Validation of a numerical model for helmet testing with a clay head form

In the past few years, military helmets have greatly reduced the risk of penetrating injuries and saved the lives of many soldiers. However, the risk of a non-penetrating impact has increased and can lead to serious injuries. Behind-helmet blunt trauma (BHBT) is an injury to the human body that results from the back face deformation (BFD) of the head protection armour system, typically a military helmet. In the current study, a finite element model is developed to simulate a clay head form and is validated against experimental data. The clay head form is an aluminium head form based on the penetration head form specified in NIJ0106.01. The empty spaces in the head form are filled with modelling clay and in these parts of the head form it is possible to measure the indentation created by the back face deformation of the tested ballistic protection upon impact. The goal of this work is to develop a stable and flexible numerical model, using the LS-Dyna finite element modelling package, for the helmet support system, which should be able to represent the real model. Finite element validation was done using experimental data of the back face signature of a composite armour helmet system impacted by a 7.62 x 39 M43 round and placed in front of a clay head form.