impact damage behaviour of shape memory alloy composites

Impact damage behaviour of shape memory alloy composites

Kelly A. Tsoi a,*, Rudy Stalmans b, Jan Schrooten a, Martine Wevers a, Yiu-Wing Mai c

a Department of Metallurgy and Materials Engineering, Katholieke Universiteit Leuven, Leuven, Belgiumb FLEXMET, Rillaarsebaan 233, B-3200, Aarschot, Belgium

c School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, Australia

Received 31 December 2001; received in revised form 24 April 2002

Abstract

Currently there is an increased interest in the use of shape memory alloy composites (SMA composites). Many potential uses have

been found for SMA composites, for example, in shape control and vibration control. However there is not a lot of information

available on the properties of SMA composites since it is still a relatively new area. Recent investigations have been conducted on

their transformational behaviour, which provides the valuable first step information required for implementing these composites

into real structures. However, further work still needs to be completed on other aspects of these composites. This article investigates

the impact damage behaviour of SMA-composites. The results show that for low velocity impact, embedding SMA wires into

composites does not compromise the structure any differently to composites without wires. In fact, it has been shown that for some

cases there is an improvement in the damage resistance of the composites.

# 2002 Elsevier Science B.V. All rights reserved.

Keywords: Shape memory alloys; Adaptive composites; Low velocity impact damage; Superelasticity

1. Introduction

Composite materials are commonly used in structures

which require lightweight, yet strong components.

However there is an increased interest in the use of

embedded shape memory alloy wires in composites to

enhance structural performance, either in vibration

control, or shape control [1�/5]. In general one wants

to create adaptive composites.

Not a lot of research has been conducted on the

behaviour of SMA-composites. Recent research has

determined the transformational behaviour of SMA

composites [6�/9], the vibrational behaviour [1�/5] and

the microscopic properties such as interfacial shear

strength [10�/12] and the stress distribution in the

SMA composites during activation of the wires [13,14].

1.1. SMA-composites

An important factor to whether SMA composites can

be used reliably in daily structures is the behaviour of

the composites during impact. Composite structures in

general are susceptible to a wide range of damage and

defects [15] which are produced during manufacture as

well as during service. Impact damage is one of the

problems that composite structures face, there is simply

no way to avoid impact damage during service, so there

needs to be a way of reducing that damage when it

occurs, reducing it enough so that the integrity of the

structure is not compromised. If these SMA composites

are to be used in structures such as aircraft, high speed

trains and cars, to name but a few applications, the

behaviour of the composites during impact and the

effects of having the wires embedded inside the compo-

sites must be well understood.There are several questions which need to be an-

swered with respect to impact damage when embedding

SMA wires into composites. Firstly if the wires are pre-

strained before embedding, and for many applications

this must be the case, there will be a thermal stress

mismatch during curing. Will these stresses be released

* Corresponding author. Present address: DSTO, 506 Lorimer St.,

3207 Fishermans Bend, UIC, Australia

E-mail address: [email protected] (K.A. Tsoi).

Materials Science and Engineering A342 (2003) 207�/215

www.elsevier.com/locate/msea

0921-5093/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.

PII: S 0 9 2 1 - 5 0 9 3 ( 0 2 ) 0 0 3 1 7 - 9

mailto:[email protected]

when an embedded wire is impacted, causing greater

damage, or will there be an improvement in the impact

damage resistance? Paine and Rogers, [16], investigated

the use of superelastic SMA’s embedded into compositematerials to improve the low velocity impact damage of

laminates. They used a cross-ply layup of [028,9028,028] of

graphite/bismaleimide composites with the superelastic

NiTi SMA wires, of diameter 0.3 mm, with no pre-

strain, embedded in the lower 08/908 interface. The

volume fraction of the SMA wires was 2.8%. During the

impact of the specimens they found that their specimens

weren’t clamped sufficiently and they underwent largedeflections and slippage. For these specimens they used

a visual inspection method to compare the amount of

impact damage. On comparison with the reference

graphite laminate it was found that for high-energy

impacts of 18 and 23 J, the SMA wires in the hybrid

laminate prevented complete perforation during the

impact. It was also found that the all graphite laminate

had a larger visible delamination than the hybridcomposite. Paine and Rogers, [16], also used a special

clamping device in order to secure the specimens and to

obtain smaller deflections during impact. For these

samples they found it was more difficult to see

differences in the damage based on a visual inspection.

At the highest impact energy level of 14 J, all graphite

laminate specimens underwent complete perforation

whereas with the hybrid specimens only the layers abovethe SMA wire layer were perforated. It was also

determined that the peak impact forces of the hybrid

specimens were much higher than the all graphite

specimens. The delaminations in the centre of the

laminate were similar in size for both types of specimens.

These results suggest that SMA wires embedded into

composites can actually improve the impact resistance,

at least for simple cross ply layups. However, forapplications to structures, it is rare that cross ply layups

are used and hence an investigation into a multi angle

ply layup is justified and will be discussed in this paper.

1.2. Superelastic SMA

The embedment of superelastic SMA’s was also

investigated, because these wires are able to absorb

and dissipate impact energy which is not the case forother metal wires. Superelastic shape memory alloys

exhibit the property of being able to be completely

deformed at room temperature and returning to their

original shape after unloading. The mechanism behind

superelasticity is the stress induced martensitic transfor-

mation. Normally martensite is formed as the alloy

cools to below a temperature, Ms, under no stress. On

heating, the reverse transformation from martensite toaustenite starts at As and finishes at a temperature, Af. It

is also possible for martensite to be formed above Ms, by

the application of stress. The resulting martensite is

known as stress induced martensite (SIM), and the

transformation of it from its austenitic parent phase is

fully mechanical. There is a thermal limit to when SIM

will no longer be formed and this occurs at temperaturesabove Md, at which the stress required to form SIM is

greater than that needed to move dislocations. Hence,

SIM is formed at temperatures, MsB/T B/Md. Complete

superelasticity occurs when SIM is formed above the

austenitic transformation temperature, Af, but below

Md. When a SMA is heated above its transformation

temperature it becomes austenitic. If a stress is then

applied to the alloy in this state, large deformationstrains can be obtained and SIM is formed. Upon

removal of the stress, the martensite reverts to its

austenitic parent phase and recoverable strains of up

to 8% can be achieved [17].

By embedding these SMA’s into a composite struc-

ture, impact energy will be absorbed by the wires,

transforming them from austenite to martensite. After-

wards the energy is released again by the reversetransformation. Superelastic SMA composites may be

able to improve the damping of structures. This

reversible phenomenon does not occur for other metal

wires.

With this current investigation a series of different

types of wires, including superelastic, martensitic NiTi

and NiTiCu and steel wires, were embedded at different

through thickness positions within a glass/epoxy matrixwith differing pre-strains ranging from no pre-strain to

3%. Differing from previous research efforts, an inves-

tigation into the effects of different volume fractions (Vf)

of SMA wires in the specimens was also made.

2. Materials and methods

2.1. Materials

SMA composite specimens of 125�/125 mm2 were

produced using Strafil G-EPI-140/142 glass fibre epoxy

pre-preg, from Hexcel composites and several different

types of wires. A superelastic 55.1 wt.% Ni balance Ti

wire, straight annealed, obtained from Thomas Bolton

Inc, a martensitic shape memory NiTi wire from SMA,

Inc. (USA), a ternary NiTiCu wire with a singletransformation from Memry (USA), and annealed

stainless steel wires, all of 0.15 mm diameter, were

used. The superelastic wires have a transformation

temperature below zero and were embedded while in

their austenitic state. The binary NiTi wires have

transformation temperatures, Ms�/39.8 8C, Mf�/

29.7 8C, As�/74.4 8C and Af�/81.7 8C and the tern-

ary NiTiCu wires have transformation temperatures,Ms�/46.8 8C, Mf�/38.3 8C, As�/55.6 8C and Af�/

64.2 8C. The martensitic NiTi wires and the stainless

steel wires were not pre-strained. The superelastic wires

K.A. Tsoi et al. / Materials Science and Engineering A342 (2003) 207�/215208

were pre-strained to 0, 1.5 and 3%. The influence of the

wire pre-strain, the wire Vf and the wire position on the

composite’s impact behaviour was investigated.

To allow the SMA wires to be pre-strained andcombined with the pre-preg layers a frame was designed

and made by EPFL, Switzerland. Combs with slots 500

mm apart were situated at either end of the frame. A

continuous SMA wire was then wound between these

two combs and pre-strained to either 0, 1.5 or 3% using

a pre-tensioning knob, which could be held constant

during curing. The wires were then sandwiched between

layers of pre-preg, oriented using a [08,458,908,�/458]2s

layup, where the 0, 45, 90 and �/458 are the ply angles of

the individual pre-preg layers and the 2s indicates that

this layup is repeated twice and then symmetrically

repeated two more times. In total there were 16 pre-preg

layers. The literature, [18], suggests a good resistance

against delamination during impact for this layup. This

laminate offers the opportunity to use a variety of

energies (both low and high) for the impact damagetests. This will also mean there is a greater accuracy due

to less friction from the impact machine. The wires were

aligned along the centre of the plate, covering a width of

16 mm, with a volume fraction of 0.45% (0.5 wires

mm�1), 0.89% (1 wire mm�1) and 1.8% (2 wires mm�1)

and were placed in the centre, off centre at either 1/2, 1/4

or 3/4 of the through thickness of the plates or in the

bottom layer (ie. 15/16 ths). One layer of wires wasembedded in the composites. Fig. 1 shows the dimen-

sions of the specimens used. The SMA composites were

cured at 140 8C for 20 min. The glass fibre pre-preg was

used because of its relatively short curing and easy

handling ability. The resulting plates were, on average,

approximately 2.0 mm thick.

2.2. Impact test set-up

After curing, the specimens were clamped using a

square clamp as seen in Fig. 2. This clamp was used in

order to hold down all sides of the specimen so that

there is less chance of the specimen moving or vibrating

during impact. The type of clamping used can have a

significant effect on the type of impact response of the

specimens, as explained in Ref. [19]. Hence, very

different results would be obtainable depending on the

type of clamping used. The impacting apparatus used

was an in-house built system [20]. A laser detector was

used to record the displacement of the impactor and was

attached to the moving impact frame.

The energies used to impact the specimens were 6, 12

and 18 J. The impact height, H , was determined using

E�/mgH , where E is the energy, m is the mass of the

impact head and g is the acceleration due to gravity (9.8

ms�2). The impact head used was an aluminium pointed

impact head and the total impact frame weighed 1.1 kg.

The height of the impact head used was 0.54 m and the

energies were determined by increasing the weight of the

impact head from 1.1 to 2.2 kg for the 12 J specimens.

For the specimens tested at 18 J the weight of the impact

head was kept at 1.1 kg and the height of the impact

head was placed at 1.65 m. The results shown are an

average of between four and eight specimens of each

type.

Fig. 1. Impact specimen dimensions.

Fig. 2. Impact clamp showing impact specimen.

K.A. Tsoi et al. / Materials Science and Engineering A342 (2003) 207�/215 209

2.3. Analysis techniques

For the impact analysis, a program, ‘Impact Data

Reduction Program’ [20], was used to determine thedifferent impact parameters from the impact curve, by

integration and extrapolation methods.

A C-scan was used to determine the size of the

projected damage area. A C-scan is a non destructive

evaluation technique which uses ultrasound waves to

propagate through a specimen until they reach a barrier

such as a defect or the back of the specimen. These

waves are reflected back to a transducer detector and byanalysing the incoming and outgoing signals, informa-

tion regarding the damaged region can be determined.

The resulting C-scan is a two dimensional representation

of the internal structure of the specimen. A 5 MHz

transducer, from Krautkramer Co. was used for the

scans. A scan area was selected for each specimen,

depending on the size of the damage, and a step size of

150 mm was used.From these techniques the parameters that were

investigated include Ea, the energy absorbed by the

specimen during the impact, Fmax, the maximum force

measured by the load cell on impact, Ad, the projected

delamination area in mm2 measured by the C-scan and

dmin, the lowest point that the impact head reaches

during the impact. This gives a comparison of how far

into the specimen the impact head travels for differenttypes of specimens. The damage depth, which is the

height of the breakage out of the specimen, was also

measured using a micrometer and it is defined as a

measure of the amount of specimen damage, which has

fibre breakage after impact.

It should be noted that techniques that are used to

analyse impact damage for metallic specimens should be

used here with caution. Composites are much morecomplex material systems than metals, and therefore

different parameters are important. Karbhari [21] dis-

cussed the difficulty in determining which parameters

should be used in the impact analysis of composites,

particularly since there are no standards to follow.

3. Results and discussion

An overlay of typical force and displacement impact

curves for the three different impact energies of compo-

site specimens with no wires can be seen in Fig. 3. They

show that the experimental curves differ with increasing

energy levels. The force impact curve shows initially a

bumpy region, A, which is due to the inertial load of the

system [22]. This is the load that the specimen needs to

accelerate from zero velocity to the velocity of theimpact head. This inertial load is present in all of the

impact results. The jagged curves following the initial

inertial load are due to harmonic oscillations of the

specimen once the head has impacted with it. The

specimen is oscillating at its natural frequency.

As the impact energy increases the force curves (Fig.

3(a)) become more jagged and disrupted after the

maximum force. The size of the damage also increases.

For 6 J impacts, the damage is mainly delamination.

With increasing energy the delamination damage area

increases and there is also matrix cracking and fibre

breakage. At 18 J the impact head penetrates the

specimen fully, and the fibre breakage takes on the

shape of a ‘volcano’ in which the fibres break around the

impact tup, i.e. in the shape of the impact tup.Fig. 4 shows the damage for (a) 6 J impact, (b) 12 J

impact and (c) 18 J impact on composite specimens with

no wires (reference specimen).

Fig. 5 shows the impact results (average plus scatter)

for the different wire positions impacted at 6 J with 1

wire mm�1 and 2 wires mm�1. There is a difference of

less than 1% in the energy absorbed and maximum force

during impact for the wires positioned at 1/4, 1/2 and 3/4

when compared to samples with no wires. The wires

positioned along the bottom of the specimen (15/16)

show an improvement in the energy absorbed of around

25 and 19% for 1 wire mm�1 and 2 wires mm�1,

respectively. The Fmax also shows an improvement of

10.4 and 5.8% for 1 wire mm�1 and 2 wires mm�1,

respectively. The wires along the bottom layer produce

the smallest Ea and smallest dmin, which means that the

impact head doesn’t travel as far into the specimen as

the other types of specimens.The projected damage area shows that there is

significantly more damage occurring in the plates which

contain the wires positioned in the centre.

A cross sectional image of a typical specimen with

wires embedded in the centre is shown in Fig. 6(a). It

shows why the plates with the SMA wires situated along

the centre of the plate have more impact damage.

Surrounding the wires is a large amount of the epoxy

matrix but no glass fibres are observed. The reason for

this is that when the wires are placed in the centre, they

are placed between 458 plies. Thus, during curing the

fibres and the wires are in different directions, which

hinder their joining movement, but the epoxy matrix

runs in between them, forming a brittle area. Thus,

during impact, the material is very brittle and suscep-

tible to greater damage. Similar problems have been

observed for the embedment of optical fibres into

composites [23,24]. Fig. 6(b) shows an image of a

specimen where the wires are situated at 1/4 the

thickness. In this case there is a larger number of glass

fibres surrounding the SMA wires.

Fig. 7 shows the projected damage area versus % pre-

strain for a composite with embedded superelastic wires

for an impact of 6 J. Although the wires were embedded

along the centre of the composite it can still be seen that


the projected damage area decreases with increasing pre-

strain.

Fig. 8 shows the impact results for different Vf of

superelastic wires embedded along the bottom of the

specimen impacted with 6, 12 and 18 J. For the 18 J

impacted samples significant differences are visible. Fig.

8(a) shows that the specimen with no wires has the

largest Ea, and the 2 wires mm�1 specimen the smallest.

Fig. 8(b) shows that the 2 wires mm�1 specimen has the

largest Fmax and 0.5 wires mm�1 the smallest. Fig. 8(c)

shows a comparison of the Ad for different Vf of

superelastic wire, for NiTiCu and steel wires. From

this chart it can be seen that for 6 J the Ad is only slightly

smaller for reference specimens when compared to those

with wires. For 12 J the smallest Ad was found for the

reference specimens, 0.5 wires mm�1 and 1 wire mm�1

of superelastic wire. For 18 J impact the best specimens

are the 2 wires mm�1 specimens. The reason that

NiTiCu has a large Ad with big scatter for the 18 J

impact, is that during the impact two types of damage

were observed. Several specimens showed large delami-

nation with no through damage and others almost no

delamination but large through damage and fibre

breakage. The reason that two types of damage were

observed for the same type of specimen is so far, unclear

and further investigation is required. Fig. 8(d) shows

that the 2 wires mm�1 specimen has the smallest dmin. In

general the results for 6 and 12 J shows no significant

differences for Ea, Fmax or dmin. Only at a higher energy

level (18 J) the differences are significant.

Fig. 9(a) shows the damage depth versus wire type for

12 and 18 J and (b) the damage depth versus Ea. There is

a general trend for the damage depth to increase with

increasing absorbed energy (Fig. 9(b)). Only 12 and 18 J

were investigated here, since there was no case of fibre

breakage for the 6 J specimens for wires embedded

along the bottom of the specimen.

Fig. 10 shows the Ad and dmin versus absorbed energy

for the specimens with varying Vf. These curves show

that the damage area increases with absorbed energy.

The increasing absorbed energy needs to be dissipated

by the specimen and usually goes into damaging the

specimen. As the Vf of wires increases the amount of

energy which goes towards damaging the specimen

decreases, since the wires absorb some of that energy.

As can be seen from Fig. 10(a), large delamination area

and large absorbed energy correspond to small Vf of

wires. Fig. 10(b) shows that there is no clear trend

between the Ad and dmin. This suggests that the dmin does

not give any useful information about impact behaviour

for this system.

Fig. 11(a,b), respectively represent the relationship

between Ad versus incident energy and Ea versus

incident energy. These figures show that by increasing

the incident energy of the impact the scatter also

increases. This indicates that for larger impact energies

different types of damage are observed with a larger

Fig. 3. (a) Force vs. time chart and (b) displacement vs. time chart for 6, 12 and 18 J impacts of specimens with no wires.

Fig. 4. Different levels of damage in the composite specimens with no

wires at 18, 12 and 6 J, respectively.


scatter. The PDA slope is defined as the slope

of the damage area versus incident energy and is an

indication of the damage resistance of a material (see

Fig. 11(a)). The IEC slope is the slope of the absorbed

energy vs incident energy and is a measure of the energy

absorption capacity of the material (see Fig. 11(b)). A

high PDA slope is an indication of easier damage

accumulation and a high IEC slope suggests a

greater capacity for internal damping and impact energy

absorption. Fig. 12 shows the impact performance

map, based on the slopes of the two previous

charts.

Fig. 5. (a) Absorbed energy, (b) maximum measured force, (c) projected damage area and (d) minimum measured displacement vs. wire position

impacted at 6J.

Fig. 6. Microscope image of SMA wires embedded between (a) 2�/458 plies and (b) 45 and 08 plies in the SMA composite specimen (the wires are

0.15 mm in diameter).


From Fig. 12 it can be seen that the reference

specimens have a high IEC and PDA slope, indicating

high energy absorption and easy damage accumulation.

Steel and NiTiCu have low IEC and low PDA slopes

indicating that although they have better resistance to

damage accumulation, not a lot of energy is absorbed,

hence these materials are not suitable for high damping

applications. Of the superelastic alloys, the 0.5 wires

mm�1 specimens seem to have good damping proper-

ties, absorb a lot of energy and have a reasonably lowdamage accumulation. In general, all three types of

superelastic wire specimens show good properties. The

choice of wire volume fraction would depend more on

the specific application.

4. Conclusions

This investigation has shown several important as-

pects that need to be considered when looking at the

impact damage behaviour of SMA-composites. Firstly it

was found that Ad decreases with increasing pre-strain.

The position of the wires within a laminate is alsoimportant, in particular between which plies the wires

are embedded. It was found that wires should be

embedded between 08 plies and any other ply, in order

to incorporate them into the matrix, leaving no brittle

areas. Also, embedding wires in the lower half of the

Fig. 7. Projected damage area vs. % pre-strain.

Fig. 8. (a) Absorbed energy, (b) maximum measured force, (c) projected damage area and (d) minimum measured displacement vs. wire type for 18,

12 and 6 J impacts where the wires are embedded along the bottom of the SMA-composite specimen.


specimen, preferably along the bottom layer, improves

the resistance, in particular, to fibre breakage damage.

The wire density also plays an important role and it

was shown that, particularly for higher energy impacts

of around 18 J, 1.8% Vf of wires produces the best

results and are comparable to the results found by

previous researchers [16]. For the lower impact energies

(6 and 12 J), the size of damage of SMA-composites,

Fig. 9. Damage depth vs. (a) incident energy and (b) absorbed energy for different specimen types where the wires are embedded along the bottom of

the SMA-composite specimen.

Fig. 10. (a) Projected damage area and (b) minimum measured displacement vs. absorbed energy for different Vf of wires.

Fig. 11. (a) Projected damage area vs. incident energy, (b) absorbed energy vs. incident energy.


compared with reference specimens, was equivalent and

differs from previously seen results [16]. These discre-

pancies may be due to the differing layup of the

composites. Also due to the limited amount of wire

compared to the total volume of the SMA-compositethe effect of the wire on the impact behaviour is limited.

Composites are complex materials with complex

behaviours, so by embedding SMA wires into compo-

sites many factors need to be considered. Further

investigations into the effects of increasing the Vf of

the SMA wires in the composites would be useful in

determining the optimal amount of SMA required in

order to decrease impact damage.

Acknowledgements

This research was completed in the framework of the

ADAPT project that was funded by the European

Commission, in the Industrial and Materials Technolo-

gies research and technological programme. Kelly Tsoiis an International Scholar from the School of Aero-

space, Mechanical and Mechatronic Engineering of the

University of Sydney and acknowledges Dr. Stephen C.

Galea for his generous support during this research, the

financial support of the Defence Science and Technol-

ogy Organisation of Australia and Zonta International

through the Amelia Earhart Fellowship Award. The

authors would like to acknowledge Kris Van de Staeyand Pieter Alles for their help in the preparation of the

specimens, Johan Vanhulst for his help with the C-scans,

and Jo Marien and Hermawan Judawisastra for impact

advice.

References

[1] J.E. Bidaux, J.A.E. Manson, R. Gotthard, Mater. Res. Soc.

Symp. Proceedings, vol. 459, 1997, pp. 107�/117.

[2] R. Gotthardt, J.-E. Bidaux, in: K. Inue (Ed.), International

Conference on Displacive Phase Transformations and their

Application in Material Engineering, TMS, Warrendale, PA,

1988, pp. 157�/166.

[3] J.-E. Bidaux, J.-A.E. Manson, R. Gotthardt, Third ICIM/

ECSSM ’96, Lyon, 1996, pp. 517�/522.

[4] D.A. Hebda, M.E. Whitlock, J.B. Ditman, S.R. White, J. Intell.

Mater. Syst. Struct. 6 (1995) 220.

[5] C.M. Friend, C.R.D. Mattey, in: G.R. Tomlinson, W.A. Bul-

lough (Eds.), 4th ESSM and 2nd MIMR Conference, Harrogate,

6�/8 July, 1998, Institute of Physics, 1998, p. 107.

[6] Y.J. Zheng, J. Schrooten, K.A. Tsoi, P. Sittner, Exp. Mech. (2001)

submitted for publication.

[7] K.A. Tsoi, R. Stalmans, J. Schrooten, Acta Mater. (2001) in

press.

[8] R. Stalmans, K.A. Tsoi, J Schrooten, in: P.F. Gobin, C.M. Friend

(Eds.), Fifth European Conference on Smart Structures and

Materials, Glasgow, Scotland, 22�/24 May, 2000, Proceedings of

SPIE, vol. 4073, 2000, p. 88.

[9] J. Schrooten, K.A. Tsoi, R. Stalmans, Y.J. Zheng, P. Sittner, in:

A.R. Wilson, H. Asanuma (Eds.), Proceedings of SPIE, Smart

Materials and MEMS, 13�/15 December, Melbourne, Australia,

vol. 4234, 2000, pp. 114�/124.

[10] J.A. Balta, V. Michaud, M. Parlinska, R. Gotthardt, J.A.

Manson, in: C. Lynch (Ed.), Proceedings of SPIE; Smart

Materials and Structures; Active Materials; Behaviour and

Mechanics, 4�/8 March, Newport Beach, CA, vol. 4333, 2001,

pp. 377�/386.

[11] J.A. Balta, V. Michaud, M. Parlinska, R. Gotthardt, J.A Manson,

Structural Development upon Polymer Processing: Physical

Aspects, 24�/28 October, Guimaraes, Portugal, European Physi-

cal Society, 2000, pp. 33�/34.

[12] J.A. Balta, V. Michaud, M. Parlinska, R. Gotthardt, J.A Manson,

Materials for Smart Systems III, 30 November�/12 December,

1999, Boston, MA, Materials Research Society, vol. 604, 2000,

pp. 141�/146.

[13] G.C. Psarras, J. Parthenios, C. Galiotis, J. Mater. Sci. 36 (2001) 1.

[14] J. Parthenios, G.C. Psarras, C. Galiotis, Composites part A:

applied science and manufacturing (2001) 32 (2001) 1735-1747.

[15] A.A. Baker, R. Jone, R.J. Callinan, Composite Struct. 4 (1985)

15.

[16] J.S.N. Paine, C.A. Rogers, J. Intell. Mater. Syst. Struct. 5 (1994)

530.

[17] K.N. Melton, in: T.W. Duerig, K.N. Melton, D. Stockel, C.M.

Wayman (Eds.), Engineering Aspects of Shape Memory Alloys,

Butterworth�/Heinemann, London, 1990, p. 21.

[18] G. Clark, Composites 20 (3) (1989) 209.

[19] S.-S. Pang, S. Krishnappa, C. Yang, Impact, Waves and Fracture,

American Society of Mechanical Engineers, Applied Mechanics

Division, AMD, vol. 205, ASME, New York, 1995, pp. 467�/480.

[20] D. Philips, Characterisation and development of 3D-knitted

composites, PhD thesis, Department of Metallurgy and Materials

Engineering, Katholieke Universiteit Leuven, September 1999.

[21] V.M. Karbhari, J. Mater. Sci. 32 (1997) 4159.

[22] M.C. Cheresh, S. McMichael, in: S.L. Kessler, G.C. Adams, S.B.

Driscoll, D.R. Ireland (Eds.), Instrumented Impact Testing of

Plastics and Composite Materials, vols. ASTM STP-936, Amer-

ican Society for Testing and Materials, Philadelphia, PA, 1987, p.

9.

[23] L.G. Leka, E. Bayo, J. Composites Technol. Res. 11 (3) (1989)

106.

[24] A. Salehi, A. Tay, D.A. Wilson, D.G. Smith, Design and

Manufacturing of Advanced Composites Conference Proceed-

ings, 5th Annual ASM/ESD Advanced Composite Conference,

25�/28 September, Michigan, USA, 1989, pp. 11�/19.

Fig. 12. Impact performance map.


impact damage behaviour of shape memory alloy composites

Documents