Dynamic characterization of motorcycle helmets: Modelling and coupling with the human head

Research into the protection of the human head calls for accurate modelling of both the protection system and the head. This study proposes a model incorporating both lumped parameters of the helmet and the head and their coupling during impact. The mechanical characteristics of the shell and of the helmet liner are determined by modal analysis and dynamic compression tests respectively. The coupling of these two components of the helmet is explored using numerical optimization methods based on impact tests which are also used to validate the model. A new dummy head, developed in a previous study and capable of simulating the relative brain-skull displacement was used in the parametric study of the helmet to optimize the density of the polystyrene liner. The ultimate purpose of the study is to devise methods of evaluating the protective aspects of the helmet and then to provide less-expensive methods for optimizing new products on the basis of biomechanical criteria. So far, the study has shown that the optimum density of the liner can be determined not only empirically but also theoretically. It has also shown that optimum helmet parameters depend on the mechanical properties of the dummy head used. (C) 2000 Academic Press.