| Ballistic impact mechanism is a very complex mechanical process that mainly depends on different designs,thickness,strength,the density of the target material,and projectile parameters.Fabrics are now being used as a result of the development of strong,high-strength,high-modulus fibers.The goal of this research is to analyze the ballistic resistance of various woven fabric architectures as a function of layer number and inter-yarn friction.Finite element（FE）simulation is used in this study to assess the performance of woven fabrics subjected to ballistic impact with flat-faced cylindrical projectiles at a velocity of 475 m/s.The target in this model is assumed as a square with a side length of 7.54 cm and made by 1,4,8,and 12 layers of the fabric panel and four-side clamped boundary conditions.The model includes two degrees of inter-yarn friction: coefficient of static friction（CSF）and coefficient of kinetic friction（CKF）.Plain,5-end sateen,8-end sateen,11-end sateen,and UD patterns are among the fabric architectures examined.The ballistic performance is analyzed concerning the energy absorption,back-face deformation,and failure mechanism.To begin with,the ballistic performance of the UD fabric,plain fabric,and 5-end sateen fabric of 1-layer,4-layer,8-layer,and 12-layer are investigated.With the increase of inter-yarn friction,the overall energy absorption,kinetic energy,and strain energy of all the three multilayer fabric panels are increased,especially at more layer conditions.However,the frictional dissipation energy just reaches a peak value at the middle inter-yarn friction level.The effect of fabric construction on the overall energy absorption shows such a trend that when both the layer number and inter-yarn friction are much larger,the sateen fabric becomes the best structure at energy absorption.Through stress distribution analyses,all the panels display a similar rule that the layers are much more easily to be broken at lower inter-yarn friction while at the same moment the layers are still intact and share more stress at higher inter-yarn friction.In addition,the stress is much more homogeneously distributed in the remaining layers in the multi-layer sateen fabric panel than in the other two panels.Since the sateen structure is the best,the next work is to investigate the coupling effect of float length,inter-yarn friction,and layer number.With the increase of inter-yarn friction,the energy absorption for all the three float-length sateen fabrics with different layers is significantly increased.For the float length effects,because the larger float length would make the fabric structure much looser,the fabric panel with a larger float length deforms larger.For sateen fabric,it’s not that the longer the floating length,the better ballistic performance would be.Finally,the ballistic energy absorption and failure mechanism of 5-end sateen fabric are analyzed in detail concerning the roles of primary yarns,the roles of each layer in the multilayer system,and the shear stress and tensile stress propagation.To the 5-sateen fabric,it is found that the primary yarns absorb more kinetic and strain energy at the initial impact stage and the secondary yarns account for more kinetic and strain energy at the later impact stage.Moreover,the increase in inter-yarn friction would enhance the role of the primary yarns and secondary yarns and make them absorb more energy.Nevertheless,increase inter-yarn friction brings an unfavorable effect that strengthens the layer in front but weakens the layers at the back.For the failure of the primary yarns,at higher inter-yarn friction,the primary yarns at the front layer take more tensile stress and shear stress but the yarns at the back layers take less. |
