EXPERIMENTAL INVESTIGATIONS ON DYNAMIC BACK FACE DEFLECTION CAUSED BY BALLISTIC IMPACT ON COMBAT HELMETS AND THE EFFECT TO THE HUMAN SKULL

Nowadays ballistic protective helmets are made of synthetic composites like para-aramide fibers and advanced laminate materials (UHMWPE). The absorption of impact energy occurs through plastic and elastic deformation. The so-called 'dynamic back face deflections' caused by the kinetic energy of the projectile during the ballistic impact can generate serious, irreversible traumatic head injuries. That leads to the question: Which cranio-cerebral injuries are to be expected due to a bullet impact without penetration and which clinical implications for the wearer of the helmet can arise? This paper presents a first prototype of a head-shaped measurement setup for ballistic impact tests of combat helmets. Shooting tests were conducted and force-time sequences caused by the helmet-head contacts during the impact were obtained. The force values of additional trials are planned to be loaded onto a 3D human head finite element model. The objective of the work is the biomechanical interpretation of the simulations. They shall allow conclusions on possible cranio-cerebral injuries and clinical implications.