al. Influence of

material thickness on the response of carbonfabric/epoxy panels to low velocity impact. Compos Sci

Technol1999; 59: 22792286.

48. Hosur MV, Adbullah M and Jeelani S. Studies on the

low-velocity impact response of woven hybrid compos-

ites. Compos Struct 2005; 67: 253262.

49. Datta S, Krishna AV and Rao RMVGK. Low velocity

impact damage tolerance studies on glassepoxy lamin-

ates effects of material, process and test parameters.

J Reinf Plast Compos 2004; 23(3): 327345.

50. Baucom JN and Zikry MA. Low-velocity impact damage

progression in woven E-glass composite systems.

Composite Part A 2005; 36(5): 658664.

51. Fuoss E, Straznicky PV and Poon C. Effects of stacking

sequence on the impact resistance in composite laminates

Part 1: parametric study. Compos Struct 1998; 41:

6777.

52. Fuoss E, Straznicky PV and Poon C. Effects of stacking

sequence on the impact resistance in composite laminates.

Part 2: prediction method. Compos Struct 1998; 41:

177186.

53. Rydin RW, Bushman MB and Karbhari VM. The influ-

ence of velocity in low velocity impact testing of compos-

ites using the drop weight impact tower. J Reinf Plast

Compos 1995; 14: 113127.

54. Kim J-K and Sham M-L. Impact and delamination fail-

ure of woven fabric composites. Compos Sci Technol

2000; 60: 745763.55. Naik NK, Sekher YC and Meduri S. Polymer matrix

woven fabric composites subjected to low velocity

impact: Part IIeffect of plate thickness. J Reinf Plast

Compos 2000; 19: 10311055.

56. Naik NK, Borade SV, Arya H, et al. Experimental stu-

dies on impact behavior of woven fabric composites:

effect of impact parameters. J Reinf Plast Compos 2002;

21: 13471362.

57. Atas C and Dahsin L. Impact response of woven com-

posites with small weaving angles. Int J Impact Eng 2008;

35(2): 8097.

58. Liu D. Characterization of impact properties and damage

process of glass/epoxy composite laminates. J Compos

Mater 2004; 38: 14251442.

59. Liu D, Raju BB and Dang X. Impact perforation resist-

ance of laminated and assembled composite plates. Int J

Impact Eng 2000; 24(6): 733746.

60. Symons DD. Characterisation of indention damage in 0/

90 lay-up T300/914 CFRP. Compos Sci Technol 2000;60(3): 391401.

61. Aktas M, Atas C, Icten BM, et al. An experimental inves-

tigation on impact response of unidirectional composite

laminates. Compos Struct 2009; 87(4): 307313.

62. Icten BM, Atas C, Aktas M, et al. Low temperature effect

on impact response of quasi-isotropic glass/epoxy lami-

nated plates. Compos Struct 2009; 91: 318323.

63. Freitas M, Silva A and Reis L. Numerical evaluation

of failure mechanisms on composite specimens subjected

to impact loading. Composite Part B 2000; 31(3):

199207.

64. Zhang Y, Zhu P and Lai X. Finite element analysis of

low-velocity impact damage in composite laminatedplates. Mater Des 2006; 27: 513519.

65. Olsson R, Donadon MV and Falzon BG. Delamination

threshold load for dynamicimpact on plates. Int J Solids

Struct 2006; 43(10): 31243141.

66. Aslan Z, Karakuzu R and Okutan B. The response of

laminated composite plates under low-velocity impact

loading. Compos Struct 2003; 59(1): 119127.

67. Tiberkak R, Bachene M, Rechak S, et al. Damage pre-

diction in composite plates subjected to low velocity

impact. Compos Struct 2008; 83(1): 7382.

68. Mili F and Necib B. Impact behavior of cross-ply lami-

nated composite plates underlow velocities. Compos

Struct 2001; 51(3): 237244.

69. Tita V, Carvalho J and Vandepitte D. Failure analysis oflow velocity impact on thin composite laminates: experi-

mental and numerical approaches. Compos Struct 2008;

83(4): 413428.

70. Li CF, Hu N, Cheng JG, et al. Low-velocity impact-

induced damage of continuous fibre-reinforced composite

laminates, part II. Verification and numerical investiga-

tion. Composite Part A 2002; 33: 10631072.

71. Chen JK and Sun CT. Dynamic large deflection response

of composite laminates subjected to impact. Compos

Struct 1985; 4: 5973.

72. Kelkar AD, Sankar J, Rajeev K, et al. Analysis of tensile

preloaded composites subjected to low-velocity impact

loads. In: 39th AIAA/ASME/ASCE/AHS/ASC struc-

tures, structural dynamics, and materials conference and

exhibit and AIAA/ASME/AHS adaptive structures 7

Forum, Long Beach, CA, 2023 April 1998, pp. 1978

1987.

73. Mitrevski T, Marshall IH, Thomson RS, et al. Low-

velocity impacts on preloaded GFRP specimens with

various impactor shapes. Compos Struct 2006; 76:

209217.

74. Whittingham B, Marshall IH, Mitrevski T, et al. The

response of composite structures with pre-stress subject

to low velocity impact damage. Compos Struct 2004; 66:

685698.

Agrawal et al. 331



16/16

75. Robb MD, Arnold WS and Marshall IH. The damage

tolerance of GRP laminates under biaxial prestress.

Compos Struct 1995; 32: 141149.

76. Karasek ML, Strait LH, Amateau MF, et al. Effect of

temperature and moisture on the impact behavior of

graphite/epoxy composites: part IIimpact damage.

J Compos Technol Res JCTR 1995; 171: 1116.

77. Bibo GA, Leicy D, Hogg PJ, et al. High temperaturedamage tolerance of carbon fibre-reinforced plastics. 1:

impact characteristics. Composites 1994; 25(6): 414424.

78. Parvatareddy H, Wang JZ, Dillard DA, et al.

Environmental aging of high performance polymeric

composite: effects on durability. Compos Sci Technol

1995; 53: 399409.

79. Hale JM, Gibson AG and Speake SD. Tensile strength

testing of GRP pipes at elevated temperatures in aggres-

sive offshore environments. J Compos Mater 1998;

32(10): 969986.

80. Li G, Pang SS, Helms JE, et al. Low velocity impact

response of GFRP laminates subjected to cycling mois-

ture. Polym Compos 2000; 21(5): 686695.81. Pang SS, Li G, Helms JE, et al. Influence of ultraviolet

radiation on the low velocity impact response of lami-

nated beams. Composite Part B 2001; 32(6): 521528.

82. Ibekwe SI, Mensah PF, Li G, et al. Impact and post

impact response of laminated beams at low temperatures.

Compos Struct 2007; 79: 1217.

83. Salehi-Khojin A, Bashirzadeh R, Mahinfalah M, et al.

The role of temperature on impact properties of

Kevlar/fibreglass composite laminates. Composites Part

B 2006; 37: 593602.

84. Levin K. Effect of low velocity impact on compression

strength of quasi-isotropic laminate. In: Proceedings of

American Society for Composites: first technical confer-

ence, Marriott Hotel, Dayton, OH, 79 October 1986,pp.313325. Lancaster, PA: Technomic Publishing

Company.

85. Zimmerman RS and Adams DF. Impact performance of

various fibre reinforced composites as a function of tem-

perature. In: Proceedings of 32nd International SAMPE

symposium, Anaheim, CA, 69 April 1987, pp.14611471.

86. Son KH and Kwon Young J. Effects of temperature on

impact damages in CFRP composite laminates.

Composites Part B 2001; 32: 669682.

87. Davies GAO, Zhang X, Zhou G, et al. Numerical mod-

eling of impact damage.Composites1994; 25(5): 342350.

88. Davies GAO and Zhang X. Impact damage prediction in

carbon composite structure.Int J Impact Eng1994; 16(1):

149170.

89. Zhang X. Impact damage in composite aircraft struc-

turesexperimental; testing and numerical simulation.

Proc IMechE Part G: J Aerospace Engineering 1998;

212: 245259.

90. Schoeppner GA and Abrate S. Delamination threshold

loads for low velocity impact on composite laminates.

Composites Part A 2000; 31: 903915.

91. Belingardi G and Vadori R. Low velocity impact tests of

laminate glass-fibre-epoxy matrix composite material

plates. Int J Impact Eng 2002; 27: 213229.

92. Matemilola SA and Stronge WJ. Low speed impact

damage infilament-wound CFRP composite pressure

vessels.J Pressure Vessel Technol1997; 119(4): 435443.

93. Alderson KL and Evans KE. Failure mechanisms

during the transverse loading of filament-wound pipesunder static and low velocity impact conditions.

Composites 1992; 23(3): 167173.

94. Hirai Y, Hamada H and Kim JK. Impact response of

woven glass fabric composites effect of fibre surface

treatment.Compos Sci Technol1998; 58(1): 91105.

95. Zhou G. The use of experimentally-determined impact

force as damage measure in impact damage resistance

and tolerance of composite structures. Compos Struct

1998; 42: 375382.

96. Cartie DDR and Irving PE. Effect of resin and fibre

properties on impact and compression after impact per-

formance of CFRP. Composites Part A 2002; 33:

483493.97. Sjoblom P. Simple design approach against low velocity

impact damage. In: Proceedings of 32nd SAMPE sym-

posium, Anaheim, CA, 69 April 1987, pp.529539.

98. Dorey G. Impact damage in compositesdevelopment,

consequences, and prevention. In:Proceedings of the 6th

international conference on composite materials and 2nd

European conference on composite materials, Imperial

College, London, UK, 1988, vol. 3, pp.3.13.26.

99. Aktas M, Atas C, Icten BM, et al. An experimental

investigation of the impact response of composite lamin-

ates. Compos Struct 2009; 87: 307313.

100. Atas C and Sayman O. An overall view on impact

response of woven fabric composite plates. Compos

Struct 2008; 82: 336345.101. Karakuzu R, Erbil E and Aktas M. Impact character-

ization of glass/epoxy composite plates: an experimental

and numerical study. Composites Part B 2010; 41:

388395.

102. Zaretsky E, Igra O, Zhuk AZ, et al. Deformation modes

in fibreglass under weak impact. J Reinf Plast Compos

1997; 16: 321331.

103. Tokheim RE, Erlich DC and Kobayshi T.

Characterization of spall in Kevlar/epoxy composite.

In: Schmidt SC, Johnson JN and Davison LW (eds)

Shock compression of condensed matter. Amsterdam:

Elsevier, 1989, pp.473476.

104. Dandekar DP, Boteler JM and Beaulieu PA. Elastic

constants and delamination strength of a glass-

fibre-reinforced polymer composite. Compos Sci

Technol1998; 58: 13971403.

105. Syam B, Homma H and Nakazato K. Fracture behav-

iors of GFRP plates subjected to impulsive loading.Key

Eng Mater 2000; 183187: 893898. In: Fracture and

strength of solids, Zurich-Uetikon: Trans Tech

Publications.


impact damage on fibre-reinforced.pdf

Documents