Evaluation of Low Velocity Impact Response of Composite Plates Embedded with SMA

Mechanics, Materials Science & Engineering, September 2017 – ISSN 2412-5954

Evaluation of Low Velocity Impact Response of Composite Plates Embedded with SMA wires- An Analytical and Numerical Approach 1

Buddhi Arachchige1, a 1 – Cranfield University, Bedford, United Kingdom a – B.M.Archchige@cranfield.ac.uk DOI 10.2412/mmse.43.56.827 provided by Seo4U.link

Keywords: impact, shape memory alloys, recovery stress, smart composites, finite element.

ABSTRACT. This paper involves an analytical and numerical study to analyse the effect of SMA wires on the low velocity impact response of composite plates. First order shear deformation theory and a two-degree of freedom springmass system derived functions for the contact force history, which was used to study the impact response of SMA embedded graphite/epoxy flat plates. Numerical modelling in LSDYNA is used to validate the analytical model and studies were performed analytically and numerically to analyse the effect of SMA volume fraction and positioning on the impact performance. Results proved that SMA wires improved impact damage resistance.

Introduction. Composite materials are widely used for various applications in aerospace, automotive, marine industries due to their attractive properties such as been lightweight, high strength and corrosion resistivity [1-4]. However, composites are susceptible to impact damage due to lack of through the thickness reinforcement and weak interfaces. Delaminations and matrix cracking are the dominant failure modes in a low velocity impact event and thus reduces the structural integrity of a composite material [5-7]. Therefore, improving the damage resistance of composites is vital and embedding SMA wires into a composite laminates is considered to be an effective method to increase the damage tolerance of composite structures [8].

The effect of embedding SMA wires into composites on the low velocity impact behaviour have been a widely popular topic among researchers [9-14]. Lei et al. [9] investigated the macroscopic mechanical behaviour of SMA embedded hybrid composites. Results proved that ultimate strength of the composite increased with the number of embedded SMA fibre and reduction in the rupture elongation. Aurrekoetxea et al. [10] studied the effect of super-elastic shape memory alloy wires on the impact behaviour of woven carbon fabric composites. Their results proved that SMA wires improved the energy absorption capability on hybrid composites.

Kang and Kim [11] experimentally investigated the effect of SMA wires on low velocity impact damage behaviour of glass/epoxy laminates. The main conclusions drawn from their study were that impact damage was mainly in the form of delaminations and impact response was affected by both the SMA wires and temperature. Raghavan et al. [12] evaluated the capability of shape memory alloy fibres to improve damping capacity and toughness of a thermoset polymer matrix. Reinforcement of the polymer with SMA fibres resulted in an improvement in damping, tensile and impact properties.

Lau et al. [13] studied the low velocity impact behaviour of shape memory alloy (SMA) stitched composite plates. The analytical study based on quasi-static energy balance equation derived that the delamination energy for stitched glass/epoxy plates were smaller compared to unstitched composite plates and that the number of matrix cracks were less for the stitched plates. Tensile modulus of the stitched plates were also greater proving that impact resistance could be improved by the use of SMAs in composites. Tsoi et al. [14] experimentally analysed the effect of shape memory alloys on impact 1

© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

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Mechanics, Materials Science & Engineering, September 2017 – ISSN 2412-5954

resistance of glass/epoxy composites. They demonstrated that placement of SMA wires are crucial and positioning them closer to the bottom layer significantly improved resistance to fibre breakage.

It was also shown that higher volume fraction of the wires improved impact damage resistance. Paine and Rogers [15] proved that SMA wires were able to reduce composite ply-delamination by 25% by embedding them within graphite/bismaleimide hybridized composite. Khalili and Ardali [16] developed an analytical model to study the low velocity impact response of doubly curved composite plates embedded with SMA wires. They used the first order shear deformation theory and a twodegree of freedom spring-mass model to analyse effect of impact parameters and shape memory wires on the impact response, and proved that structural stiffness is increased through the use of SMAs in composites.

This paper focuses on developing an analytical model to analyse the low velocity impact response of flat composite plates embedded with SMA wires. The main highlight of this research is the development of a finite element model in LS-DYNA, which was identified as the research gap. To the authors’ present knowledge, this is the first finite element model to evaluate the impact response of SMA embedded composite plates.

Fig. 1. Composite plate embedded with SMA wires.

Analytical Modelling. The analytical modelling consists of a square plate 100mm×100mm with a total thickness of 0.85 mm. The stacking sequence of the composite plates were [45°/-45°/90°/0°] and the SMA wires were aligned along the centre of the plate, covering a 20 mm width. The diameter of SMA wires were 0.2 mm. A spherical steel impactor with diameter 15.35 mm and mass of 2.38 kg was impacted at the centre.

First order shear deformation theory presents the displacement field as: đ?‘˘(đ?œ 1 , đ?œ 2 , đ?œ , đ?‘Ą) = đ?‘˘0 (đ?œ 1 , đ?œ 2 , đ?‘Ą) + đ?œ đ?œ‘1 (đ?œ 1 , đ?œ 2 , đ?‘Ą)

(1)

đ?‘Ł(đ?œ 1 , đ?œ 2 , đ?œ , đ?‘Ą) = đ?‘Ł0 (đ?œ 1 , đ?œ 2 , đ?‘Ą) + đ?œ đ?œ‘2 (đ?œ 1 , đ?œ 2 , đ?‘Ą)

(2)

đ?‘¤(đ?œ 1 , đ?œ 2 , đ?œ , đ?‘Ą) = đ?‘¤0 (đ?œ 1 , đ?œ 2 , 0)

(3)

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Mechanics, Materials Science & Engineering, September 2017 – ISSN 2412-5954

where 𝑢0 , 𝑣0 and 𝑤0 represents the displacements of a point (𝜁1 , 𝜁2 , 0) on the mid-surface of the shell; 𝜑1 and 𝜑2 are the rotations.

The equations of motion for a symmetric cross-ply composite shell considering in-plane initial stress resultants 𝑁𝑥𝑖 and 𝑁𝑦𝑖 are expressed as [16]: 𝜕2 𝑢

1 𝜕𝑤0

𝐴11 ( 𝜕𝑥 20 + 𝑅 𝜕 2 𝜑2

+ 𝜕𝑥

1 𝜕𝑥2

1

1

1

𝜕2 𝑢0

+𝑅

2

𝜕𝑥2

1 𝜕𝑤0

) + 𝑘𝑠ℎ 𝐴55 ( 𝑅 + 𝑅

𝐴12 (𝜕𝑥 1 𝜕𝑤0

𝜕𝑥1

𝜑1

𝜕2 𝑣0

) + 𝐴12 (𝜕𝑥

1 𝜕𝑤0

+𝑅

1 𝜕𝑥2

1

𝑣0

2

𝜕2 𝑤

− 𝑅2 ) +

𝜕𝑣0

𝑤0

2

2

1

𝜕𝑥1

𝜕2 𝑣

2

2

𝜕𝜑2

+ 𝜕𝑥 2 ) +

1 𝜕𝑥2

𝜕𝜑

1

1 𝜕𝑢0

1

𝜕𝑢0

𝜕𝑥1 𝑤0

1

𝜕2 𝑣0

) + 𝐴66 (𝜕𝑥

𝜕𝑥1 𝑖 𝑁11 𝜕𝑤0

+

1 𝜕𝑤0

1

𝜕𝑤 𝑖 + 𝜕𝑥 [𝑁22 ( 𝜕𝑥 0 2 2

2

1

𝑣0

− 𝑅 )] + 𝑞 = 𝐼0

𝜕2 𝜑

+𝐼1

𝜕2 𝑢0 𝜕𝑡 2

𝜕2 𝑤

𝜕𝑣0

2 𝑤0

2

2

𝜕 2 𝜑1

+𝐼1

𝜕𝑡 2

𝜕2 𝑢

𝜕2 𝑢0

𝑣0

− 𝑅 ) = 𝐼0 2

𝜕𝜑

− 𝐼1

𝜕2 𝜑1 𝜕𝑡 2

2

=0

𝜑

1 𝜕𝑥2 𝜕2 𝑣0 𝜕𝑡 2

) + [𝑘𝑠ℎ 𝐴44 ( 𝑅 2 + 2

𝜕2 𝜑2

+

(5)

𝜕𝑡 2

1 𝜕𝑢 ) − 𝑅 {𝐴11 (𝜕𝑥0 𝜕𝑥2 1 1 𝜕 𝜕𝑤0 𝑢0 𝑖 [𝑁11 ( 𝜕𝑥 − 𝑅 )] + 𝜕𝑥1 1 1 2

(4)

1 𝜕𝑣0 2

𝑤

+ 𝑅0) + 1

(6)

𝜕𝑡 2

𝜕 2 𝜑2

1 𝜕𝑥2

) + 𝐷66 (𝜕𝑥

1 𝜕𝑥2

+

𝜕 2 𝜑1 𝜕𝑥22

𝜕𝑤

𝑢

) − [𝑘𝑠ℎ 𝐴55 (𝜑1 + 𝜕𝑥 0 − 𝑅0 )] = 𝐼2 1

1

𝜕 2 𝜑1 𝜕𝑡 2

+

(7)

𝐷66 (𝜕𝑥

𝜕2 𝑣0 𝜕𝑡 2

1

𝜕 2 𝜑2

1

1

𝜕2 𝜑

) + 𝑐0 𝐷66 ( 𝜕𝑥 21 +

) + 𝑘𝑠ℎ 𝐴44 ( 𝜕𝑥 20 + 𝜕𝑥 2 − 𝑅

𝜕2 𝑤0

2

𝐷11 ( 𝜕𝑥 21 ) + 𝐷12 (𝜕𝑥

𝜕𝑥22

𝜕2 𝑢0

1

𝐴12 (𝜕𝑥 + 𝑅 )} + 𝑅 {𝐴12 (𝜕𝑥 + 𝑅 ) + 𝐴22 (𝜕𝑥 + 𝑅 )} + 𝜕

𝜕 2 𝑢0

) + 𝐴66 ( 𝜕𝑥 20 + 𝜕𝑥

𝜕𝑥2 𝑖 𝑖 𝜕𝑁22 𝑁22 𝜕𝑤 + ( 0 𝜕𝑥2 𝑅2 𝜕𝑥2 2

1 𝜕𝑥2

𝑢0

+

( 𝜕𝑥 − 𝑅 ) − 𝐼0

𝑅1

) + 𝐴22 ( 𝜕𝑥 20 + 𝑅

𝑘𝑠ℎ 𝐴55 ( 𝜕𝑥 20 + 𝜕𝑥 1 − 𝑅 1

𝑖 𝜕𝑁11

1

𝜕𝑥2 𝜕𝜑1

− 𝑅2 )] − 𝑐0 𝐷66 (𝜕𝑥

1 𝜕𝑥2

𝑢0

𝜕𝑥1

1

1 𝜕𝑤0

+𝑅

1 𝜕𝑥2

+

𝜕2 𝜑2 𝜕𝑥12

𝜕 2 𝜑1

) + 𝐷12 (𝜕𝑥

1 𝜕𝑥2

𝜕2 𝜑

𝜕𝑤

𝑣

) + 𝐷22 ( 𝜕𝑥 22 ) − [𝑘𝑠ℎ 𝐴44 (𝜑2 + 𝜕𝑥 0 − 𝑅0 )] = 𝐼2 2

2

2

𝜕 2 𝜑2 𝜕𝑡 2

+ (8)

For a flat rectangular plate 𝑅1 = 𝑅2 = ∞ Stress-strain relationship for a laminate composite embedded with SMA wires are expressed as: 𝜎1 𝑄11 𝜎 { 2 } = (𝑄12 𝜎3 0

𝑄12 𝑄22 0

𝑚 𝜀1 𝑄11 0 𝜎𝑟 𝑚 0 ) { 𝜀2 } + { 0 } 𝑘𝑠 − (𝑄12 0 𝑄66 𝛾12 0

𝜏23 𝑄 [𝜏 ] = ( 44 0 13 𝐴𝑖𝑗 𝑁 { }=( 𝐵𝑖𝑗 𝑀

0 𝛾23 )[ ] 𝑄55 𝛾13 𝑖 𝐵𝑖𝑗 𝜀 0 ) { 1} + {𝑁 𝑖 } 𝐷𝑖𝑗 𝜀 𝑀

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𝑚 𝑄12 𝑚 𝑄22 0

0 𝛼1𝑐 0 ) {𝛼2𝑐 } 𝑘𝑐 ∆𝑇 𝑚 𝑄66 0

(9)

(10)

(11)

Mechanics, Materials Science & Engineering, September 2017 – ISSN 2412-5954 đ?‘&#x; đ?‘‡ đ?‘– { đ?‘ đ?‘– } = { đ?‘ đ?‘&#x; − đ?‘ đ?‘‡ } ; đ?‘–, đ?‘— = 1,2,6 đ?‘€ −đ?‘€ đ?‘€

(12)

{đ?‘†} = [đ?‘˜đ?‘ â„Ž đ??´đ?‘–đ?‘— ]{đ?œ€ 0 }; đ?‘–, đ?‘— = 4,5

(13)

đ?‘š đ?‘? đ?‘š đ?‘? )đ?‘˜ đ?œŽđ?‘&#x; đ?‘˜đ?‘ đ?‘Ľ â„Žđ?‘Ľ − (đ?‘„11 đ?›ź1 + đ?‘„12 đ?›źđ?‘Ą đ?‘?đ?‘Ľ â„Žđ?‘Ľ ∆đ?‘‡ đ?‘– đ?‘š đ?‘? đ?‘š đ?‘ = {đ?œŽđ?‘&#x; đ?‘˜đ?‘ đ?‘Ś â„Žđ?‘Ś − (đ?‘„12 đ?›ź1 + đ?‘„22 đ?›źđ?‘Ąđ?‘? )đ?‘˜đ?‘?đ?‘Ś â„Žđ?‘Ś ∆đ?‘‡} 0

(14)

In this particular problem, the SMA wires are placed in x-direction. Therefore, đ?‘˜đ?‘ đ?‘Ś – is zero since no wires are placed in y-direction. Double Fourier series are used to obtain solutions to the dynamic problem based on expansion of loads, displacement and rotation functions. Deflections and rotations of a flat composite plate using Double Fourier series are expressed as [17]: đ?‘šđ?œ‹đ?‘Ľ1

∞ đ?‘˘0 (đ?‘Ľ1 , đ?‘Ľ2 , đ?‘Ą) = ∑∞ đ?‘›=1 ∑đ?‘š=1 đ?‘ˆđ?‘šđ?‘› (đ?‘Ą)đ?‘?đ?‘œđ?‘

∞ đ?‘Ł0 (đ?‘Ľ1 , đ?‘Ľ2 , đ?‘Ą) = ∑∞ đ?‘›=1 ∑đ?‘š=1 đ?‘‰đ?‘šđ?‘› (đ?‘Ą)đ?‘ đ?‘–đ?‘›

đ?‘šđ?œ‹đ?‘Ľ1 đ?‘Ž

đ?‘ đ?‘–đ?‘›

∞ đ?‘¤0 (đ?‘Ľ1 , đ?‘Ľ2 , đ?‘Ą) = ∑∞ đ?‘›=1 ∑đ?‘š=1 đ?‘Šđ?‘šđ?‘› (đ?‘Ą)đ?‘ đ?‘–đ?‘›

đ?‘šđ?œ‹đ?‘Ľ1

∞ đ?œ‘1 (đ?‘Ľ1 , đ?‘Ľ2 , đ?‘Ą) = ∑∞ đ?‘›=1 ∑đ?‘š=1 đ?‘‹đ?‘šđ?‘› (đ?‘Ą)đ?‘?đ?‘œđ?‘

đ?‘šđ?œ‹đ?‘Ľ1

∞ đ?œ‘2 (đ?‘Ľ1 , đ?‘Ľ2 , đ?‘Ą) = ∑∞ đ?‘›=1 ∑đ?‘š=1 đ?‘Œđ?‘šđ?‘› (đ?‘Ą)đ?‘ đ?‘–đ?‘›

đ?‘Ž

đ?‘Ž đ?‘šđ?œ‹đ?‘Ľ1 đ?‘Ž

đ?‘›đ?œ‹đ?‘Ľ2

đ?‘ đ?‘–đ?‘›

đ?‘Ž

đ?‘?

đ?‘›đ?œ‹đ?‘Ľ2 đ?‘?

đ?‘ đ?‘–đ?‘›

đ?‘›đ?œ‹đ?‘Ľ2

đ?‘ đ?‘–đ?‘›

đ?‘›đ?œ‹đ?‘Ľ2

đ?‘?đ?‘œđ?‘

đ?‘?

đ?‘? đ?‘›đ?œ‹đ?‘Ľ2 đ?‘?

(15)

(16)

(17)

(18) (19)

The terms of the Fourier series can be expressed as: ∞ đ?‘žđ?‘› (đ?‘Ľ1 , đ?‘Ľ2 , đ?‘Ą) = ∑∞ đ?‘›=1 ∑đ?‘š=1 đ?‘„đ?‘šđ?‘› (đ?‘Ą)đ?‘ đ?‘–đ?‘›

đ?‘šđ?œ‹đ?‘Ľ1 đ?‘Ž

đ?‘ đ?‘–đ?‘›

đ?‘›đ?œ‹đ?‘Ľ2 đ?‘?

(20)

Impact Model. A two degree of freedom system consisting of the plate and impactor is considered as shown in Figure 2.

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Mechanics, Materials Science & Engineering, September 2017 – ISSN 2412-5954

Fig. 2. Two degree of freedom spring-mass model.

The contact force is related to contact deformation by [17]: đ??šđ?‘?∗ (đ?‘Ą) = đ??ž2∗ đ?œ•

(21)

The equations of motion for the two degree of freedom system is: đ?‘š1 đ?‘§Ěˆ1 = −đ?‘˜1 đ?‘§1 − đ?‘˜2 (đ?‘§1 − đ?‘§2 )

(22)

đ?‘š2 đ?‘§Ěˆ2 = −đ?‘˜2 (đ?‘§2 − đ?‘§1 )

(23)

The analytical force-function is defined as [17]: đ??šđ?‘?∗ (đ?‘Ą) = đ??ž2∗ [đ??´1 (đ??ś1 − 1)đ?‘ đ?‘–đ?‘›đ?œ”1 đ?‘Ą + đ??´2 (đ??ś2 − 1)đ?‘ đ?‘–đ?‘›đ?œ”2 đ?‘Ą]

(24)

The natural frequency of the composite plate is expressed as: [16] 2 đ?œ”đ?‘šđ?‘› =

−(đ?‘?13 đ??žđ?‘ˆ +đ?‘?23 đ??žđ?‘‰ +đ?‘?33 +đ?‘?34 đ??žđ?‘Ľ +đ?‘?35 đ??žđ?‘Œ ) đ?œŒâ„Ž

(25)

Model validation. The analytical model is validated with available experimental work on impact response of SMA embedded flat composite plates. Material properties of graphite/epoxy CU-125NS are presented in Table 1 and material properties of SE 508 SMA wire in Table 2. Stress strain behaviour is depicted in Figure 3.

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Mechanics, Materials Science & Engineering, September 2017 – ISSN 2412-5954

Table 1. Properties of plate [18].

E1

135.4GPa

E2

9.6GPa

G12

4.8GPa

đ?œ?

0.31

Table 1. Properties of SMA wires [18].

Martensite

Austenite

Transfer coefficient

4.6MPa/°C

6.4MPa/°C

Elastic modulus

17.0GPa

40.1GPa

Failure stress

1179MPa

1434MPa

Failure strain

14.9%

14.4%

Fig. 3. Stress-strain behaviour of SE508 wire.

Numerical modelling. In this section, a finite element model in LS-DYNA is developed. Material Model 54 with Chang-Chang failure criteria in LSDYNA is used to model the composite failure in the plate. Four failure modes; tensile fibre failure, compressive fibre failure, tensile matrix failure and compressive matrix failure are incorporated in this model. The size of the composite plate was 100 × 100��2 with a 0.85mm thickness. The composite plates were meshed using 1 × ��2 shell elements. Integration points were used in defining the layers. Similarly, to the experimental study [14], SMA wires of 0.2mm diameter were spaced equally within a width of 20mm. They were embedded in between the 8 layers (i.e. at 4 layers from the bottom layer) corresponding to a stacking sequence of [45°/-45°/90°/0°]s as shown in Figure 4. Material model 30 is used to model the shape memory wires and material model 20 was used for the impactor. The mass of the impactor was 2.38kg with an impact velocity of 4.4m/s. An impact model for a flat plate was also developed to compare the performance of the SMA embedded composite.

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Mechanics, Materials Science & Engineering, September 2017 – ISSN 2412-5954

a)

b)

Fig. 4. Finite element model (SMA Embedded plate) (a) impact model (b) placement of SMA wires.

a)

b)

c) Fig. 5. Finite element models (a) Conventional plate (without SMA) (b) von Misses stress in SMA plate (c) bending of SMA wires.

Analysis and Results.

Analytical Model. The force function in equation 24 is used to analyse the effect of SMA wires on impact resistance of composites. Results were compared with that of a flat composite plate with the same material and dimensions under same impact loading conditions. Results proved that the impact performance of the composite plate embedded with SMAs are 7% higher than the conventional plate.

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Mechanics, Materials Science & Engineering, September 2017 – ISSN 2412-5954

Fig. 6. Analytical model contact force history.

The effect of the fibre volume fraction of SMA wires are also studied. The volume fraction đ?‘˜đ?‘ is varied from 0 to 0.3. The results proves that an increase in SMA volume fraction from 0 to 0.1 causes the maximum contact force to increase by 6%, proving that the volume fraction is a vital factor in improving the impact resistance of SMA embedded plates.

Fig. 7. Effect of SMA volume fraction on contact force history.

Validation. The numerical model was validated with the analytical model developed. Contact force history comparison is shown in Figure 8. These results proved that the numerical model closely matched with the analytical model and experimental work done in literature [18]. The difference in maximum contact force of the numerical model was less than 5% when compared to the analytical and experimental models.

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Mechanics, Materials Science & Engineering, September 2017 – ISSN 2412-5954

Fig. 8. Contact force history comparison.

A comparison is made to analyse the effect of the SMA wires on the impact response and deflection histories. Results of the SMA embedded plate were compared with the conventional plate to compare the performance under impact loading. Until the fracture point at around 3-4ms, there was not any different in the contact force histories between the two plates. This proved that up-to that point, the SMA wires had negligible effect. However, after the composite laminates fractured, it was observed that the contact force of SMA embedded plates were higher than the conventional plate, thus implying that SMA wires resist higher impact loads after fracture and that they prevent damage propagation of the laminates. The deflection history results showed that SMA embedded plates deflected less than the conventional plates. Deflection recovery was also higher and it almost recovered up-to its original shape as shown in Figure 10. This was due to the smaller damage regions of the SMA embedded plate caused by higher impact resistance and recovery stress generated by the SMA wires. FE simulations showed that this stress recovery caused the SMA plate to bounce the impactor.

Fig. 9. Contact force history (Conventional and SMA embedded plate).

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Mechanics, Materials Science & Engineering, September 2017 – ISSN 2412-5954

Fig. 10. Deflection history (Conventional and SMA embedded plate).

Parametric Study. A parametric study is carried out to analyse the effect of the positions of SMA wires on improving impact damage resistance of composite laminates. Four different locations were analysed at 1/6, 3/6, 4/6, 5/6 positions through the plate thickness, corresponding to 1/6 been SMA placement is on the upper layers, 3/6 been on the mid surface and 5/6 on the bottom surface. FE models developed to study this placement effect are shown in Figure 11. a)

b)

c)

d)

Fig. 11. Positioning of SMA wires (a) 1/6, (b) 3/6, (c) 4/6, (d) 5/6.

Contact force history plot is shown in Figure 9 and it is clearly seen that when SMAs are embedded in the bottom layer (5/6), the plate resists a higher impact force. Moving the wires from top layer (1/6) to the bottom layer (5/6) increased the maximum contact force by 13%, thus proving the effectiveness of SMA placement in laminate design to withstand impact loading.

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Fig. 12. Effect of SMA wire placement on contact force history.

Summary. This paper presented an analytical and numerical model to analyse the effect of SMA wires on the low velocity impact performance of flat composite laminates. First order shear deformation theory was used in deriving the contact force function, and natural frequency of the plate was determined by incorporating the effect of SMA volume fractions, recovery stresses and thermal expansion coefficients. Contact force history results proved that the SMA embedded plate resisted 7% higher impact loads than the conventional plate. Studying the effect of SMA volume fraction suggested that the plate is able to sustain 6% higher loads than the conventional plate when volume fraction increases from 0 to 0.1. A major highlight of the present paper, which is the development of a finite element model in LSDYNA, validated the analytical model results and experimental work on SMA embedded plates. Finally, an analysis was performed to analyse the effect of SMA wire placement in the laminate, and results proved that placing SMA wires in the bottom layer increases the impact resistance by 13%.

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