The Influence of impact on Composite Armour System Kevlar-29/polyester-Al 2 O 3. IOP Conference Series: Materials Science and Engineering

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1 IOP Conference Series: Materials Science and Engineering The Influence of impact on Composite Armour System Kevlar-29/polyester-Al 2 O 3 To cite this article: A A Ramadhan et al 20 IOP Conf. Ser.: Mater. Sci. Eng View the article online for updates and enhancements. Related content - The effect of interlaminar graphene nanosheets reinforced e-glass fiber/ epoxy on low velocity impact response of a composite plate A Y Al-Maharma and P Sendur - A numerical study on dynamic failure of nanomaterial enhanced laminated glass under impact C D Wu, X Q Yan and L M Shen - Mechanical behavior of glass/epoxy composite laminate with varying amount of MWCNTs under different loadings K K Singh and Prashant Rawat Recent citations - Study on Ballistic Energy Absorption Capability of Glass-Epoxy and Jute-Epoxy- Rubber Sandwich Composites Sangamesh Rajole et al This content was downloaded from IP address on 09/03/2019 at :1

2 The Influence of impact on Composite Armour System Kevlar-29/polyester-Al 2 O 3 A A Ramadhan, A R Abu Talib 1, A S Mohd Rafie and R Zahari Department of Aerospace Engineering, Universiti Putra Malaysia, 300 Selangor, Malaysia 1 : abrahim@eng.upm.edu.my Abstract..An experimental investigation of high velocity impact responses of composite laminated plates using a helium gas gun has been presented in this paper. The aim of this study was to develop the novel composite structure that meets the specific requirements of ballistic resistance which used for body protections, vehicles and other applications. Thus the high velocity impact tests were performed on composite Kevlar-29 fiber/polyester resin with alumina powder (Al 2 O 3 ). The impact test was conducted by using a cylindrical steel projectile of 7.62mm diameter at a velocity range of m/s. The results (shown in this work) are in terms of varying plate thickness and the amount of energy absorbed by the laminated plates meanwhile we obtained that the mm thickness of composite plate suitable for impact loading up to 200m/s impact velocity. Therefore this composite structure (it is used to reduce the amount of Kevlar) considered most economical armoure products. We used the ANSYS AUTODYN 3D- v. software for our simulations. The results have been obtained a.1% maximum errors with experimental work of energy absorption. NOMENCLATURE E 1 E 2 V f V i V r E Abs m p V b Density (g/cm3) Poisson s ratio Longitudinal Young s Modulus (GN/m2) Transverse Young s Modulus (GN/m2) Volume fraction of fiber (N/m) Initial velocity (m/s) Residual velocity (m/s) Energy Absorption by the specimen (J) Mass of bullet (Kg) Ballistic limit velocity (m/s) 1. Introduction Human s protection has been an important issue since the beginning of creation. Throughout the recorded history, there have been various types of material that are utilized as protection garments from injury, such as in battles and other dangerous situations.[1]. The study of energy absorption behavior of metallic plates subjected to projectile impact requires attention due to the wide range of applications and complex nature of the problem. Extensive research Published under licence by IOP Publishing Ltd 1

3 has been carried out in the past [2, 3] to understand various features of this complex phenomenon both from the point of view of the projectile as well as the target plate by using deferent impact conditions and varying target configuration. R. Barauskas and A. Abraitiene et al []. used finite element model of the ballistic test against the multi-layer textiles package structure and they developed in LS-DYNA. The bullet has been considered as a deformable body in contact with the fabric package represented by an interwoven yarn structure. The energy absorption characteristics of thin single as well as layered in-contact aluminum target plates of different thicknesses impacted by blunt, ogive and hemispherical nosed steel projectiles. Influence of various parameters affecting the energy absorption capacity of the target, such as kinetic energy of the impact- ing projectile and its nose shape, configuration of the target plate, its mode of failure as well as thickness of the target plate was studied. The experimental findings were also verified with the numerical sim- ulations carried out using finite element code ABAQUS. Energy absorption capacity of the target plates obtained from the numerical analysis was found in good agreement with the experimental observations.[5]. Furthermore, the impact response of a non-woven symmetrical CFRP laminate has been compared to that of a woven laminate over an impact-energy regime of 92 J to 59 J. At lower impact- energies there were strong indications that the non-woven laminate out-performed the woven laminate whereas at the higher impact-energies the ballistic performance was seen to be approximately the same.[6], while the compression strengths of the polyester resins were found by M. Piggott and B. Harris [7]. Designing ballistic barriers of Kevlar 29 plates, based solely on physical models, would require a large number of experimental data, which are time consuming and costly to generate. Recent advances towards understanding damage mechanisms of laminated composites, (e.g. [ 10]) offer the possibility of avoiding many of the experimental tests by using computational simulation, bearing in mind that the numerical results should be used with precaution and be always certified by experimental tests. The novel sandwich plate (Kevlar29/epoxy-Al 2 O 3 ) laminated plate fabricated in this research can be contributed in many applications like Vehicle, body Armour, aerospace and military applications. The high velocity impact response of fiber (mm, mm and mm) thicknesses of this composite material presented in this work by using cylindrical bullets type 30 steel projectiles. Effects of projectile velocity, thickness of plates on the ballistic impact and energy absorption behavior of the targets are investigated experimentally and numerically simulation. The simulations are carried out using ANSYS AUTODYN 3D- v. software. 2. Experimental methodology 2.1. Materials used, properties and fabricating the specimens The materials used in this work as follow as Woven fiber Kevlar-29 Polyester. Alumina (Al 2 O 3 ) powder. The mechanical properties of these materials have been specified in table 1 as bellow The volume fraction of fiber V f (fiber volume/total volume) in composites is very often significantly less than 100%, and it was tested by Amotz and Schwartz [11] as shown in table 2, so the volume fraction was selected 55% in this work, it was a optimum value compared with others volume fraction for fabricating the specimens. 2

4 Table 1 The mechanical properties of fiber Kevlar-29 as shown in table 1 bellow Properties Material Kevlar-29 Polyester Alumina a fiber (6061-T6) resin a Density (g/cm3) Ultimate Tensile strength(mpa) Tensile Yield Strength (MPa) Modulus of Elasticity (GPa) Poisson s Ratio Fatigue Strength (MPa) 96.5 Shear Strength (MPa) 207 The advancement in designing a new composite constructor is embodied in the composite compounds arrangement and the tactical ways that are depended on the assembled layers. Meanwhile, the target geometry is a sensitive point in this investigation, and the adjacent panels have the responsibility to increase energy absorption by the targets. The target preparation processes include composite preparation and geometry of the target. Hence, the composite was constructed from the Kevlar29 and polyester resin mixed with alumina powder, since the target area was cm, as illustrated in Figure.1 Figure 1. Kevlar29/polyester-Al 2 O 3 laminated plate Three thicknesses (, and mm) of specimens were fabricated by using Hand lay-up method of all the specimens. Woven roving Kevlar-29 fibre is wound manually in the open mold of glass, which was coated with wax to easily remove the specimen later, and polyester resin mixed with alumina powder by mixer until homogenous occurred the ratio of polyester to alumina powder is 2:1, then brushed over and into the woven roving Kevlar-29 fibre, The time of solidification is about 72 hours to provide optimum blend. The tensile test as shown in figure 2, compression test also achieved in this work to obtain the basic mechanical properties to obtain the result of stress strain curve as shown in figure 3 of tensile and compression test for this laminated plate which it used later in simulation work, but the main objective in this work was fabricated novel sandwich structure and tested it under high impact loading. 3

5 Figure 2.Specimens under tensile test Stress (Mpa) Strain (10^-3) Tensile test Compression test Figure 3. Stress-strain curve for tensile and compression test loading of Kevlar29/polyester with Al 2 O 3 laminated plate. The volume fraction used in all specimens fabricated is 55% and the total specimens were tested in this work 27 laminated plates; for compression and tensile test 6 and for high velocity impact test 21 specimens were subjected to cylindrical bullet with different initial velocity impact as shown in table 1. Table 1. The volume fraction and number of specimens used in experimental work. Thickness (mm) No. of Kevlar- 29 layers Volume fraction (V f ) Initial Velocity impact m/s No. of specimens % 55% 55% 160, 200,20,20,320,360,00 160, 200,20,20,320,360,00 160, 200,20,20,320,360,

6 2.2. Gas Gun and Bullet selection The instrumented impact test equipment used in this study was a gas gun impact tester M. T. H. Sultan [] shown in Figure. The general features of the testing apparatus are shown in Figure 5 has been designed in order to launch the projectile. The main components of the gas gun are the 2200 Psi pressure tank, the purpose-built "ring section for compressed gas, the m long smooth barrel and (60, 60 and 0 cm) dimensions of box chamber to hold the specimen inside this box which it has (60 x 60 cm) framing window to observe the behavior of target and bullet by photography high speed camera (200,000 fps) for this work. Figure. Gas gun tunnel to test the specimens. Figure 5. Gas gun tunnel (instrument impact tester). 5

7 The specimen mounted by (25 x 25cm) two frames to prevent the movement during the impact test as shown in figure 6. Iron frame for mounting Specimen Figure 6.The target mounted with holding frame. The gas gun is capable of launching three (cylindrical, spherical and nose tip) but in this work used cylindrical shape of 7.62mm diameter steel projectile and 5g of 30 steel bullet (as shown in figure 7) package to a range of velocity of m/s when helium is used as a propellant gas. Cylindrical steel bullet Figure 7.Cylindrical steel 30 bullet Impact Testing The impact testing was Installed the composite of woven Kevlar-29/polyester with alumina (Al 2 O 3 ) laminated plates of square shape (100 x 100 mm) with different (, and mm) thicknesses dimensions inside the specimen holder and focused the high speed camera with suitable resolution (200,000 fps) and adjusted the lights to get optimum conditions before test. However, both the aligning of the system and the luminance during testing are crucial parameters in order to have good, reliable images. As indicated above, the high-speed camera system is used for measuring the velocity of projectiles. This is made possible by advanced image processing of the digital pictures which it s connected with P.C. to calculate the time of bullet before impact and after penetration if accrued of specimens as shown in figure an example of 20 m/s velocity impact. The most important feature is the possibility to obtain the initial and residual velocity by the following equations: v i = S 1 t 1 and (1) 6

8 V r = S 2 (2) t 2 Where V i and V r initial and residual velocity (m/s) respectively S 1 and S 2 displacement before and after penetration (m) respectively and t 1, t 2 time before and after penetration (s) respectively. Figure. Frames record history by high velocity impact during impact test of specimen The total energy absorption by the specimen according to the following equation : E Abs = 1 2 m p V i 2 V r 2 or E Abs = 1 2 m pv b 2 (3) V b = V i 2 V r 2 Where E Abs = Energy Absorption by the specimen (J), m p = mass of bullet (Kg) and V b = ballistic velocity (m/s). 3. Description of the numerical model 3.1 Material modeling The main properties of fiber Kevlar29/polyester -Alumina (Al 2 O 3 ) and Steel 30 were used in this simulation at room temperature condition shown in tables 2 and 3. Table 2. Kevlar29/polyester-Alumina(Al 2 O 3 ) (orthotropic) Shear Poisson's Poisson's Poisson's E 11 (Kpa) E 22 (Kpa) E 33 (Kpa Modulus Ratio XY Ratio YZ Ratio XZ XY Pa Shear Modulus YZ Pa Shear Modulus XZ Pa 1.15e e e e-00 1.e-00 1.e-00 The Johnson-Cook failure model has been used for projectile material, deformations were observed in the cylindrical steel 30 bullet as shown in table 3. 7

9 Initial Yield Stress Pa Density Kg/m 3 Table 3. Steel 30 impactor (Johnson Cook Strength) Bulk Thermal Strain Rate Modulus Softening Constant (Pa) Exponent Melting Temperature C Reference Strain Rate (/sec) 7.92e e e Finite element mesh and Autodyn simulation The finite element model by Lagrange model using ANSYS v.1, where a sandwich plate is idealized using the same conditions in experimental work like fixed ended of plate thickness of plates mechanical properties, initial velocity of bullet and the properties of bullet as shown in figures 9 and 10-a. Explicit mesh element of 1551 nodes and elements for mm, 1339 nodes and elements for mm, 703 nodes 5000 elements for 5mm target thickness, while for the bullet 3 nodes and 266 elements was used to simulate the target and the impactor by Academic Autodyn 3D version.1 as illustrated in figures 10,11 and that show also the damage view occurring during different time. Each layer of the plate was modeled using two solid elements through the thickness, and the minimal element size was 0.2 x 0.2 mm at the plate, which was the point of impact Figure 9. mm target of Kevlar29/polyester and Al 2 O 3 fixed ended subjected to cylindrical steel bullet at time 0 ms and cycle 0.

10 Figure 10. mm target of Kevlar29/polyester and Al 2 O 3 subjected to 200m/s cylindrical steel bullet a- explicit mesh and b-stress damage occurred at time 3. ms. Figure 11. Back view stress damage of mm target of Kevlar29/polyester and Al 2 O 3 subjected to 200m/s cylindrical steel bullet (a) at time 5.6ms and (b) at time.2ms. Figure. The damage of mm target of Kevlar29/polyester and Al 2 O 3 subjected to 00m/s cylindrical steel bullet (a) at time 109ms and (b) at time 159ms. 9

11 . Results and discussion The predicted damages by Autodyn-3D v.1 software of the composite Kevlar29/polyester-Al 2 O 3 laminated plates perforating listed in table with different (, and mm) thicknesses at range of ( m/s) strike velocities of steel 30 bullet, an example of (100 x 100 x mm) target under 20 m/s shown in figures 13 at different history cycles, this figure shows the stress and strain distribution which it results by the damage occurred in the specimen, hence the simulation was done as the same conditions in experimental work so as to obtain good comparison. To comparison the damage occurred during this simulation with experimental test Figure1 shows the specimen tested of mm thickness of laminated plate and, while figure 15 for impactor steel bullet. Figure 13. The stress and strain of (100 x 100 x mm) Kevlar29/polyester and Al2O3 subjected to 20 m/s Steel 30 at different times. Figure 1. Comparison of the perforated damage in the fabric target in the experimental and theoretical analyses: (a) simulated and (b) observed Figure 15. The damage occurred of Steel30 bullet at 00m/s velocity on mm thickness of target (a) simulated and (b) observed The initial velocity versus residual velocity of (, and mm) laminated plated thicknesses subjected to rang of impact velocity (10-00 m/s) steel bullet was presented in figure16 which it shows decreasing the residual velocities with increasing thickness of targets until no penetration occurred via mm thickness of laminated plate especially at initial velocity less than 200 m/s. 10

12 250 Residual Velocity (m/s) mm mm mm Initial Velocity (m/s) Figure 16. Simulation of time versus velocity of mm target (Front, Middle and back stacking sequence Al plate) plate subjected to 20 m/s steel bullet. Figures 17 and 1 presented the experimental and simulation results respectively of initial velocity versus energy absorption of (, and mm) thicknesses of kevlar29/polyester with alumina laminated plates. The numerical simulation by using Autodyn-3D v.1 obtained a good approximation to the experimental results Energy Absorption (J) Initial Velocity (m/s) E.Absorb.mm.thick.Expt. E.Absorb.mm.thick.Expt. E.Absorb.mm.thick.Expt. Figure 17. Experimental work of initial velocity versus energy absorption of mm, mm and mm targets laminated plate subjected to range ( m/s) steel bullet. 11

13 The velocity history during impact also dependent on the thickness of plate as shown in figure 19, that shows an example of 200m/s of initial velocity for different thickness of kevlar29/polyester with alumina laminated plates, the time of drop slop increase with the thickness of plate Energy Absrption (J) Initial Velocity (m/s) E.Absorb.mm.thick.Sim. E.Absorb.mm.thick.Sim. E.Absorb.mm.thick.Sim. Figure 1. Simulation of initial velocity versus energy absorption of mm, mm and mm targets laminated plate subjected to range ( m/s) steel bullet Velocity (m/s) Time(ms) mm thick. Sim mm thick. Sim mm thick. Sim Figure 19. Simulation of initial velocity versus energy absorption of mm, mm and mm targets laminated plate subjected to range ( m/s) steel bullet.

14 The energy absorption was studied in this work to obtain the optimum results value and it were found the maximum relative error of energy absorption between simulation and experimental values is.1% for overall results obtained with different thickness and initial velocity of composite laminated plates as shown in table. Table. Experimental and simulation results of residual velocity and energy absorption of, and mm thickness of Kevlar/polyester-Al 2 O 3 laminated plate at different initial velocity. Thick (mm) V i (m/s) V r (m/s) V r (m/s) Error E. Absorption E. Absorption. Error Simulation Experimental (%) Simulation (J) Experimental (J) (%) From above table it has seen clear affect the thickness of target plate on the behavior of residual velocity which it leads to affect on the energy absorption with different velocity. 5. Conclusions As a summary of this work, the following conclusions could be found: The energy absorption of the composites were increased as the initial velocity increases as shown in table and the numerical simulation was developed and combined with academic 3D-AUTODYN v..1software by explicit mesh to calculate time vs. velocity curves and energy absorption of kevlar29/polyester with Al 2 O 3 composite laminated plates. The impact energy absorptions of numerical simulation compared with experimental work which it was 13

15 calculated by using equation (3). The good agreements of the comparisons with maximum errors were.1%. The increasing of thickness of plate affected on the behavior of energy absorption and ballistic limit for the projectile as shown in table that shows the structure obtained of mm thickness was optimum structure to resist the impact loading under 200m/s impact velocity as armor application. Acknowledgement The authors would like to show their appreciation to Universiti Putra Malaysia for supporting the research activity. References [1] Z S Radif, A Ali and K Abdan 2010 Development of a Green Combat Armour from Rame- Kevlar-Polyester Composite vol. 19, no., pp , [2] Marom I and Bonder SR 1979 Projectile perforation of multi-layered beams. int. Journal of Mechanical Sciences, 21:9 [3] Gupta NK, Iqbal MA, and Sekhon GS 2006 Experimental and numerical studies on the behavior of thin aluminum plates subjected to impact by blunt- and hemispherical- nosed projectiles. International Journal of Impact Engineering, 32:1921 [] R Barauskas and A Abraitiene 2007 Computational analysis of impact of a bullet against the multilayer fabrics in LS-DYNA, International Journal of Impact Engineering, vol. 3, no. 7, pp [5] M A Iqbal and N K Gupta 200 Energy absorption characteristics of aluminum plates subjected to projectile impact, Latin American Journal of Solids and Structures, vol. 5, no. July, pp [6] C Defence 2009 A study on the energy dissipation of several different CFRP-based targets completely penetrated by a high velocity projectile PJ Hazell* and G Appleby-Thomas, Composite Structures, vol. 91, pp [7] M. Piggott and B Harris 190 Compression strength of carbon, glass and Kevlar-9 fibre reinforced polyester resins, Journal of Materials Science, vol. 15, no. 10, pp , 190. [] Choi H, Downs R, Chang F 1991 A new approach toward understanding damage mechanisms and mechanics of laminated composites due to low-velocity impact: Part I experiments. J Comp Mater ;25: [9] Choi H, Downs R, Chang F 1991 A new approach toward understanding damage mechanisms and mechanics of laminated composites due to low-velocity impact: Part II analysis. J Comp Mater ;25:10 3. [10] Choi H, Chang F 1992 A model for predicting damage in graphite/epoxy laminated composites resulting from low velocity point impact. J Comp Mater;26(1): [11] AMOTZ WEINBERG and PETER SCHWARTZ 197 Effect of Fibre Volume Fraction on the Strength of Kevlar-29/Epoxy Strands, Journal of Materials Science Letter 6, 13-1 [] M T H Sultan 2007 High Velocity Impact Analysis of Glass-Epoxy Laminated Plates, Ms Thesis, Aerospace Engineering, UPM University, Malaysia. 1