Influence of headform mass and inertia on the response to oblique impacts

Current standard headforms used for sport and automotive helmet certification have poor biofidelity in terms of their mass and moments of inertia (MOI) and may not be suitable for evaluating helmet performance in oblique impacts. In this study, a novel inertially correct headform is designed and built and is compared with the HIII 50th percentile male and two standard (EN960:2006) headforms. Oblique impact response of both un-helmeted and helmeted headforms is investigated. This study shows that current standard headforms are unsuitable for oblique impact tests. For example, it has been shown that for helmeted impacts, differences in headform inertia of 98, 81 and 15% result in differences of 71, 68 and 29% in the peak rotational acceleration impact response about the x-, y- and z-axes rotation, respectively. Future certification tests that include oblique impacts will have to use more biofidelic headforms based on an appropriate population.