Virtual testing of fabric armor provides an efficient and inexpensive means of systematically studying the influence of various architectural and material parameters on the ballistic impact behavior of woven fabrics, ...Virtual testing of fabric armor provides an efficient and inexpensive means of systematically studying the influence of various architectural and material parameters on the ballistic impact behavior of woven fabrics, before actual laboratory prototypes are woven and destructively tested. In this finite element study, the combined effects of individual ply orientations and material properties on the impact performance of multi-layered, non-stitched woven aramid fabrics are studied using 2-and 4-sided clamping configurations. Individual ply orientations of 0°, ±15°, ±30°, and ±45° are considered along with three levels of inter-yarn friction coefficient. Functionally graded fabric targets are also considered wherein the yarn stiffness progressively increases or decreases through the target thickness while keeping the yarn strain energy density constant and with all other material and architectural parameters unchanged for consistency. For each target configuration, one non-penetrating and one penetrating impact velocity is chosen. The impact performance is evaluated by the time taken to arrest the projectile and the backface deformation for the non-penetrating impacts, and by the residual velocity for the penetrating impact tests. All deterministic impact simulations are performed using LS-DYNA. 2-sided clamped targets and lower inter-yarn frictional levels generally resulted in better impact performance.The functionally graded targets generally showed either similar or inferior impact performance than the baseline fabric target configurations for the non-penetrating shots. Some performance improvements were observed for the penetrating shots when the yarn stiffness was progressively decreased through the layers in a direction away from the strike face, with additional performance enhancements achieved by simultaneously reducing the inter-yarn friction.展开更多
Two Heracron? woven fabrics, HT600-1 and HT600-2, were fabricated with different weaving densities and their resistance to ballistic impact was investigated. While HT600-1 was inherently stronger along the weft than H...Two Heracron? woven fabrics, HT600-1 and HT600-2, were fabricated with different weaving densities and their resistance to ballistic impact was investigated. While HT600-1 was inherently stronger along the weft than HT600-2, the latter exhibited a higher tensile strength along the warp. Crimp values indicate that HT600-1, which possesses a relatively larger weft weaving density, induces an excess in the warp crimp ratio, thereby weakening the fabric along the warp. The dimensionless fiber property U*, which is defined as the product of the specific fiber toughness and the strain wave velocity, was calculated for each fabric. The U* values of HT600-1 were lower than those of HT600-2;U* values along the warp of HT600-1 were extremely low. These analyses show that HT600-2 exhibited improved ballistic properties over those of HT600-1. These findings further indicate the existence of an optimal weave that would minimize damage to both yarn and fabric. Establishing these optimal conditions can be crucial in implementing better ballistic properties into fabrics.展开更多
基金support from the M.C.Gill Composites Center at the University of Southern California(USC)supported by the USC Center for High-Performance Computing(hpcc.usc.edu)
文摘Virtual testing of fabric armor provides an efficient and inexpensive means of systematically studying the influence of various architectural and material parameters on the ballistic impact behavior of woven fabrics, before actual laboratory prototypes are woven and destructively tested. In this finite element study, the combined effects of individual ply orientations and material properties on the impact performance of multi-layered, non-stitched woven aramid fabrics are studied using 2-and 4-sided clamping configurations. Individual ply orientations of 0°, ±15°, ±30°, and ±45° are considered along with three levels of inter-yarn friction coefficient. Functionally graded fabric targets are also considered wherein the yarn stiffness progressively increases or decreases through the target thickness while keeping the yarn strain energy density constant and with all other material and architectural parameters unchanged for consistency. For each target configuration, one non-penetrating and one penetrating impact velocity is chosen. The impact performance is evaluated by the time taken to arrest the projectile and the backface deformation for the non-penetrating impacts, and by the residual velocity for the penetrating impact tests. All deterministic impact simulations are performed using LS-DYNA. 2-sided clamped targets and lower inter-yarn frictional levels generally resulted in better impact performance.The functionally graded targets generally showed either similar or inferior impact performance than the baseline fabric target configurations for the non-penetrating shots. Some performance improvements were observed for the penetrating shots when the yarn stiffness was progressively decreased through the layers in a direction away from the strike face, with additional performance enhancements achieved by simultaneously reducing the inter-yarn friction.
文摘Two Heracron? woven fabrics, HT600-1 and HT600-2, were fabricated with different weaving densities and their resistance to ballistic impact was investigated. While HT600-1 was inherently stronger along the weft than HT600-2, the latter exhibited a higher tensile strength along the warp. Crimp values indicate that HT600-1, which possesses a relatively larger weft weaving density, induces an excess in the warp crimp ratio, thereby weakening the fabric along the warp. The dimensionless fiber property U*, which is defined as the product of the specific fiber toughness and the strain wave velocity, was calculated for each fabric. The U* values of HT600-1 were lower than those of HT600-2;U* values along the warp of HT600-1 were extremely low. These analyses show that HT600-2 exhibited improved ballistic properties over those of HT600-1. These findings further indicate the existence of an optimal weave that would minimize damage to both yarn and fabric. Establishing these optimal conditions can be crucial in implementing better ballistic properties into fabrics.
