Development of a New Method for the Engineering Pre-design of Sport Helmets

Aim of this work is the development and preliminary validation of a method enabling to estimate the theoretical minimum value of the thickness of helmet padding, given the padding preliminary geometry, the energy absorption requirements and the mechanical properties of the material chosen for the development. The approach is based on the close relationship between the absorbed energy and the crushed foam volume of an helmet padding, given the padding curvature and the shape of the contact area at the helmet-anvil interface. Starting from a geometric input such as the head curvature at a certain position, on the basis of the stress-strain curve of a chosen foam, the crushed volume is incrementally increased until the corresponding absorbed energy equals the amount of impact energy transferred to the helmet. The application to a known set of data gave a good correspondence between calculated and measure results, hence encouraging towards a wider validation and its application for obtaining the thickness distribution of a new prototype.