Numerical study of the dynamic expansion behaviour of 9 mm expansion bullets in gelatine

Low-velocity nail penetration response of muscle tissue and gelatin

Quantitative estimation of soft tissue injuries due to penetration of sharp objects is a challenging task for forensic pathologists. The severity of injury depends on the force required to penetrate the tissue. This study focuses on investigating the amount of force required to penetrate porcine muscle tissue and gelatin simulants (10 % wt) to mimic human muscle tissue when subjected to sharp objects like nail at velocities below 5 m/s. A custom-made experimental setup was used to examine the influence of penetration velocity and nail diameter on penetration forces. Images captured by a high-speed camera were used to track the position and velocity of the nail. A finite element (FE) model was established to simulate the penetration behavior of the tissue and gelatin. The FE simulations of the nail penetration were validated through direct comparison with the experimental results. In tissues as well as in the simulant, penetration forces were seen to increase with increasing nail diameter and velocity. Porcine muscle tissue showed 23.9-46.5 % higher penetration forces than gelatin simulants (10 % wt) depending on nail diameter and velocity; the difference being higher for higher nail diameter and velocity. The ranges of maximum penetration forces measured were 8.6-59.1 N for porcine muscle tissue and 6.8-34.9 N for gelatin simulant. This study helps to quantify injuries caused by sharp nails at low velocities and offers insights with potential applications in injury management strategies and forensic studies.

The effects of certain intermediary target materials and their proximity to ballistic gelatin on jacketed hollow point bullet expansion

Expanding bullets are preferred by law enforcement because of their wounding potential and ability to avoid over-penetration which could result in unintended targets being struck by bullets that perforate their intended targets. Expansion failure for jacketed hollow point (JHP) bullets is commonly attributed to several causes including damage to the bullet's cavity, velocity loss, bullet destabilization and materials from intermediate targets filling the bullet's cavity which can cause expansion failure when the bullet subsequently impacts a soft, fluid-based target such as human tissue or ballistic gelatin. In this study, JHP bullets were fired into ballistic gelatin after passing through selected intermediate targets representing items common to shooting incidents. Velocity loss and bullet destabilization were not factors that contributed to the JHP bullets that experienced expansion failure; however, materials obstructing the bullets' cavities and damage to the bullets' cavities were considered causes for some of the JHP bullet expansion failures. It was determined through this research that most of the target materials caused JHP bullet expansion failure when shored against the ballistic gelatin, but when placed at distances of 7 ft. from the ballistic gelatin, bullets fired through the same target materials did expand. This original and unique study produced findings that are of significant value to shooting incident reconstruction experts and other forensic professionals as shooting incidents can call into question a victim's proximity to a wall or door when a bullet(s) perforated such a target material.

Lagrangian approach embed with discrete element method for extreme deformation study in frangible bullet designs fragmentation and penetration on viscoelastic ballistic gel

Development of a model for analyzing a bullet's impact is important in the military field to design a bullet with desired properties. This study uses a finite element model with a Lagrangian framework and Lagrange-discrete element method (DEM) model by ANSYS Explicit Dynamic to investigate the effect of frangible bullet designs on bullet deformation and penetration in ballistic gel setting. A modeling approach with ballistic gel can analyzed the extreme deformation of bullets much faster compared to the more resource intensive real life ballistic gel test. The study starts with developing a 3D model, then importing it to an ANSYS workbench to solve the problems. Overall, the results of Lagrange-DEM shows deeper penetration and better accuracy to represent the real life ballistic gel test than other simulation method. The fluted bullet design has a shorter penetration depth but a bigger temporary cavity diameter than the flat-nosed one due to its notch and asymmetrical design, which becomes the part that is easily deformed and leads to directional deformation.

Bullet Frangibility Factor Quantification by Using Explicit Dynamic Simulation Method

Frangible bullets have a unique property that disintegrates into fragments upon hitting a hard target or obstacle. This peculiar ability to become fragments after impact is called frangibility. In this study, frangibility testing was carried out theoretically via modeling using the explicit dynamics method with ANSYS Autodyn solver integrated by ANSYS Workbench software. This paper aims to analyze frangibility through two main factors: material properties and projectile design. The results show the scattering and remaining bullet fragments after impact. According to the modeling results, the frangibility factor values are 9.34 and 10.79, respectively. Based on the frangibility factor, errors based on the frangibility factor by comparing the experimental results and simulations for AMMO 1 and AMMO 2 are 10.5% and 1.09%. Based on simulation results, the AMMO 2 design bullet scattering pattern shows several scattering particles more than the AMMO 1 design, with the furthest distance scattering AMMO 1 and AMMO 2 bullets being 1.01 m and 2658 m.