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Impact and post impact behavior of layer fabric composites
Composite Structures 94 (2012) 2809–2818
Contents lists available at SciVerse ScienceDirect
Composite Structures journal homepage: www.elsevier.com/locate/compstruct
Impact and post impact behavior of layer fabric composites Mehmet Aktasß a,⇑, H. Ersen Balcıog˘lu a, Alaattin Aktasß b, Erkan Türker c, M. Emin Deniz d a
Usak University, Department of Mechanical Engineering, 64200 Usak, Turkey Istanbul University, Department of Mechanical Engineering, 34320 Istanbul, Turkey c Usak University, Department of Textile Engineering, 64200 Usak, Turkey d Harran University, Department of Mechanical Engineering, 63190 Sanliurfa, Turkey b
a r t i c l e
i n f o
Article history: Available online 23 April 2012 Keywords: Impact behavior Post-impact behavior Plain weave layer fabric Double layer fabric Triple layer fabric CAI strength
a b s t r a c t In this study, the effect of impact and post impact behavior of E-glass/epoxy composite plates having different layer fabrics were investigated by considering energy profile diagram and the related load– deflection curves. Different impact energies (5 J–60 J)were subjected to the plates consisting of eight layers of plain weave (1D), double (2D) and triple (3D) layer fabrics. The impact tests were continued until complete perforation of layer fabrics. The damage modes and damage processes of layer fabrics under varied impact energies were also discussed. At the end of the impact tests, the damaged samples were mounted into a compression apparatus to determine the Compression After Impact (CAI) strength of layer fabric samples. The results of these impact and post impact tests showed that contact force occurring between the impactor and the composite specimen increased and the CAI strength reduced by increasing the impact energy. The objective of this study was to determine the perforation threshold of E-glass/epoxy composite plates having different layer fabrics as plain weave (1D), double (2D), and triple (3D) layer fabrics. Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction Composite materials have excellent mechanical properties combined with low density. Therefore, composite materials have been used in a wide range of applications as aerospace, automotive, defense, and sport industries. In spite of having superior advantage, laminated composites are susceptible to damages under transverse impacts. Hence, the impact behavior of laminated composites has been an important research area for a long time [1–4]. Mathivanan and Jerald [5] have carried out an experimental investigation for concerning the low-velocity impact behavior of woven glass/epoxy composite laminates. The impact tests were conducted to characterize the type and extent of the damage observed in laminate of different thicknesses (2, 4, and 6 mm) subjected to different impact velocities. At the end of the tests, they found that the glass/epoxy composites have no sensitivity to the strain rate effect. Baucom et al. [6] have investigated damage accumulation in 2D and 3D woven glass/epoxy composite laminated plates under repeated impact loading. These plates contained different fabric architectures, fiber-volume fraction, and thickness. The woven composites were subjected to multiple impacts of 44 J at 4 m/s until perforation occurred. According to the test results, in 2D plates, the energy
⇑ Corresponding author. Tel.: +90 276 2212136/2727; fax: +90 276 2212137. E-mail address: [email protected] (M. Aktasß). 0263-8223/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.compstruct.2012.04.008
dissipated on the first strike ranged from about 21 J to 24 J. For the 3D plates, however, the initial energy dissipation was 25 J. Shim and Yang [7] examined the residual mechanical properties of crowfoot-weave carbon/epoxy laminates subjected to lowvelocity impact loading. It was found that the residual strength and stiffness of the impacted laminates decreased with increasing impact damage area. Hosur et al. [8] determined the impact response of four different combinations of hybrid laminates which have twill weave carbon fabric and plain weave S2-glass fabric using VARTM process with SC-15 epoxy resin system. The hybrid laminates were subjected to low-velocity impact loading at four energy levels of 10, 20, 30, and 40 J. Dehkordi et al. [9] investigated low-velocity impact behavior of homogenous and hybrid composite laminates reinforced by basalt–nylon intra-ply fabrics. They selected five different types of woven fabrics and five different volume fractions of nylon (0%, 25%, 33.3%, 50% and 100%). The effect of nylon/basalt fiber content on the maximum force, maximum deflection, residual deflection, total absorbed energy, elastic energy, size and type of damage were studied at several impact energies (16, 30 and 40 J). The results showed that the impact performance of these composites was significantly affected by the nylon/basalt fiber content. As a result, the elastic and total absorbed energy increased with the nylon/basalt fiber contents by increasing the impact energy. Sayer et al. [10] studied the impact behavior of hybrid composite plates. Impact tests were performed on two types of hybrid composite plates
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(glass–carbon/epoxy) until complete perforation of the specimens. The failure mechanisms of damaged specimens for different impact energies were evaluated by comparing the load–deflection curves and images of the damaged samples taken from impacted sides and non-impacted sides. The test results revealed that the perforation threshold of the hybrid composite with carbon facesheet was found approximately 30% higher than the hybrid composite with glass facesheet. Yin et al. [11] performed an experimental study for healing of impact damage in woven glass/epoxy composites with crack by pre-dispersing a novel repair system in the matrix. CAI tests were also conducted to evaluate mechanical performance of the lami-
nates before and after the crack healing. The experimental results indicated that the healing agent worked in repairing the matrix cracks generated by impact. Icten et al. [2] investigated impact behavior of laminated glass/epoxy composites under different impact energies ranging from 5 J to 70 J at low temperatures of 20oC, 20oC and 60oC. In this study, the maximum contact force, maximum deflection, maximum contact time and absorbed energy versus impact energy were determined. In order to determine the energy absorbing capability, the energy profiling method was utilized. The results showed that the ambient temperature highly affected the impact behavior of the composite materials and the damage area increased with the increasing impact energy.
Fig. 1. The schematic illustration of the plain weave (1D) (a), double (2D) (b), and triple (3D) layer fabrics (c).
Fig. 2. The contact force–time curves for the plain weave (1D) (a), double (2D) (b), and triple (3D) layer fabrics (c).
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Aktas et al. [3,4] investigated temperature effect on impact behavior and CAI strength of glass/epoxy composite plates subjected to various impact energies at room and high temperatures (40 °C, 60 °C, 80 °C, and 100 °C). Two stacking sequences as [0/90/0/90]s and [0/90/45/-45]s were tested to investigate the laminate orientation effects on the CAI strength and CAI damage mechanism. The results showed that the impact test temperature had significant effect on the CAI strength of the laminates. The maximum reduction in the CAI strength was obtained at 100 °C with the increasing impact energy while the minimum reduction in it was at 20 °C. Aktas et al. [12] studied impact response of unidirectional glass/epoxy laminates by considering the energy profile diagrams and associated load–deflection curves. They used two different stacking sequences for comparison. The main damage mode was found to be fiber fracture for the higher impact energies; whereas, it was delamination and matrix cracks for the smaller impact energies. Karakuzu et al. [13] investigated effect of impact energy, impactor mass and impact velocity on maximum contact force, maximum deflection, contact time, absorbed energy, and overall damage area of glass/epoxy laminated composites. They selected four different impact energies (10 J, 20 J, 30 J, and 40 J) and four impactor masses (5 kg, 10 kg, 15 kg, and 20 kg). The numerical analyses were done by using 3DIMPACT finite element code. The results showed that the high-mass impact caused initiation of the damage earlier and higher contact forces, more delaminations and contact time than the low-mass impact of the equal impact energy. Karakuzu et al. [14] studied impact behavior of glass/epoxy laminated composite plates with [0/±h/90]s of equal energy, equal velocity and equal impactor mass. They used five different ±h fiber directions as 15°, 30°, 45°, 60°, and 75° in order to examine the stacking sequence effect. Three different plate thicknesses of
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2.9 mm, 5.8 mm, and 8.7 mm were also selected to examine the thickness effect. The results showed that the lower impactor mass with higher impact velocity caused the greater contact forces. However, the lower impact energy with lower impact velocity and lower impact energy with lower impactor mass caused lower contact forces. Yu et al. [15] studied ballistic impact behavior of woven composites made of Kevlar/Vinylester and E-glass/Vinylester. The experimental study showed that the ballistic performance of the Kevlar/Vinylester was better than that of the E-glass/Vinylester composites. In the numerical simulation, the orthogonal isotropic constitutive equation with damage tensor and Hashin failure criterion was adopted. The simulation of the penetration process was presented and the residual velocity was calculated by fitting the experimental values. The numerical result showed that the compression/shear damage area existed in the vicinity of the impact side and a tensile damage area in the vicinity of the back side. Although there are considerable investigations about impact behavior of woven composite plates, almost no work has been done on impact and post-impact behavior of layer fabric composites. The present aims to point out that the impact and post impact behavior of plain weave (1D), double (2D), and triple (3D) layer fabrics based on E-glass/epoxy at room temperature. 2. Material production, preparation of impact and post impact samples One hundred and thirty tex glass yarn with a slight twisting was used to produce different layer fabrics. The glass fabrics were weaved with the Dornier weaving machine with working speed of 200 rpm, reed width of 150 cm, filling insertion system of rapier and shed formation of dobby (20 frame). Six frames were used for
Fig. 3. The contact force–deflection curves for the plain weave (1D) (a), double (2D) (b), and triple (3D) layer fabrics (c).
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the production of the layer fabrics. The connection between the layer fabrics was provided with extra warp yarns. Placement rate of between two and three-layer fabric warp yarns was 1top/1under/1extra (double layer fabric) or 1top/1middle/1under (triple layer fabric). 1D layer fabric has been weaved tighter with respect to 2D and 3D to reach nearly the same density. As a result of the weaving process, a plain weave (1D), double (2D), and triple (3D) layer fabrics having weight of approximately 509 g/m2 were manufactured. Schematic illustrations of the structures of the layer fabrics were shown in Fig. 1. The epoxy based on CY225 resin and HY225 hardener was used to manufacture the composite plate. The layered composite plate with eight plies was produced by hand lay-up technique at the Composite Manufacturing Laboratory of Usak University. A hot lamination press was used for fabrication of layered composite plates. For the curing process, the laminated plates were retained under 8 MPa constant pressure and at 110 °C for 100 min. Then, the composite plate was cooled to room temperature under the same pressure. The nominal thickness and fiber volume fraction of plain weave (1D), double (2D), and triple (3D) layer fabrics were approximately 3 mm and 55%, respectively. Although, the dimension of impact test samples were 100 100 mm2, the impact test specimens were cut from the composite plates as 100 150 mm2 using a diamond tip saw in order to investigate the post-impact (CAI) behavior of the layer fabrics.
(1D), double (2D), and triple (3D) layer fabric composites were impacted at room temperature under different energy levels. The impactor was manufactured from the stainless steel and has a hemispherical nose of 12.7 mm diameter. The impactor was connected to a force transducer with a maximum loading capacity of 22.4 kN. The total impact mass including impactor nose, force transducer and crosshead was 5.027 kg. The specimens of 100 150 mm2 were fixed by a pneumatic fixture with 76.2 mm hole diameter. Three impact tests were performed at each energy level and for the each layer fabrics. The Fractovis Plus impact test machine has software called VisualIMPACT which was given us the contact force between the impactor and the samples, impactor velocity and energy, and central deflection of the composite samples depend on time. The impact force value at each time step, F(t), were recorded by data acquisition system (DAS). The specimen deflection was calculated in main points. Deflection derives from a double integration of force curve as
di ¼
ZZ i
where di is deflection of the specimen up to point i, F(t) is force acquired by DAS, g is gravity acceleration and Mtotal is total impact mass. The velocity up to point i, derives from a single integration of force–time curve F(t) as
vi ¼
Z i
3. Experimental study
FðtÞ gM total 2 dt : Mtotal
FðtÞ gM total dt Mtotal
3.1. Impact tests
3.2. Post-impact (CAI) tests
The impact tests were performed with Fractovis Plus impact test machine in Composite Research Center at Department of Mechanical Engineering, Dokuz Eylül University. The plain weave
The post-impact (CAI) behavior of the impacted and non-impacted layer fabrics was determined at room temperature by using UMTS universal tensile machine with 50 kN load capacity at
Fig. 4. The energy-time curves for the plain weave (1D) (a), double (2D) (b), and triple (3D) layer fabrics (c).
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Department of Mechanical Engineering, Usak University. The postimpact tests were performed in accordance with the Boeing CAI test fixture (ASTM D 7137) for determination of CAI strengths of the layer fabric composites. The CAI test specimens were clamped at the top and bottom edges. To prevent buckling of the specimens under compressive load, a lateral support was provided. Compressive load was applied at a displacement rate of 1 mm/min. During the CAI tests, the force versus displacement history was recorded with a data acquisition system. The failure loads of the impacted and non-impacted layer fabric composite samples were obtained from the force–displacement curve. The first load which was reached to nonlinear part of the force–displacement curve was accepted as the critical CAI load [3–17]. Afterwards, the CAI strength of the specimens was calculated by dividing the crosssectional area of the samples.
4. Results and discussion 4.1. Impact and post impact behavior of layer fabrics The main objective of this study was to determine the perforation threshold of E-glass/epoxy composite having different layer fabrics. For this purpose, specimens with plain weave (1D), double (2D), and triple (3D) layer fabrics were impacted from 5 J to 60 J. However, for the sake of better understanding, a few certain energies were given in the contact force–time, contact force–deflection and energy-time curves (25, 35, 45, and 50 J for the 1D and 25, 35, 45, 50, 55, and 60 J for the 2D and 3D layer fabrics) (Figs. 2–4). The contact force–time curves for the layer fabrics were given in Fig. 2. It can be seen from Fig. 2, for all layer fabrics the contact time does not change significantly, while the contact force increases with the energy level. In addition, the contact force increases from 1D to 3D
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layer fabric. This result can be due to the higher strength of the triple layer fabric compared with the plain weave. The contact force–deflection curves of the structures were shown in Fig. 3. It can be clearly seen from the figure that permanent deflection of the composite plate increases by the increasing impact energy for all layer fabrics. The permanent deflection of 1D layer fabric is lower than that of the 2D and 3D layer fabrics up to the energy level of 45 J. However, beyond this energy level, it is higher than that of the 2D and 3D layer fabrics. The rebounding, penetration and perforation threshold of the impacted structures can be represented by the contact force–deflection curves. The penetration occurs at 45 J for the 1D layer fabrics; while at 55 J for the 2D and 3D layer fabrics. In addition, perforation occurs at 50 J for the 1D and at 60 J for the 2D and 3D layer fabrics. The perforation threshold of the 2D and 3D layer fabrics are nearly 20% higher than that of the 1D layer fabric. The energy-time curves for the layer fabrics were given in Fig. 4. It can be said from Fig. 4, the energy-time curve has generally three sub-curves; the first one is the linear part of the curves, which continues up to the maximum energy level. The second one starts at the maximum energy level and ends up at the constant energy level. The third one is the constant energy level. The difference between the maximum energy and constant energy levels gives the excessive energy. The excessive energy is retained in the impactor and used to rebound the impactor from specimen at the end of an impact event [12,16]. The constant energy level can be called absorbed energy of structures. When the constant energy level does not occur, it means that the composite is not perforated by the impactor. The excessive energy of the layer fabrics decreases by the increasing impact energy. This can be seen clearly by the energy profiling method, which will be discussed later. To investigate change in the maximum contact force, maximum contact time, maximum deflection and permanent deflection of
Fig. 5. The illustration of maximum contact force, maximum deflection, contact time, permanent deflection, impact energy and absorbed energy.
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Fig. 6. The maximum contact force (a), the maximum deflection (b), the contact time (c) and the permanent deflection (d) curves versus impact energy for the plain weave (1D), double (2D), and triple (3D) layer fabrics.
impacted layer fabrics, primarily, we must define these terms. For this purpose, Fig. 5 was given. It can be easily said that the maximum contact force is the highest value in the contact force–time curve. The maximum contact time is the value in contact force– time curve which meets with horizontal axis (Fig. 5a). The maximum deflection does not occur at the maximum contact force, it occurs at the nose of contact force–deflection curve. The permanent deflection is a value in the contact force–deflection curve where also meets with horizontal axis (Fig. 5b). The impact energy and absorbed energy were illustrated in Fig. 5c for the rebounding case. Impact energy is higher than the absorbed energy at the rebounding case. So, composite samples cannot absorb whole the impact energy that the impactor has. The maximum contact force, maximum deflection, contact time and permanent deflection curves versus impact energy for each layer fabrics were given in Fig. 6 for better understanding of the
impact behavior on the layer fabrics made of E-glass/epoxy composite materials. It can be seen from Fig. 6, the maximum contact force versus impact energy curves can be divided into three main regions. Since delamination and matrix cracks were occurred, the maximum contact force increases rapidly in the first region. It continues to increase gradually up to the perforation in the second region. In this region not only delamination and matrix cracks but also fiber cracks occur. In the last region, the composite specimen does not carry load due to catastrophic combine failure (Fig. 6a). The maximum deflection of the layer fabrics was increased linearly up to the perforation. After this energy level, it increases rapidly for the layer fabrics (Fig. 6b). The contact time was not changed remarkably up to the perforation of each layer fabrics (Fig. 6c). The trend of permanent deflection-impact energy curves for layer fabrics were nearly the same with the maximum deflection-impact energy curves (Fig. 6d).
Fig. 7. The energy profiling curves for the plain weave (1D), double (2D) and triple (3D) layer fabrics.
Fig. 8. The CAI strength-impact energy curves for the plain weave (1D), double (2D), and triple (3D) layer fabrics.
M. Aktasß et al. / Composite Structures 94 (2012) 2809–2818
Area under the contact force–deflection curve gives energy absorbed by the impacted specimen. The energy profiling diagram (Fig. 7) represents the relation between the impact energy and absorbed energy. In Fig. 7, the straight line from 0 J to 65 J is called equal energy line [1–2,4,12–14,16]. The gap between the curves
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for the layer fabrics and the equal energy line is called excessive energy. The maximum value of excessive energy was occurred at 22.5 J for the 1D (approx. 8.1 J) and at 45 J for 2D and 3D layer fabrics (approx. 7.6 J). This means, while the 1D layer fabrics absorbed 64% impact energy and has 36% excessive energy, the
Fig. 9. The impact damage of the plain weave (1D) layer fabric at 25 J (a), 45 J (b), and 50 J (c).
Fig. 10. The impact damage of the double (2D) layer fabric at 25 J (a), 55 J (b), and 60 J (c).
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2D and 3D layer fabrics absorbed approx. 83% impact energy and have 17% excessive energy. The CAI strength versus impact energy plots were shown in Fig. 8. It can be clearly seen from the figure that the CAI strength of each layer fabrics decreases by increasing impact energy. The CAI strengths of the 1D layer fabric were higher
than those of the 2D and 3D layer fabrics in the range of 5–22.5 J. However, in the range of 22.5–52.5 J, the CAI strengths were highest for 3D layer fabrics. The CAI strength was determined as 8.4 MPa, 4.7 MPa and 6.4 MPa for 1D, 2D, and 3D layer fabrics at 5 J impact energy levels, respectively. The CAI strength was
Fig. 11. The impact damage of the triple (3D) layer fabric at 25 J (a), 55 J (b), and 60 J (c).
Fig. 12. The impact and CAI damage of the plain weave (1D) layer fabric at 25 J (a), 45 J (b), and 50 J (c).
M. Aktasß et al. / Composite Structures 94 (2012) 2809–2818
deceived approx. 73.5% for 1D, 51.5% for 2D, and 52.1% for 3D layer fabrics at 50 J impact energy levels. It can be concluded from these results that the maximum reduction in CAI strength was obtained in 1D layer fabrics. However, the CAI reduction in 2D and 3D layer fabrics was nearly same.
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4.2. Damage mechanisms When a foreign object impacts on a composite laminate, several damage modes including delamination, edge delamination, fiber splitting, fiber cracking and matrix cracking can occur in the
Fig. 13. The impact and CAI damage of the double (2D) layer fabric at 25 J (a), 55 J (b), and 60 J (c).
Fig. 14. The impact and CAI damage of the triple (3D) layer fabric at 25 J (a), 55 J (b), and 60 J (c).
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composite laminate. These damage modes depend on the impact parameters such as the shape and mass of impactor, impact energy and dimension of composite laminate. The damage modes of layer fabrics were nearly same, but the energy level modes were different from each other. Three examples of the impacted specimens were given in Figs. 9–11 for the plain weave (1D), double (2D), and triple (3D) layer fabrics, respectively. The rebounding (Figs. 9a–11a), penetration (Figs. 9b–11b) and perforation (Figs. 9c–11c) level of the fabric composites were represented. The penetration and perforation occurred at 45 J and 50 J for the 1D layer fabrics, thus, the impact damage of the 1D layer fabrics at this situation was shown in Fig. 9b and c, respectively. It can be clearly seen from Figs. 9–11, the damage area increase by the increasing energy level. The main damage mode was observed as delamination and matrix cracking for 1D and only delamination for 2D and 3D layer fabrics under energy level of 25 J. It was observed as matrix cracking and fiber splitting for 1D (at 45 J) and only fiber splitting for 2D and 3D (at 55 J). Both matrix and fiber cracking were occurred in 1D at 50 J. Although the fiber cracking and edge delamination due to fiber cracking were occurred in 2D at 60 J. Only fiber cracking was observed in 3D layer fabrics at the same energy level. The impact and CAI damage of the layer fabrics were shown in Figs. 12–14. It can be seen from these figures that the CAI damage starts around the impact damage and progress up to edges of the specimens. The CAI damage of the 1D and 2D layer fabrics impacted at 25 J was not observed clearly. It can be said that the CAI damage of the impacted samples at perforated energy level progress nearly linear for all layer fabrics. The CAI damage for several impacted specimens start from edge of the specimen and continue up to the impact damage (Figs. 12b, 13b and 14b). 5. Conclusions This paper presents an experimental investigation on impact and post-impact (CAI) behavior of the plain weave (1D), double (2D), and triple (3D) layer fabric composite structures based on E-glass/epoxy. The concluding remarks can be summarized as follows: The minimum and maximum contact forces were observed from 1D and 3D layer fabrics, respectively. While the perforation threshold was observed at 50 J for the 1D, it occurred at 60 J for the 2D and 3D layer fabrics. Therefore, the perforation threshold of the 2D and 3D layer fabrics was nearly 20% higher than that of the 1D layer fabrics. The maximum deflection of layer fabrics increased linearly up to the perforation threshold and after this energy level; it increased rapidly for all layer fabrics. The excessive energy of layer fabrics decreased by the increasing impact energy. While the 1D layer fabric absorbed 64% impact energy and has 36% excessive energy, the 2D and 3D layer fabrics absorbed approx. 83% impact energy and have 17% excessive energy. The CAI strength decreased by the increasing impact energy for all layer fabrics. The CAI strengths of the 1D layer fabric were
higher than those of the 2D and 3D layer fabrics in the range of 5–22.5 J. However, in the range of 22.5–52.5 J, the CAI strengths were highest for the 3D layer fabric. The dominant damage mode observed was delamination and matrix cracking under the energy level of 25 J. It was observed as matrix cracking and fiber splitting at penetration energy level, and also observed as matrix cracking, fiber cracking and edge delamination at perforate energy level. The CAI damage generally started around the impact damage and it progressed up to edge of the specimens. However, it started from edge of the specimen up to the impact damage at the penetrated energy level for each layer fabrics.
Acknowledgements This study was sponsored by The Scientific and Technological Research Council of Turkey (TUBITAK), (Project No: 108M128). Partial financial support by Pul-tech FRP, in Usak-Turkey, was also gratefully acknowledged. References [1] Aktas M, Karakuzu R, Icten BM. Thermal impact behavior of glass–epoxy laminated composite plates. J Thermoplast Compos Mater 2011;24(4):535–53. [2] Icten BM, Atas C, Aktas M, Karakuzu R. Low temperature effect on impact response of quasi-isotropic glass/epoxy laminated plates. Compos Struct 2009;91:318–23. [3] Aktas M, Karakuzu R, Arman Y. Comparison after impact behavior of laminated composite plates subjected to low velocity impact in high temperature. Compos Struct 2009;89:77–82. [4] Aktas M, Karakuzu R, Icten BM. Impact behavior of glass/epoxy laminated composite plates at high temperatures. J Compos Mater 2010;4(19):2289–99. [5] Mathivanan NR, Jerald J. Experimental investigation of low-velocity impact characteristics of woven glass fiber epoxy matrix composite laminates of EP3 grade. Mater Des 2010;31:4553–60. [6] Baucom JN, Zikry MA, Rajendran AM. Low-velocity impact damage accumulation in woven S2-glass composite systems. Compos Sci Technol 2006;66:1229–38. [7] Shim VPW, Yang LM. Characterization of the residual mechanical properties of woven fabric reinforced composites after low-velocity impact. Int J Mech Sci 2005;47:647–65. [8] Hosur MV, Adbullah M, Jeelani S. Studies on the low-velocity impact response of woven hybrid composites. Compos Struct 2005;67:253–62. [9] Dehkordi MT, Nosraty H, Shokrieh MM, Minak G, Ghelli D. Low velocity impact properties of intra-ply hybrid composites based on basalt and nylon woven fabrics. Mater Des 2010;31:3835–44. [10] Sayer M, Bektas NB, Sayman O. An experimental investigation on the impact behavior of hybrid composite plates. Compos Struct 2010;92:256–1262. [11] Yin T, Rong MZ, Wu J, Chen H, Zhang MQ. Healing of impact damage in woven glass fabric reinforced epoxy composites. Compos: Part A 2008;39:12–1487. [12] Aktas M, Atas C, Icten BM, Karakuzu R. An experimental investigation of the impact response of composite laminates. Compos Struct 2009;87:307–13. [13] Karakuzu R, Erbil E, Aktas M. Impact characterization of glass/epoxy composite plates: an experimental and numerical study. Compos: Part B 2010;41: 388–95. [14] Karakuzu R, Erbil E, Aktas M. Damage prediction in glass/epoxy laminates subjected to impact loading. Indian J Eng 2010;17:186–98. [15] Yu YM, Wang XJ, Lim CW. Ballistic impact of 3D orthogonal woven composite by a spherical bullet: experimental study and numerical simulation. Int J Eng Appl Sci 2009;1:1–18. [16] Liu D. Characterization of impact properties and damage process of glass/ epoxy composite laminates. J Compos Mater 2004;38:1425–42. [17] Arman Y, Zor M, Aksoy S. Determination of critical delamination diameter of laminated composite plates under buckling loads. Compos Sci Technol 2006;66:2945–53.
Contents lists available at SciVerse ScienceDirect
Composite Structures journal homepage: www.elsevier.com/locate/compstruct
Impact and post impact behavior of layer fabric composites Mehmet Aktasß a,⇑, H. Ersen Balcıog˘lu a, Alaattin Aktasß b, Erkan Türker c, M. Emin Deniz d a
Usak University, Department of Mechanical Engineering, 64200 Usak, Turkey Istanbul University, Department of Mechanical Engineering, 34320 Istanbul, Turkey c Usak University, Department of Textile Engineering, 64200 Usak, Turkey d Harran University, Department of Mechanical Engineering, 63190 Sanliurfa, Turkey b
a r t i c l e
i n f o
Article history: Available online 23 April 2012 Keywords: Impact behavior Post-impact behavior Plain weave layer fabric Double layer fabric Triple layer fabric CAI strength
a b s t r a c t In this study, the effect of impact and post impact behavior of E-glass/epoxy composite plates having different layer fabrics were investigated by considering energy profile diagram and the related load– deflection curves. Different impact energies (5 J–60 J)were subjected to the plates consisting of eight layers of plain weave (1D), double (2D) and triple (3D) layer fabrics. The impact tests were continued until complete perforation of layer fabrics. The damage modes and damage processes of layer fabrics under varied impact energies were also discussed. At the end of the impact tests, the damaged samples were mounted into a compression apparatus to determine the Compression After Impact (CAI) strength of layer fabric samples. The results of these impact and post impact tests showed that contact force occurring between the impactor and the composite specimen increased and the CAI strength reduced by increasing the impact energy. The objective of this study was to determine the perforation threshold of E-glass/epoxy composite plates having different layer fabrics as plain weave (1D), double (2D), and triple (3D) layer fabrics. Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction Composite materials have excellent mechanical properties combined with low density. Therefore, composite materials have been used in a wide range of applications as aerospace, automotive, defense, and sport industries. In spite of having superior advantage, laminated composites are susceptible to damages under transverse impacts. Hence, the impact behavior of laminated composites has been an important research area for a long time [1–4]. Mathivanan and Jerald [5] have carried out an experimental investigation for concerning the low-velocity impact behavior of woven glass/epoxy composite laminates. The impact tests were conducted to characterize the type and extent of the damage observed in laminate of different thicknesses (2, 4, and 6 mm) subjected to different impact velocities. At the end of the tests, they found that the glass/epoxy composites have no sensitivity to the strain rate effect. Baucom et al. [6] have investigated damage accumulation in 2D and 3D woven glass/epoxy composite laminated plates under repeated impact loading. These plates contained different fabric architectures, fiber-volume fraction, and thickness. The woven composites were subjected to multiple impacts of 44 J at 4 m/s until perforation occurred. According to the test results, in 2D plates, the energy
⇑ Corresponding author. Tel.: +90 276 2212136/2727; fax: +90 276 2212137. E-mail address: [email protected] (M. Aktasß). 0263-8223/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.compstruct.2012.04.008
dissipated on the first strike ranged from about 21 J to 24 J. For the 3D plates, however, the initial energy dissipation was 25 J. Shim and Yang [7] examined the residual mechanical properties of crowfoot-weave carbon/epoxy laminates subjected to lowvelocity impact loading. It was found that the residual strength and stiffness of the impacted laminates decreased with increasing impact damage area. Hosur et al. [8] determined the impact response of four different combinations of hybrid laminates which have twill weave carbon fabric and plain weave S2-glass fabric using VARTM process with SC-15 epoxy resin system. The hybrid laminates were subjected to low-velocity impact loading at four energy levels of 10, 20, 30, and 40 J. Dehkordi et al. [9] investigated low-velocity impact behavior of homogenous and hybrid composite laminates reinforced by basalt–nylon intra-ply fabrics. They selected five different types of woven fabrics and five different volume fractions of nylon (0%, 25%, 33.3%, 50% and 100%). The effect of nylon/basalt fiber content on the maximum force, maximum deflection, residual deflection, total absorbed energy, elastic energy, size and type of damage were studied at several impact energies (16, 30 and 40 J). The results showed that the impact performance of these composites was significantly affected by the nylon/basalt fiber content. As a result, the elastic and total absorbed energy increased with the nylon/basalt fiber contents by increasing the impact energy. Sayer et al. [10] studied the impact behavior of hybrid composite plates. Impact tests were performed on two types of hybrid composite plates
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(glass–carbon/epoxy) until complete perforation of the specimens. The failure mechanisms of damaged specimens for different impact energies were evaluated by comparing the load–deflection curves and images of the damaged samples taken from impacted sides and non-impacted sides. The test results revealed that the perforation threshold of the hybrid composite with carbon facesheet was found approximately 30% higher than the hybrid composite with glass facesheet. Yin et al. [11] performed an experimental study for healing of impact damage in woven glass/epoxy composites with crack by pre-dispersing a novel repair system in the matrix. CAI tests were also conducted to evaluate mechanical performance of the lami-
nates before and after the crack healing. The experimental results indicated that the healing agent worked in repairing the matrix cracks generated by impact. Icten et al. [2] investigated impact behavior of laminated glass/epoxy composites under different impact energies ranging from 5 J to 70 J at low temperatures of 20oC, 20oC and 60oC. In this study, the maximum contact force, maximum deflection, maximum contact time and absorbed energy versus impact energy were determined. In order to determine the energy absorbing capability, the energy profiling method was utilized. The results showed that the ambient temperature highly affected the impact behavior of the composite materials and the damage area increased with the increasing impact energy.
Fig. 1. The schematic illustration of the plain weave (1D) (a), double (2D) (b), and triple (3D) layer fabrics (c).
Fig. 2. The contact force–time curves for the plain weave (1D) (a), double (2D) (b), and triple (3D) layer fabrics (c).
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Aktas et al. [3,4] investigated temperature effect on impact behavior and CAI strength of glass/epoxy composite plates subjected to various impact energies at room and high temperatures (40 °C, 60 °C, 80 °C, and 100 °C). Two stacking sequences as [0/90/0/90]s and [0/90/45/-45]s were tested to investigate the laminate orientation effects on the CAI strength and CAI damage mechanism. The results showed that the impact test temperature had significant effect on the CAI strength of the laminates. The maximum reduction in the CAI strength was obtained at 100 °C with the increasing impact energy while the minimum reduction in it was at 20 °C. Aktas et al. [12] studied impact response of unidirectional glass/epoxy laminates by considering the energy profile diagrams and associated load–deflection curves. They used two different stacking sequences for comparison. The main damage mode was found to be fiber fracture for the higher impact energies; whereas, it was delamination and matrix cracks for the smaller impact energies. Karakuzu et al. [13] investigated effect of impact energy, impactor mass and impact velocity on maximum contact force, maximum deflection, contact time, absorbed energy, and overall damage area of glass/epoxy laminated composites. They selected four different impact energies (10 J, 20 J, 30 J, and 40 J) and four impactor masses (5 kg, 10 kg, 15 kg, and 20 kg). The numerical analyses were done by using 3DIMPACT finite element code. The results showed that the high-mass impact caused initiation of the damage earlier and higher contact forces, more delaminations and contact time than the low-mass impact of the equal impact energy. Karakuzu et al. [14] studied impact behavior of glass/epoxy laminated composite plates with [0/±h/90]s of equal energy, equal velocity and equal impactor mass. They used five different ±h fiber directions as 15°, 30°, 45°, 60°, and 75° in order to examine the stacking sequence effect. Three different plate thicknesses of
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2.9 mm, 5.8 mm, and 8.7 mm were also selected to examine the thickness effect. The results showed that the lower impactor mass with higher impact velocity caused the greater contact forces. However, the lower impact energy with lower impact velocity and lower impact energy with lower impactor mass caused lower contact forces. Yu et al. [15] studied ballistic impact behavior of woven composites made of Kevlar/Vinylester and E-glass/Vinylester. The experimental study showed that the ballistic performance of the Kevlar/Vinylester was better than that of the E-glass/Vinylester composites. In the numerical simulation, the orthogonal isotropic constitutive equation with damage tensor and Hashin failure criterion was adopted. The simulation of the penetration process was presented and the residual velocity was calculated by fitting the experimental values. The numerical result showed that the compression/shear damage area existed in the vicinity of the impact side and a tensile damage area in the vicinity of the back side. Although there are considerable investigations about impact behavior of woven composite plates, almost no work has been done on impact and post-impact behavior of layer fabric composites. The present aims to point out that the impact and post impact behavior of plain weave (1D), double (2D), and triple (3D) layer fabrics based on E-glass/epoxy at room temperature. 2. Material production, preparation of impact and post impact samples One hundred and thirty tex glass yarn with a slight twisting was used to produce different layer fabrics. The glass fabrics were weaved with the Dornier weaving machine with working speed of 200 rpm, reed width of 150 cm, filling insertion system of rapier and shed formation of dobby (20 frame). Six frames were used for
Fig. 3. The contact force–deflection curves for the plain weave (1D) (a), double (2D) (b), and triple (3D) layer fabrics (c).
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the production of the layer fabrics. The connection between the layer fabrics was provided with extra warp yarns. Placement rate of between two and three-layer fabric warp yarns was 1top/1under/1extra (double layer fabric) or 1top/1middle/1under (triple layer fabric). 1D layer fabric has been weaved tighter with respect to 2D and 3D to reach nearly the same density. As a result of the weaving process, a plain weave (1D), double (2D), and triple (3D) layer fabrics having weight of approximately 509 g/m2 were manufactured. Schematic illustrations of the structures of the layer fabrics were shown in Fig. 1. The epoxy based on CY225 resin and HY225 hardener was used to manufacture the composite plate. The layered composite plate with eight plies was produced by hand lay-up technique at the Composite Manufacturing Laboratory of Usak University. A hot lamination press was used for fabrication of layered composite plates. For the curing process, the laminated plates were retained under 8 MPa constant pressure and at 110 °C for 100 min. Then, the composite plate was cooled to room temperature under the same pressure. The nominal thickness and fiber volume fraction of plain weave (1D), double (2D), and triple (3D) layer fabrics were approximately 3 mm and 55%, respectively. Although, the dimension of impact test samples were 100 100 mm2, the impact test specimens were cut from the composite plates as 100 150 mm2 using a diamond tip saw in order to investigate the post-impact (CAI) behavior of the layer fabrics.
(1D), double (2D), and triple (3D) layer fabric composites were impacted at room temperature under different energy levels. The impactor was manufactured from the stainless steel and has a hemispherical nose of 12.7 mm diameter. The impactor was connected to a force transducer with a maximum loading capacity of 22.4 kN. The total impact mass including impactor nose, force transducer and crosshead was 5.027 kg. The specimens of 100 150 mm2 were fixed by a pneumatic fixture with 76.2 mm hole diameter. Three impact tests were performed at each energy level and for the each layer fabrics. The Fractovis Plus impact test machine has software called VisualIMPACT which was given us the contact force between the impactor and the samples, impactor velocity and energy, and central deflection of the composite samples depend on time. The impact force value at each time step, F(t), were recorded by data acquisition system (DAS). The specimen deflection was calculated in main points. Deflection derives from a double integration of force curve as
di ¼
ZZ i
where di is deflection of the specimen up to point i, F(t) is force acquired by DAS, g is gravity acceleration and Mtotal is total impact mass. The velocity up to point i, derives from a single integration of force–time curve F(t) as
vi ¼
Z i
3. Experimental study
FðtÞ gM total 2 dt : Mtotal
FðtÞ gM total dt Mtotal
3.1. Impact tests
3.2. Post-impact (CAI) tests
The impact tests were performed with Fractovis Plus impact test machine in Composite Research Center at Department of Mechanical Engineering, Dokuz Eylül University. The plain weave
The post-impact (CAI) behavior of the impacted and non-impacted layer fabrics was determined at room temperature by using UMTS universal tensile machine with 50 kN load capacity at
Fig. 4. The energy-time curves for the plain weave (1D) (a), double (2D) (b), and triple (3D) layer fabrics (c).
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Department of Mechanical Engineering, Usak University. The postimpact tests were performed in accordance with the Boeing CAI test fixture (ASTM D 7137) for determination of CAI strengths of the layer fabric composites. The CAI test specimens were clamped at the top and bottom edges. To prevent buckling of the specimens under compressive load, a lateral support was provided. Compressive load was applied at a displacement rate of 1 mm/min. During the CAI tests, the force versus displacement history was recorded with a data acquisition system. The failure loads of the impacted and non-impacted layer fabric composite samples were obtained from the force–displacement curve. The first load which was reached to nonlinear part of the force–displacement curve was accepted as the critical CAI load [3–17]. Afterwards, the CAI strength of the specimens was calculated by dividing the crosssectional area of the samples.
4. Results and discussion 4.1. Impact and post impact behavior of layer fabrics The main objective of this study was to determine the perforation threshold of E-glass/epoxy composite having different layer fabrics. For this purpose, specimens with plain weave (1D), double (2D), and triple (3D) layer fabrics were impacted from 5 J to 60 J. However, for the sake of better understanding, a few certain energies were given in the contact force–time, contact force–deflection and energy-time curves (25, 35, 45, and 50 J for the 1D and 25, 35, 45, 50, 55, and 60 J for the 2D and 3D layer fabrics) (Figs. 2–4). The contact force–time curves for the layer fabrics were given in Fig. 2. It can be seen from Fig. 2, for all layer fabrics the contact time does not change significantly, while the contact force increases with the energy level. In addition, the contact force increases from 1D to 3D
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layer fabric. This result can be due to the higher strength of the triple layer fabric compared with the plain weave. The contact force–deflection curves of the structures were shown in Fig. 3. It can be clearly seen from the figure that permanent deflection of the composite plate increases by the increasing impact energy for all layer fabrics. The permanent deflection of 1D layer fabric is lower than that of the 2D and 3D layer fabrics up to the energy level of 45 J. However, beyond this energy level, it is higher than that of the 2D and 3D layer fabrics. The rebounding, penetration and perforation threshold of the impacted structures can be represented by the contact force–deflection curves. The penetration occurs at 45 J for the 1D layer fabrics; while at 55 J for the 2D and 3D layer fabrics. In addition, perforation occurs at 50 J for the 1D and at 60 J for the 2D and 3D layer fabrics. The perforation threshold of the 2D and 3D layer fabrics are nearly 20% higher than that of the 1D layer fabric. The energy-time curves for the layer fabrics were given in Fig. 4. It can be said from Fig. 4, the energy-time curve has generally three sub-curves; the first one is the linear part of the curves, which continues up to the maximum energy level. The second one starts at the maximum energy level and ends up at the constant energy level. The third one is the constant energy level. The difference between the maximum energy and constant energy levels gives the excessive energy. The excessive energy is retained in the impactor and used to rebound the impactor from specimen at the end of an impact event [12,16]. The constant energy level can be called absorbed energy of structures. When the constant energy level does not occur, it means that the composite is not perforated by the impactor. The excessive energy of the layer fabrics decreases by the increasing impact energy. This can be seen clearly by the energy profiling method, which will be discussed later. To investigate change in the maximum contact force, maximum contact time, maximum deflection and permanent deflection of
Fig. 5. The illustration of maximum contact force, maximum deflection, contact time, permanent deflection, impact energy and absorbed energy.
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Fig. 6. The maximum contact force (a), the maximum deflection (b), the contact time (c) and the permanent deflection (d) curves versus impact energy for the plain weave (1D), double (2D), and triple (3D) layer fabrics.
impacted layer fabrics, primarily, we must define these terms. For this purpose, Fig. 5 was given. It can be easily said that the maximum contact force is the highest value in the contact force–time curve. The maximum contact time is the value in contact force– time curve which meets with horizontal axis (Fig. 5a). The maximum deflection does not occur at the maximum contact force, it occurs at the nose of contact force–deflection curve. The permanent deflection is a value in the contact force–deflection curve where also meets with horizontal axis (Fig. 5b). The impact energy and absorbed energy were illustrated in Fig. 5c for the rebounding case. Impact energy is higher than the absorbed energy at the rebounding case. So, composite samples cannot absorb whole the impact energy that the impactor has. The maximum contact force, maximum deflection, contact time and permanent deflection curves versus impact energy for each layer fabrics were given in Fig. 6 for better understanding of the
impact behavior on the layer fabrics made of E-glass/epoxy composite materials. It can be seen from Fig. 6, the maximum contact force versus impact energy curves can be divided into three main regions. Since delamination and matrix cracks were occurred, the maximum contact force increases rapidly in the first region. It continues to increase gradually up to the perforation in the second region. In this region not only delamination and matrix cracks but also fiber cracks occur. In the last region, the composite specimen does not carry load due to catastrophic combine failure (Fig. 6a). The maximum deflection of the layer fabrics was increased linearly up to the perforation. After this energy level, it increases rapidly for the layer fabrics (Fig. 6b). The contact time was not changed remarkably up to the perforation of each layer fabrics (Fig. 6c). The trend of permanent deflection-impact energy curves for layer fabrics were nearly the same with the maximum deflection-impact energy curves (Fig. 6d).
Fig. 7. The energy profiling curves for the plain weave (1D), double (2D) and triple (3D) layer fabrics.
Fig. 8. The CAI strength-impact energy curves for the plain weave (1D), double (2D), and triple (3D) layer fabrics.
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Area under the contact force–deflection curve gives energy absorbed by the impacted specimen. The energy profiling diagram (Fig. 7) represents the relation between the impact energy and absorbed energy. In Fig. 7, the straight line from 0 J to 65 J is called equal energy line [1–2,4,12–14,16]. The gap between the curves
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for the layer fabrics and the equal energy line is called excessive energy. The maximum value of excessive energy was occurred at 22.5 J for the 1D (approx. 8.1 J) and at 45 J for 2D and 3D layer fabrics (approx. 7.6 J). This means, while the 1D layer fabrics absorbed 64% impact energy and has 36% excessive energy, the
Fig. 9. The impact damage of the plain weave (1D) layer fabric at 25 J (a), 45 J (b), and 50 J (c).
Fig. 10. The impact damage of the double (2D) layer fabric at 25 J (a), 55 J (b), and 60 J (c).
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2D and 3D layer fabrics absorbed approx. 83% impact energy and have 17% excessive energy. The CAI strength versus impact energy plots were shown in Fig. 8. It can be clearly seen from the figure that the CAI strength of each layer fabrics decreases by increasing impact energy. The CAI strengths of the 1D layer fabric were higher
than those of the 2D and 3D layer fabrics in the range of 5–22.5 J. However, in the range of 22.5–52.5 J, the CAI strengths were highest for 3D layer fabrics. The CAI strength was determined as 8.4 MPa, 4.7 MPa and 6.4 MPa for 1D, 2D, and 3D layer fabrics at 5 J impact energy levels, respectively. The CAI strength was
Fig. 11. The impact damage of the triple (3D) layer fabric at 25 J (a), 55 J (b), and 60 J (c).
Fig. 12. The impact and CAI damage of the plain weave (1D) layer fabric at 25 J (a), 45 J (b), and 50 J (c).
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deceived approx. 73.5% for 1D, 51.5% for 2D, and 52.1% for 3D layer fabrics at 50 J impact energy levels. It can be concluded from these results that the maximum reduction in CAI strength was obtained in 1D layer fabrics. However, the CAI reduction in 2D and 3D layer fabrics was nearly same.
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4.2. Damage mechanisms When a foreign object impacts on a composite laminate, several damage modes including delamination, edge delamination, fiber splitting, fiber cracking and matrix cracking can occur in the
Fig. 13. The impact and CAI damage of the double (2D) layer fabric at 25 J (a), 55 J (b), and 60 J (c).
Fig. 14. The impact and CAI damage of the triple (3D) layer fabric at 25 J (a), 55 J (b), and 60 J (c).
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composite laminate. These damage modes depend on the impact parameters such as the shape and mass of impactor, impact energy and dimension of composite laminate. The damage modes of layer fabrics were nearly same, but the energy level modes were different from each other. Three examples of the impacted specimens were given in Figs. 9–11 for the plain weave (1D), double (2D), and triple (3D) layer fabrics, respectively. The rebounding (Figs. 9a–11a), penetration (Figs. 9b–11b) and perforation (Figs. 9c–11c) level of the fabric composites were represented. The penetration and perforation occurred at 45 J and 50 J for the 1D layer fabrics, thus, the impact damage of the 1D layer fabrics at this situation was shown in Fig. 9b and c, respectively. It can be clearly seen from Figs. 9–11, the damage area increase by the increasing energy level. The main damage mode was observed as delamination and matrix cracking for 1D and only delamination for 2D and 3D layer fabrics under energy level of 25 J. It was observed as matrix cracking and fiber splitting for 1D (at 45 J) and only fiber splitting for 2D and 3D (at 55 J). Both matrix and fiber cracking were occurred in 1D at 50 J. Although the fiber cracking and edge delamination due to fiber cracking were occurred in 2D at 60 J. Only fiber cracking was observed in 3D layer fabrics at the same energy level. The impact and CAI damage of the layer fabrics were shown in Figs. 12–14. It can be seen from these figures that the CAI damage starts around the impact damage and progress up to edges of the specimens. The CAI damage of the 1D and 2D layer fabrics impacted at 25 J was not observed clearly. It can be said that the CAI damage of the impacted samples at perforated energy level progress nearly linear for all layer fabrics. The CAI damage for several impacted specimens start from edge of the specimen and continue up to the impact damage (Figs. 12b, 13b and 14b). 5. Conclusions This paper presents an experimental investigation on impact and post-impact (CAI) behavior of the plain weave (1D), double (2D), and triple (3D) layer fabric composite structures based on E-glass/epoxy. The concluding remarks can be summarized as follows: The minimum and maximum contact forces were observed from 1D and 3D layer fabrics, respectively. While the perforation threshold was observed at 50 J for the 1D, it occurred at 60 J for the 2D and 3D layer fabrics. Therefore, the perforation threshold of the 2D and 3D layer fabrics was nearly 20% higher than that of the 1D layer fabrics. The maximum deflection of layer fabrics increased linearly up to the perforation threshold and after this energy level; it increased rapidly for all layer fabrics. The excessive energy of layer fabrics decreased by the increasing impact energy. While the 1D layer fabric absorbed 64% impact energy and has 36% excessive energy, the 2D and 3D layer fabrics absorbed approx. 83% impact energy and have 17% excessive energy. The CAI strength decreased by the increasing impact energy for all layer fabrics. The CAI strengths of the 1D layer fabric were
higher than those of the 2D and 3D layer fabrics in the range of 5–22.5 J. However, in the range of 22.5–52.5 J, the CAI strengths were highest for the 3D layer fabric. The dominant damage mode observed was delamination and matrix cracking under the energy level of 25 J. It was observed as matrix cracking and fiber splitting at penetration energy level, and also observed as matrix cracking, fiber cracking and edge delamination at perforate energy level. The CAI damage generally started around the impact damage and it progressed up to edge of the specimens. However, it started from edge of the specimen up to the impact damage at the penetrated energy level for each layer fabrics.
Acknowledgements This study was sponsored by The Scientific and Technological Research Council of Turkey (TUBITAK), (Project No: 108M128). Partial financial support by Pul-tech FRP, in Usak-Turkey, was also gratefully acknowledged. References [1] Aktas M, Karakuzu R, Icten BM. Thermal impact behavior of glass–epoxy laminated composite plates. J Thermoplast Compos Mater 2011;24(4):535–53. [2] Icten BM, Atas C, Aktas M, Karakuzu R. Low temperature effect on impact response of quasi-isotropic glass/epoxy laminated plates. Compos Struct 2009;91:318–23. [3] Aktas M, Karakuzu R, Arman Y. Comparison after impact behavior of laminated composite plates subjected to low velocity impact in high temperature. Compos Struct 2009;89:77–82. [4] Aktas M, Karakuzu R, Icten BM. Impact behavior of glass/epoxy laminated composite plates at high temperatures. J Compos Mater 2010;4(19):2289–99. [5] Mathivanan NR, Jerald J. Experimental investigation of low-velocity impact characteristics of woven glass fiber epoxy matrix composite laminates of EP3 grade. Mater Des 2010;31:4553–60. [6] Baucom JN, Zikry MA, Rajendran AM. Low-velocity impact damage accumulation in woven S2-glass composite systems. Compos Sci Technol 2006;66:1229–38. [7] Shim VPW, Yang LM. Characterization of the residual mechanical properties of woven fabric reinforced composites after low-velocity impact. Int J Mech Sci 2005;47:647–65. [8] Hosur MV, Adbullah M, Jeelani S. Studies on the low-velocity impact response of woven hybrid composites. Compos Struct 2005;67:253–62. [9] Dehkordi MT, Nosraty H, Shokrieh MM, Minak G, Ghelli D. Low velocity impact properties of intra-ply hybrid composites based on basalt and nylon woven fabrics. Mater Des 2010;31:3835–44. [10] Sayer M, Bektas NB, Sayman O. An experimental investigation on the impact behavior of hybrid composite plates. Compos Struct 2010;92:256–1262. [11] Yin T, Rong MZ, Wu J, Chen H, Zhang MQ. Healing of impact damage in woven glass fabric reinforced epoxy composites. Compos: Part A 2008;39:12–1487. [12] Aktas M, Atas C, Icten BM, Karakuzu R. An experimental investigation of the impact response of composite laminates. Compos Struct 2009;87:307–13. [13] Karakuzu R, Erbil E, Aktas M. Impact characterization of glass/epoxy composite plates: an experimental and numerical study. Compos: Part B 2010;41: 388–95. [14] Karakuzu R, Erbil E, Aktas M. Damage prediction in glass/epoxy laminates subjected to impact loading. Indian J Eng 2010;17:186–98. [15] Yu YM, Wang XJ, Lim CW. Ballistic impact of 3D orthogonal woven composite by a spherical bullet: experimental study and numerical simulation. Int J Eng Appl Sci 2009;1:1–18. [16] Liu D. Characterization of impact properties and damage process of glass/ epoxy composite laminates. J Compos Mater 2004;38:1425–42. [17] Arman Y, Zor M, Aksoy S. Determination of critical delamination diameter of laminated composite plates under buckling loads. Compos Sci Technol 2006;66:2945–53.