eduzhai > Physical Sciences > Materials Sciences >

Evaluation of dynamic properties of composite laminates with energy absorption

  • sky
  • (0) Download
  • 20211030
  • Save
https://www.eduzhai.net International Journal of Composite M aterials 2013, 3(3): 73-82 DOI: 10.5923/j.cmaterials.20130303.06 Assessment of Dynamic Behavior for Composite Laminate with Respect to the Absorbed Energy Basim M. Fadhil Petroleum EngineeringDepartment, Koya University, Erbil, 964, Iraq Abstract The aim of this study is to evaluate and comparing the absorbed energy for two different co mposite materials. Glass-epoxy and Kevlar-epo xy laminates with four d ifferent thicknesses are backed with thin alu minum plates have been subjected to high velocity impact by two different nosed impactors. 3D –fin ite element modeling has been used to simulate the impact event by ANSYS-AUTODYN co mmercial hydrocode. It has been found that the absorbed energy is strongly affected by the composite materia l type besides the impactor nose and there is no important effect of the packed metal plates e on the absorbed energy by the composite laminate. Keywords Absorbed Energy , Co mposite , Impact Loading 1. Introduction There is steady increase in the nu mber of applicat ions polymer matrix co mposite materials especially in military vehicles, marine vessels and aerospace structures[1]. These structures are subjected(oftentimes) to very high stresses or damage fro m h igh-velocity projectiles. In a composite materials subjected to high strain rate loading (ballistic impact),with specific mechanis ms the kinetic energy of the projectile will dissipated. The prevalent mechanisms of energy absorption are: kinetic energy transmitted to the target, cone format ion on the rear side o f the target and/or spall formation, energy absorption as a result of shear plugging, fiber failure of the p rimary yarns by tension, fiber debonding, fiber pull-out, elastic deformation of the secondary yarns, matrix cracking, interlaminar delamination, and frictional energy absorbed during interaction of the penetrator and laminate[2–4]. through the last several decade, large nu mber of works have concentrated on theoretical and experimental research on the transverse impact response of polymer matrix co mposite laminates in order to get view into failure mechanis ms and energy absorption. Bulk of the work to date has focused on thermoset composites[5–8] or high-functioning thermoplastic co mposites[9]. Perforation and penet rat ion of fiber reinfo rced p lastic lamin ates us ing d ifferent n o s ed project ile shapes, e.g. semi-h emispherical, co n ical, og ive, and flat has been in vest igat ed . An analyt ical mod els based on mat erial chacteristics and the static punch curve for various nosed * Corresponding author: basim.fadhil@koyauniversity.org (Basim M. Fadhil) Published online at https://www.eduzhai.net Copyright © 2013 Scientific & Academic Publishing. All Rights Reserved projectiles in o rder to predict the ballistic limit proposed in this work[10, 11]. An evaluation of the dynamic penetration of Carbon Fiber Reinforced Plastic (CFRP) co mposites for a velocity range of 21- 91 m s-1 for a flat-end cylindrical pro jectile was experimentally investigated[7]. It ’s found that the penetration occurs in three obvious stages: fiber crushing ( pre-delamination), post-delamination before plugging, and post- plugging. The ballistic impact of monolithic fiber reinforced co mposite laminates was studied[12], where has been found that the contact force is strongly dependent on the projectile mass, but with no effect on the amount of the absorbed energy, also dependent on the kinetic energy of the impactor. A high velocity impact response of composite laminates with three different types of reinforcements; glass, aramid and polyethylene fiber has been investigated[13]. It has been found that the delamination had a major part of the energy, where thickness dependence on the impact response of glass fiber reinforced laminates, Also it is found that the indentation phase is most significant[14]. The failure by tension of primary yarns and secondary yarns deformation are the main co mponents mechanisms of the energy absorption. The primary yarns are those in contact with the impactor whereas secondary yarns are those displaced by the deformation of the primary yarns[15]. An important number of work has concentrated on modeling mechanisms of failure for laminated polymer matrix co mposites subjected to transverse impact loading wh ere agreed that composites fail in a progressive mode[16]. Damage mechanics technique used to define matrix cracking and fiber/ matrix delamination by introducing damage variables associated with materia l stiffness reduction in their plasticity model. a nu merical method reported[17] to predict 74 Basim M . Fadhil: Assessment of Dynamic Behavior For Composite Laminate with Respect to the Absorbed Energy composite damage using Continuum Damage Mechanics (CDM) using the framewo rk outlined by[18] . The objective of this wo rk is to investigate the impact response of two types of nosed projectiles (flat and hemispherical) on glass/epoxy and Kevlar-epo xy laminate with four different thicknesses (1.2, 2.4, 3.6, and 4.8 mm) covered by t wo Aluminu m p lates with 0.7 mm thickness for each plate, by studying the influence of projectile nose, composite materials type and thickness, and metal materials on energy absorption and compare the founded results. A d EDi EDLi EFi Emt EMCi EKEi ESP i ET Fi ET OTALi Fi h KEop KEpi MCi t Vf Nomen clat ure cross-sectional area of fibre/yarn projectile diameter energy absorbed by deformation of secondary yarns till time (ti ) energy absorbed by delamination till time (ti ) energy absorbed by friction till time (ti) energy absorbed by matrix cracking per unit volume energy absorbed by matrix cracking till time (ti ) kinetic energy of the moving cone at time (ti ) energy absorbed by shear plugging till time (ti ) energy absorbed by tension in primary yarns tilltime (ti ) total energy absorbed by the target till time (ti ) contact force during ith time interval target thickness initial kinetic energy of the projectile kinetic energy of the projectile at time (ti ) mass of the cone at t ime (t i ) duration of time interval fibre volume fraction Greek letters ε st rain ε0 maximum strain in a yarn/fibreat any moment εd damage threshold strain εi maximum tensile strain in primary yarns at time(ti) εp plastic strain εpy strain in primary yarns εsy strain in secondary yarns ρ density of the target σ st ress σsy stress in secondary yarns 2. Damage Mechanism Basically, the ballistic impact is a low-mass high-velocity impact by a projectile against target event. So, the influences on the target can be just near the position of impact. During the impact event, energy transfer occur fro m the impactor to the target. Depends on the target shape (geometry), material properties and impactor parameters the following are p o ss ib le. 1. If the impactor (pro jectile) perforates the target and exits with a certain residual velocity, this refer that the absorbed energy by the target was less than the initial kinetic energy of the impactor. 2. If the target was partially penetrated by the impactor. this refer that the projectile init ial kinetic energy was less than the energy that the target can absorb. Depends on the target materia l properties, the impactor can either be rebound or stuck within the target. 3. If the target comp letely perfo rated with zero impactor exit velocity. For such a case, the entire kinetic energy of the projectile is just absorbed by the target. 3. Analytical Model At target strikes, the impactor energy is absorbed by many mechanis ms like kinetic energy of the moving cone EKE, shear plugging ESP, deformation of secondary yarns ED, tension in primary yarns ETF, delamination EDL, matrix cracking EMC, frictional energy EF along with other energy dissipation mechanisms. Here, an analytical model is presented for the above-mentioned mechanisms, which dominate during ballistic impact of two-dimensional woven fabric co mposites[19]. During the ballistic impact event, delamination and mat rix cracking take place in the laminate area, wh ich forms the cone Figure(1). The total kinetic energy of the projectile that is lost during ballistic impact is the total energy that is absorbed by the target till that time interval and is given by, ????????TOTAL???????? = ????????KE???????? + ????????SP???????? + ????????D???????? + ????????TF???????? + ????????DL???????? + ????????MC???????? + ????????F???????? (1) The first time interval of impact event, Total energy is a kinetic energy of the impactor. then, this energy is transferred into energy absorbed by many damage mechanis ms and the kinetic energy of moving cone and projectile. Considering the energy balance at the end of ith time interval, KEP0 = KEp???????? + ????????KE + ????????SP(???????? − 1) + ED(???????? − 1) + ????????TF + ????????DL(???????? − 1) + ????????MC(???????? − 1) + ????????F(???????? − 1) (2) Where ???????????????? − 1 = ????????SP (???????? − 1) + ????????D (???????? − 1) + ????????TF(???????? − 1) + ????????DL(???????? − 1) + ????????MC(???????? − 1) + ????????F(???????? − 1) So the energy of the cone formed at the end of ith time interval is, ???????????????????????????????? = 1 2 ???????????????????????? ????????????????2 (3) The energy absorbed by shear plugging by the end of ith time interval is given by, ???????????????????????????????? = ∑???????????????? =???????? =0 ∆???????????????????????????????? (4) The energy absorbed in the deformation of all the secondary yarns can be obtained by the following integration[20], ???????????????????????? = ∫????????????????????????(∫0∈???????????????????????? ???????????????????????? √2 �???????????????????????? �????????∈???????????????? ????????ℎ{2???????????????? − 8???????????????????????????????? −1 ( ???????? 2???????? )}???????????????? (5) When the strain in yarns/fibres exceeds failure strain, it fails and some energy is absorbed due to tensile fa ilure . For a yarn/fibre of cross-section area A it is given by, ???????????????????????? = ???????? ∫0???????? (∫∈∈==0∈???????????????????????? /2 ???????? (∈)????????????????)???????????????? (6) where ε0 is the ultimate strain limit. If during ith time interval N numbers of yarns/fibres are failing, then the right hand side International Journal of Composite M aterials 2013, 3(3): 73-82 75 of the above expression is mult iplied by N.So the respective energies absorbed by delamination and matrix cracking during this time interval are given by, ???????????????????????????????? = ∑???????????????? =???????? =1 ∆???????????????????????????????????????? (7) ???????????????????????????????? = ∑???????????????? =???????? =1 ∆???????????????????????????????? (8) impactors are 9 mm in diameter, with 14.48 and 12.76 mm length for the flat nose and hemispherical nose projectile respectively with 4.45E5 mJ initial kinetic energy, this difference in length is to maintain the volu me constancy and to keep the mass equal to 7.17 gram for pro jectiles types (Figure ). The target is 200 x 200 mm panel and consist of systems, each o f them has three parts; upper metal plate(alu minu m 2024-T4) with 0.7 mm intermed iate glass-epoxy laminate (or Kev lar epo xy laminate) and lower metal p late (alu minu m 2024-T4) with0.7 mm. Both targets and the projectile are modeled with uniform hexahedron solid elements. Due to the symmetric nature of the impact system, on ly one half of the projectile target system is modeled here. (Figures3) and 4) for pro jectile and targets a Lagrange solver was used. The impactor (copper) and all target materials properties have been used from ANSYSAUTODYN hydrocode lib rary. (a) Figure 1. Conical deformation during ballistic impact on the back face of the composite target 4. Numerical Model (b) Figure 2. Finite element model ,(a) with Flat nosed Impactor, (b) with hemi-spherical nosed impactor A 3D finite element model of impact system has been built by A NSYS-AUTODYN co mmercial hydrocode. This impact system consists of normal impact of hemispherical and cylindrical copper impactor onto target. The copper 5. Results and Discussions 5.1. Abs orbed Energy by Kevler– Epoxy Laminate (Internal Energy) Int.Energy (mJ) 1.2 mm keve 45000 40000 35000 30000 25000 20000 15000 10000 5000 0 Flat Nosed Impactor Hemi-Spheric lNosed Impactor 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 Time (m sec.) Int. Energy (mJ) kev int. 2.4 mm Flat Nosed Impactor 80000 Hemi- Spherical Nosed Impactor 60000 40000 20000 0 0 0.02 0.04 0.06 0.08 0.1 Time (m sec.) (a) (b) 3.6 k int.3.6 mm Flat Nosed Impactor 100000 Semi- Spherical Nosed Impactor 4.8 k int Flat Nosed Impactor 150000 Hemi-SphericalNosed Impactor Int.energy (mJ) Int.Energy (mJ) 80000 60000 40000 20000 0 120000 90000 60000 30000 0 0.02 0.04 0.06 0.08 0.1 0.12 0 Time (m sec.) ( c) 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 Time (m sec.) (d) Figure 3. Internal energy vs. time for different thicknesses(Kevlar–epoxy ),(a) 1.2mm thickness,(b) 2.4 mm thickness.,( c) 3.6 mm thickness.,(d) 4.8mm thickness 76 Basim M . Fadhil: Assessment of Dynamic Behavior For Composite Laminate with Respect to the Absorbed Energy The Figure 3.(a , b, c, and D) shows the internal energy vs. time for different thicknesses (1.2,2.4,3.6,and 4.8 mm) of kevlar –epo xy layer with flat and Hemi-spherical nosed impactor. all these figures indicates the increase of internal energy for certain value of impact time followed by settle down after that. In general ,the absorbed internal energy increases with increase layer thickness with the notice that the kevlar-ep xoy laminate absorbs energy with flat nosed impactor mo re than semi-spherical one especially for thicknesses 1.2,2.4 and 3.6 mm. 5.2. Abs orbed Energy by Gl ass-Epoxy Laminate (Internal energy) Generally ,the behavior of glass –epoxy laminate with the two different nose impactor is the same of the previous one ,where the internal energy increase with time ,but with flat nosed impactor the internal energy increases smoothly with t ime especially for 1.2,2.4, and 3.6 mm thicknesses, while there is a peak point follo wed by suddenly decline of the internal energy for the thicknesses 1.2, 2.4,and 3.6 mm. in addition ,for flat and semi-spherical nosed impactor ,the internal energy that absorbed by Kevlar –epo xy layer Start close to each other with a small increase for the benefit of semi-spherical nosed impactor and especially for thicknesses 1. 2, 2. 4 mm .But the situation changes when the thickness 3. 6,and 4.8mm where the d ifference starts in the values of the absorbed internal energy to become more ith flat nosed impactor.see Figure 4(a, b, c, and d). Int.Energy (mJ) 1.2 glass int Flat Nosed Impactor 15000 Hemi- Spherical Nosed Impactor 12000 9000 6000 3000 0 0 0.02 0.04 0.06 0.08 0.1 0.12 Time (m sec.) (a) 2.4 gl int Flat Nosed Impactor Hemi-SphericalNosed impactor 25000 Int.Energy (mJ) 20000 15000 10000 5000 0 0 0.02 0.04 0.06 0.08 0.1 Time (m sec.) (b) 3.6 glass int Flat Nosed Impactor 40000 Hemi-Spherical Nosed Impactor Int.energy (mJ) 30000 20000 10000 0 0 0.02 0.04 0.06 0.08 Time (m sec.) (c ) 4.8 glass int Flat Nosed Impactor Hemi-Spherical Nosed Impactor 50000 Int.Energy (mJ) 40000 30000 20000 10000 0 0 0.02 0.04 0.06 0.08 Time (m sec.) (d) Figure 4. Internal energy vs. time for different thicknesses(glass–epoxy ),(a) 1.2mm thickness,(b) 2.4 mm thickness.,( c) 3.6 mm thickness.,(d) 4.8mm thickness The figure 5 illustrates the relation between lamionate thickness and the absorbed energy ( internal energy) ,apparently ,there is an increases of internal energy with increasing layer thickness especially for kevlar –epoxy material with notice that ,there is a considerable difference in the internal energies with flat and spherical nosed impactor begin at 1.2 mm ended at 3.6 reaching equal value(appro ximately) at 4.8 with slightly value for the benefit of spherical nosed impactor. whereas there is a slightly increases of internal energy of glass-epoxy materia l with thic kness and the difference of this energy with the two types of impactor not little importance especially for 1.2and 2.4 mm th icknesses, but with 3.6 and 4.8 mm litt le difference appear of internal energies with flat nosed impactor in contrast of previous case (Kevlar-epo xy). International Journal of Composite M aterials 2013, 3(3): 73-82 77 Int.Energy (mJ) glass-Epoxy withFlat .Impactor Glass-Epxy With Hemi-Sph .Impactor 150000 Kevl-Epoxy with Flat Impactor Kev-Epoxy with Hemi-Sph. Impactor 120000 90000 60000 30000 0 0 1 2 3 4 5 6 Thickness (mm) Figure 5. Absorbed energy vsthickness laminate 5.3. Nose Impactor Type And Internal Energy of Metal Plate (Withglass-Epoxylami nate) The figure 6 shows that the internal energy amount of Al plate is strongly affected by the plate position (upper or lo wer) and the type of impactor (nose),where we can notice that lower p late (with flat nose impactor) has the highest value of internal energy (except at th ickness 4.8 mm) followed by upper plate with spherical nose , upper plate with flat nose and finally by lower plate with spherical nose impactor Int.Energy (mJ) Upper Al Plate with Flat Impactor Upper Al Plate withHemi-Sph. Impactor Lower Al Plate with Flat Impactor Lower Al Plate with Hemi-Sph. Impactor 30000 25000 20000 15000 10000 5000 0 0 1 2 3 4 5 6 Thickness (mm) Figure 6. Absorbed energy vs packed metal plate thickness Internal Energy (mJ) with kevla7r 0000 60000 50000 40000 30000 20000 10000 0 0 2 4 6 Thickness (mm) Upper Al plate with Flat Impactor Al Lower Plate with Falt Impactor Upper Al plate with Hemi-Spherical Impactor Al lower plate with Hmei- Spherical Impactor Figure 7. Absorbed energy vs packed metal plate thickness 5.4. Nose Impactor type and internal Energy of Metal Plate (With Kevl ar-Epoxy laminate) Here again (Figure 7) the composites layer (Kevlar- epoxy ) and the impactor nose type play a very significant role for the amount of absorbed energy by the alu minu m plate, where the lower p late with flat nose impactor has the highest value of internal energy wh ile the upper plate with flat nose impactor has the lowest value of internal energy. in addition that the thickness of kevlar epo xy layer has no big influence on the internal energy of upper metal p late (alu minu m) with the t wo types of impactors. But there is an important effect of the Kevlar epo xy thickness on the internal energy for the lower plate with semi-spherical nose impactor ,where we can see a linear increasing of internal energy with Kevlar epo xy layer.So ,we have a co mplicated relationships between location of metal plates and composites material thickness besides the shape of impactor nose, but it is clear that the 78 Basim M . Fadhil: Assessment of Dynamic Behavior For Composite Laminate with Respect to the Absorbed Energy lower plate absorbs energy more than the uppers one . 5.5. Internal Energy Increase with Thickness Increase Relati onshi p 5.5.1. Kevlar Epo xy Laminate It is very clear fro m figure 8 that doubling the thickness leads to increasing of the internal energy approximately four times and by almost within linear relat ionship for semi-spherical nosed impactor, wh ile there is a slightly increases in the internal energy with cylindrical impactor (flat nose). kev Flat Nosed Impactor Hemi-Spherical Nosed Impactor 15 Int.Energy Increases ( Times) 10 5 0 0 1 2 3 4 5 Thickness Increases (Times) Figure 8. absorbed energy increase (times) vsThickness Increases (times) for Kevlar -epoxy 5.5.2. Glass-epoxy Laminate With galss-epxoy materia l ,the doupling of it thickness the internal energy will increases but not more 4.5 times comparing with13.2 t imes for kevlar epo xy layer,also with flat nosed impacto(cylinder) the doubling of intarnal energy was more than that with semi-spherical nosed mpactor with notice that there is an increases for internal energy with both of impactors. Fro m figure 9 we can see that the internal energy ratio (with flat nosed impactor /semi-spherical nosed impactor) be at maximu m for kevlar epo xy material and at 1.2 mm thickness and this ratio decrease with increase thickness ,while for glass epoxy material this ratio was almost constant. g Flat Nosed Impctor Hemi-Spherica lNosed Impactor 5 Int.Energy Increaes (Times) 4 3 2 1 0 0 1 2 3 4 5 Thickness Increaes (Times) Fi gure 9. Absorbed energy increase (t imes) vs Thickness Increases (t imes) for glass-epoxy Fro m figure 10 we can see that the internal energy ratio (with flat nosed impactor /semi-spherical nosed impactor) be at maximu m for kev lar epoxy material and at 1.2 mm thickness and this ratio decrease with increase thickness ,while for glass epoxy material this ratio was almost constant. inter,energy Kevlar -epoxy Glass -epoxy 5 Int. Energy with Flat Nosed Impactor/Int. Energy with Spherical Nosed Impactor 4 3 2 1 0 1.2 2.4 3.6 4.8 Composite Matreial Thickness (mm) Figure 10. Absorbed energy ratio vs composite thickness (for both impactors) 5.6. Ki netic Energy 5.6.1. With Glass Epo xy Laminate The Fig.11 shows the relationship between the residual to initial kinetic energy rat io versus glass epoxy laminae thickness with the two different nosed impactor. It is very clear that The kinetic energy ratios slightly decreases with increase the glass epoxy co mposite thickness .And there is no big difference between the two ratios for all thicknesses. Kin.Energy Ratio(residual/ Initial) glass-epoxy Falt Nosed Impactor Hemi-Spherical Nosed Impactor 1 0.8 0.6 0.4 0.2 0 1.2 2.4 3.6 4.8 Thickness (mm) Figure 11. Kinetic energy ratio vs composite thickness (for both impactors) 5.6.2. With Kev lar –epo xy laminate International Journal of Composite M aterials 2013, 3(3): 73-82 79 Fro m figure 12, apparently that; first: kinetic energy ratio decreases with increase the Kevlar epo xy laminate thickness. Second: the rat io with hemi-spherical impactor. Th ird: the d ifference between the t wo ratios decreases with increases kevaler-po xy laminate thickness. Kin.Enrgy Ratio (Residual/Initial) kev Flat Nosed Impactor Hemi-Spherical Nosed Impactor 1 0.8 0.6 0.4 0.2 0 1.2 2.4 3.6 4.8 Thickness (mm) Fi gure 12. Kinet ic energy rat io vs composite thickness (for both impactors) 5.6.3. For Flat Nosed Impactor Obviously, the ( residual/ initial) kinetic energy ratio decreases with Kevlar–epo xy laminate thickness increase while slightly decreases for glass-epoxy laminate. Th is ratio is less for kevalr –epo xy than that for glass-epoxy Figure 13. Cyl impactor 1 Glass-Epoxy Kev-Epoxy Kin.Energy Ratio (Residual/Initial) 0.8 0.6 0.4 0.2 0 1.2 2.4 3.6 4.8 Thickness (mm) Figure 13. Kinetic energy ratio vs composite thickness (for flat nosed impactor) 5.6.4. For Hemi-spherical Nosed Impactor With Hemi-spherical Nosed Impactor the (residual /in itial ) kinetic Energy rat io for kevlar-epo xy laminate decreases with laminate thickness very clearly fro m the previous case ,while for glass epoxy laminate is still the least well here. Sph impactor Glass-Epoxy Kev-Epoxy 1 Kin.Energy Ratio (Residual/Initial) 0.8 0.6 0.4 0.2 0 1.2 2.4 3.6 4.8 Thickness (mm) Figure 14. Kinetic energy ratio vs composite thickness (for hemi-spherical nosed impactor) With Hemi-spherical Nosed Impactor the (residual /in itial ) kinetic Energy rat io for kevlar-epo xy laminate decreases with laminate thickness very clearly fro m the previous case ,while for glass epoxy laminate is still the least well here. 5.7. Image Anal ysis 5.7.1. With Glass-Epo xy Laminate The figure 15 illustrate the status of the target after the impactor departure fro m the rear side for the four different thicknesses. Obviously the upper metal plate and the glass epoxy laminate are subjected to shear plugging then perforation 80 Basim M . Fadhil: Assessment of Dynamic Behavior For Composite Laminate with Respect to the Absorbed Energy only, wh ile the rear metal plate one suffered dishing and perfo ration. The behavior of target system almost similar for both types of impactor with slightly difference . 1.2 mm laminate thickness 1.2 mm laminate thickness 2.4 mm laminate thickness 2.4 mm laminate thickness 3.6 mm laminate thickness 3.6 mm laminate thickness 4.8 mm laminate thickness 4.8 mm laminate thickness Hemi-spherical nosed Impactor Flat nosed Impactor Glass epoxy laminate Figure 15. Damage behavior for different thicknesses for glass epoxy laminate 5.7.2. With Kev lar-Epo xy Laminate The figure 16indicates the status of the target after the impactor departure fro m the rear side of the target system for the four different thicknesses. Herein the difference of the target behavior system under impact load with the flat and hemispherical nosed impactor is clear especially at the 1.2 mm thickness of Kevlar epo xy laminate wh ile this difference decreases with increase thickness of the laminate . International Journal of Composite M aterials 2013, 3(3): 73-82 81 1.2 mm laminate thickness 2.4 mm laminate thickness 3.6 mm laminate thickness 1.2 mm laminate thickness 2.4 mm laminate thickness 3.6 mm laminate thickness 4.8 mm laminate thickness 4.8 mm laminate thickness Flat nosed impactor Hemi-spherical impactor Kevlar epo xy laminate Figure 16. Damage behavior for different thicknesses for Kelar- epoxy laminate 6. Conclusions The laminate type , laminate thickness, and impactor nose are playing a very significant role of impact behavior besides the amount of absorbed energy. We concluded the following : For absorbed energy: 1. The energy absorbed by the upper metal p late does not affected by either impactor nose type nor laminate type 2.The energy absorbed by the lower metal plate with flat nosed impactor was higher than that for hemi-spherical one. 3. The energy absorbed by lower metal plates increases with laminate thickness while for upper plate there is no significantly increased with laminate thickness for hemispherical nosed impactor. 4. The backed metal p lates(upper and lower) have no effect on the absorbed energy by the composite laminate. 5. For kevlar- epo xy laminate. ● The absorbed energy increases with increase laminate th ickn es s . ● The amount of energy absorbed with flat nosed impactor is higher than that with hemispherical one . 82 Basim M . Fadhil: Assessment of Dynamic Behavior For Composite Laminate with Respect to the Absorbed Energy ● The doubling times of absorbed energy increases strongly with doubling times of laminate thickness for flat nosed impactor, wh ile very lo w with hemispherical one. 6. For kevlar- epo xy laminat. ● The absorbed energy increases with increase laminate th ickn es s . ● Here again he amount of energy absorbed with flat ● nosed impactor is h igher than that with hemispherical one . The doubling times of absorbed energy increases strongly with doubling times of laminate thickness for flat nosed impactor and for he mispherical one For kinetic Energy: 1) The residual kinetic energy decreases with increase laminate thickness. 2) The residual kinetic energy for flat nosed impactor is less than that for hemispherical one. 3) The residual kinetic energy for both impactors with Kevlar –epoxy laminate is less than that for Glass–epoxy la minate. [7] G. Zhu, W. Goldsmith, CKH. Dharan,” Penetration of laminated Kevlar by projectiles—I. Experimental investigation,” Int J Solids Struct,29(4):399. 1992. [8] G. Zhu, W. Goldsmith, CKH. Dharan,” Penetration of laminated Kevlar by projectiles—II. Experimental investigation,” Int. J. Solids Struct.,29(4):421. 1992. [9] AC. Okafor, AW. Otieno, A Dutta, VS Rao,” Detection and characterization of high-velocity impact damage in advanced composite plates using multi-sensing techniques,” Compos. Struct.Vol. 54, Issues 2–3, 289–297. 2001. [10] HM . Wen,”.Predicting the penetration and perforation of FRP laminates struck normally by projectiles with different nose shapes,”. Compos. Struct. 49:321. 2000. [11] HM . Wen,” Penetration and perforation of thick FRP laminates,” Compos. Sci. Technol 61:1163. 2001 [12] E. Wu, LC. Chang,”Woven glass/epoxy laminates subject to projectile impact,”.Int. Impact Eng.16(4):607–19. 1995. [13] M ines RAW, AN. Roach, N. Jones,” High velocity perforation behaviour of polymer composite laminates,". Int. J. Impact Eng .22(6):561–88. 1999. REFERENCES [14] EP. Gellert, SJ. Cimpoeru, Woodward,” RLA study of the effect of target thickness on the ballistic perforation of glass-fibre-reinforced plastic composites,” Int. J. Impact Eng.24(5):445–56. 2000. [1] S. Abrate, . Impact on composite structures.. Cambridge [15] NK. Naik, P. Shriaro,”Composite structures under ballistic University Press, Cambridge, UK. 1998 impact,”. Compos. Struct. 66(1–4).579–90. 2004 [2] CT. Sun, SV. Potti,” A simple model to predict residual [16] Z. Guan, C. Yang,” Low-velocity impact and impact process velocities of thick composite laminates subjected to high of composite laminates,” J. Compos. M ater .36(7):851–71. velocity impact,” Int. J Impact Eng 18(3):339. 1996. 2002. [3] SS. M orye, PJ. Hine, RA Duckett , DJ Carr, IM Ward , [17] Z, Hashin,” Failure criteria for unidirectional fiber “M odelling of the energy absorption by polymer composites composites,” J. Appl. M ech. 47(2):329–35. 1980. upon ballistic impact,” Compos. Sci Technol 60. 2631. 2000. [18] M . Grujicic, B. Pandurangan, KL. Koudela,BA Cheeseman,” [4] Department of Defense Test M ethod Standard V50 Ballistic A computational analysis of the ballistic performance of Test for Armor, M IL-STD-662F. (1997) light-weight hybrid composite armors,” Appl. [5] RAW. M ines, AM . Roach, N Jones,” High velocity Surf.Sci.253(2):730–45. 2006. perforation behaviour of polymer composite laminates,” Int. J [19] N.K. Naik, P. Shr irao,”Composite structures under ballistic Impact Eng 22:561. 1999. impact,” Compos. Struct. 66 . 579. 2004. [6] Lee SWR, CT Sun,”Dynamic penetration of graphite/epoxy laminates impacted by a blunt-ended projectile,” Compos Sci Technol 49:369. 1993. [20] N.K. Naik, P. Shrirao, B.C.K. Reddy,”Ballistic impact behaviour of woven fabric composites: Formulation,: Int. J. Impact Eng, Vol. 32, 9. 1521–1552. 2006.

... pages left unread,continue reading

Document pages: 10 pages

Please select stars to rate!

         

0 comments Sign in to leave a comment.

    Data loading, please wait...
×