Cross-ply unidirectional laminates made of ultra-high molecular weight polyethylene fibers are widely used as components of bullet-proof vests.To simulate the delamination process of the material under penetration,we ...Cross-ply unidirectional laminates made of ultra-high molecular weight polyethylene fibers are widely used as components of bullet-proof vests.To simulate the delamination process of the material under penetration,we constructed a numerical mechanical model,which was validated by tests using 7.6239 mm rifle bullets penetrating laminates of different thicknesses.The results show that the delamination region is essentially diamond-shaped.The simulated delamination region is in good agreement with the experimental data.It is found that the delamination region increases with the compression modulus along the fiber direction.The delamination region increases when the shear strength between the fabric layers decreases;However,it is little influenced by the normal strength.The delamination region of the front face of the laminate is little influenced by the failure strain of the material and the initial velocity of the bullet.The delamination region of the back face increases with the failure strain and decreases with the initial velocity.展开更多
Purpose Terminal performance of a bullet in human body is critical for the treatment of gunshot injury and optimization of bullet design.The effects of the impact velocity(v_(0))and the impact attack angle(δ_(0))of t...Purpose Terminal performance of a bullet in human body is critical for the treatment of gunshot injury and optimization of bullet design.The effects of the impact velocity(v_(0))and the impact attack angle(δ_(0))of the bullet on its terminal performance was investigated,using a new evaluation method(called expansion method)based on the expansion of cracks and the permanent cavity wall in ballistic gelatin.Methods Ballistic gelatin was used to simulate human body.The 7.62 mm×39 mm rifle bullets with different v_(0)(600–76_(0)m/s)andδ_(0)(0°–6°)were fired into the gelatin blocks.The gelatin block was cut into slices of about 2_(0)mm thickness.The cracks and the permanent cavity on each slice were obtained manually.The damaged gelatin was determined using two methods:expanding the permanent cavity but ignoring the cracks,and expanding both the permanent cavity and the cracks.The relations between the damaged gelatin and v_(0)andδ_(0)were obtained using linear fitting method.Results According to the distribution of the damaged gelatin along the penetration depth,the damaged gelatin block could be divided into two parts:the less damaged part and the severely damaged part.The length of the less damaged part depends mostly onδ_(0);while the average damaged area of this part depends on bothδ_(0)as well as v_(0).The cracks contributed significantly to the total volume of damaged gelatin,particularly when the expansion was larger than 1.9 mm.The total damaged gelatin increases with v_(0),δ_(0)and the expansion extent.The average length of equivalent cracks grew with v_(0)andδ_(0)when considering the cracks,and decreased with v_(0)when ignoring the cracks.Conclusion The expansion method is suitable to investigate the influence of different factors of bullets on their terminal performance.The characteristics of the damaged gelatin have a linear relationship with the initial attack angle(δ_(0))and the initial velocity(v_(0))of the bullet.展开更多
基金the Research Foundation for Advanced Talents of Jiangsu University(15JDG038)the Foundation of National Laboratory(601010417)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(19KJB130003).
文摘Cross-ply unidirectional laminates made of ultra-high molecular weight polyethylene fibers are widely used as components of bullet-proof vests.To simulate the delamination process of the material under penetration,we constructed a numerical mechanical model,which was validated by tests using 7.6239 mm rifle bullets penetrating laminates of different thicknesses.The results show that the delamination region is essentially diamond-shaped.The simulated delamination region is in good agreement with the experimental data.It is found that the delamination region increases with the compression modulus along the fiber direction.The delamination region increases when the shear strength between the fabric layers decreases;However,it is little influenced by the normal strength.The delamination region of the front face of the laminate is little influenced by the failure strain of the material and the initial velocity of the bullet.The delamination region of the back face increases with the failure strain and decreases with the initial velocity.
基金Senior Talent Foundation of Jiangsu University(15JDG038)Foundation of National Laboratory(601010417)Natural Science Research of Jiangsu Higher Education Institutions of China(19KJB130003)
文摘Purpose Terminal performance of a bullet in human body is critical for the treatment of gunshot injury and optimization of bullet design.The effects of the impact velocity(v_(0))and the impact attack angle(δ_(0))of the bullet on its terminal performance was investigated,using a new evaluation method(called expansion method)based on the expansion of cracks and the permanent cavity wall in ballistic gelatin.Methods Ballistic gelatin was used to simulate human body.The 7.62 mm×39 mm rifle bullets with different v_(0)(600–76_(0)m/s)andδ_(0)(0°–6°)were fired into the gelatin blocks.The gelatin block was cut into slices of about 2_(0)mm thickness.The cracks and the permanent cavity on each slice were obtained manually.The damaged gelatin was determined using two methods:expanding the permanent cavity but ignoring the cracks,and expanding both the permanent cavity and the cracks.The relations between the damaged gelatin and v_(0)andδ_(0)were obtained using linear fitting method.Results According to the distribution of the damaged gelatin along the penetration depth,the damaged gelatin block could be divided into two parts:the less damaged part and the severely damaged part.The length of the less damaged part depends mostly onδ_(0);while the average damaged area of this part depends on bothδ_(0)as well as v_(0).The cracks contributed significantly to the total volume of damaged gelatin,particularly when the expansion was larger than 1.9 mm.The total damaged gelatin increases with v_(0),δ_(0)and the expansion extent.The average length of equivalent cracks grew with v_(0)andδ_(0)when considering the cracks,and decreased with v_(0)when ignoring the cracks.Conclusion The expansion method is suitable to investigate the influence of different factors of bullets on their terminal performance.The characteristics of the damaged gelatin have a linear relationship with the initial attack angle(δ_(0))and the initial velocity(v_(0))of the bullet.
