Multi-directional optimisation against biomechanical criteria of a head-helmet coupling

The main function of a helmet is to reduce or to avoid injuries that may occur to the head during an impact. Today, helmets are designed to reduce headform deceleration and not optimised to reduce head injury. The aim of this work is to optimise numerically a full face helmet finite element model (FEM) based on the dynamic behaviour of its components against biomechanical criteria. After a validation with a headform FEM as used in the experimental normative tests (ECE-R022/04), the helmet model was coupled with a previously developed FEM of the human head in order to predict intra-cranial field parameters (brain pressure, Von Mises stress and global energy of the cerebrospinal-fluid) sustained during the normative impacts (frontal, lateral rear and top impact). Results show that normative impacts led some lesions; it is the reason we propose a solution to optimise the helmet's mechanical parameters against intra-cerebral stress levels.