Projectile deformation on human bone and on a polyurethane simulant

Polyurethane bone simulants are often used in ballistic experiments, within a forensic and medico-legal context and elsewhere. This study compared the degree of deformation of projectiles fired at human bone to projectiles fired at a polyurethane bone simulant. Ductile 5.5 mm spheres were propelled with a mean velocity of 279 m/s and fired at both freshly embalmed human cranial bone samples and at polyurethane bone simulant samples. The spheres deformed more when perforating the human samples than when perforating the polyurethane samples. As a result, it is questionable to use such simulants for medico-legal and forensic studies where aspects such as bullet deformation and bullet path reconstruction are important. The degree of deformation did not seem to be influenced by overall cranial bone thickness, nor by the overall thickness of the polyurethane simulant. With human bone, a positive relation is observed between projectile deformation and thickness of the tabula externa.