Experimental study of transient pressure wave in the behind armor blunt trauma induced by different rifle bullets

Pressure wave plays an important role in the occurrence of behind armor blunt trauma(BABT),and ballistic gelatin is widely used as a surrogate of biological tissue in the research of BABT.Comparison of pressure wave in the gelatin behind armor for different rifle bullets is lacking.The aim of this study was to observe dynamic changes in pressure wave induced by ballistic blunt impact on the armored gelatin block and to compare the effects of bullet type on the parameters of the transient pressure wave.The gelatin blocks protected with National Institute of Justice(NIJ) class III bulletproof armor were shot by three types of rifle bullet with the same level of impact energy.The transient pressure signals at five locations were recorded with pressure sensors and three parameters(maximum pressure,maximum pressure impulse,and the duration of the first positive phase) were determined and discussed.The results indicated that the waveform and the twin peak of transient pressure wave were not related to the bullet type.However,the values of pressure wave's parameters were significantly affected by bullet type.Additionally,the attenuation of pressure amplitude followed the similar law for the three ammunitions.These findings may be helpful to get some insight in the BABT and improve the structure design of bullet.

Influence of impact velocity and impact attack angle of bullets on damage of human tissue surrogate--ballistic gelatin

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.

Dynamic response of armor-piercing bullets to blunt and penetration with protective gelatin

To investigate the coupled damage mechanism of blunt impact and bullets penetration after penetrating ballistic plates against human body targets,experiments were conducted using 6.8 mm caliber armor-piercing bullets against gelatin targets with protective coatings.A numerical analysis model was developed to simulate bullet penetration into gelatin with protective coatings,obtaining endpoint characteristic quantities such as bullet velocity changes,changes in energy distribution,pressure,stress,and stress wave variations within the gelatin target after protection.The results indicate that at a velocity of 640 m·s^(-1),the 6.8 mm caliber armor-piercing round failed to penetrate the ballistic plate yet still caused a blunt impact depression of 37 mm in depth.Under conditions where the bullet did not penetrate the ballistic plate,approximately 80%of the bullet's kinetic energy was absorbed by the ballistic plate.At a velocity of 740 m·s^(-1),the bullet penetrated the ballistic plate,resulting in a blunt impact depression depth of 56 mm and an instantaneous cavity with a maximum diameter of 60 mm.During the process of penetrating the ballistic plate,approximately 50%of the bullet's kinetic energy was absorbed by the ballistic plate,and about 40%of the remaining kinetic energy transferred into the gelatin during the penetration of the target.