Abstract
The density of foam used as energy absorbing liner material in safety helmets was optimised in this paper using Finite Element Modelling (FEM). FEM simulations of impact tests from certification standards were carried out to obtain the best performing configurations of helmet liner. For each test condition, two best liner configurations were identified as minimising peak impact accelerations: one was composed of layers of uniform foam and the other of functionally graded foam (FGF). It was found that the observed decreases in the peak accelerations for the best performing helmets in various test conditions are directly related to the contact area, the distribution of internal stresses, and the dissipated plastic energy density (DPED). Application of the methods described in this study could help increase energy absorption for current and future equestrian helmet designs.