Kinetic energy less lethal weapons and their associated blunt trauma injuries

Abstract

A widely used class of Less Lethal Weapon is the kinetic energy projectile. This can cause blunt trauma to the targeted person and, under certain circumstances, its use can result in permanent injury or death. The low velocity at which Less Lethal projectiles are launched results in inaccuracy of use thus increasing the possibility that non targeted areas of the body susceptible to injury by blunt trauma will be hit. This research has been focused to investigate the impact characteristics of kinetic energy Less Lethal projectiles using different masses, materials, geometries and impact velocities and how they affect the criteria for injury to the head and the thorax.

Computer based models for simulating impacts and possible injuries were investigated. Hydro codes were used to predict the effect of a range of projectile masses and impact velocities for a simplified human target. Physical models were built and tested to compare with the computer predictions. A correlation between projectile mass, velocity and skin penetration was found.

Research was carried out on the impact process using an instrumented projectile to measure the acceleration experienced by the projectile and the duration of acceleration for a range of target materials. A simulated head model with a displacement transducer was used to investigate the impact properties of a range of projectile geometries with the objective of identifying the probable effect on blunt trauma and the level of injury that may be sustained. The introduction of air cavities into the projectile reduced the recorded displacement as well as its acceleration whilst extending the duration of the impact.

High-speed video was used to investigate the impact process between the projectile and the target using a simulated thorax. The target used was a Behind Armour Blunt Trauma (BABT) test rig originally developed to investigate behind armour blunt trauma associated with combat body armour impacted by high velocity projectiles. A wide range of projectile geometries, materials and masses were investigated to examine the probable effect on blunt trauma and the level of injury that may be sustained. The introduction of air cavities and reduction of projectile mass was found to slightly reduce the rate of displacement in the BABT rig; however the maximum displacement remained similar because of the similar masses and velocities involved.