Human head tolerance limits to specific injury mechanisms

This study presents an original numerical human head model followed by there modal and temporal validation against human head vibration analysis in vivo and cadaver impact tests. The human head FE model developed by ULP presents two particularities : one at the brain-skull interface level were fluid-structure interaction is taken into account, the other at the skull modelling level by integrating the bone fracture simulation. Validation shows that the model correlated well with a number of experimental cadaver tests and predicted intra-cranial pressure accurately. However, for long duration impacts the model reaches its limits. The skull stiffness and fracture force were accurately predicted when compared with experimental values from the literature. This improved numerical human head surrogates has then be used for numerical real world accident reconstruction. Helmet damage from thirteen motorcycle accidents was replicated in drop tests in order to define the head's loading conditions. A total of twenty two well documented American football head trauma have been reconstructed as well as twenty eight pedestrian head impacts. By correlating head injury type and location with intra-cerebral mechanical field parameters, it was possible to derive new injury risk curves relative to specific injury mechanisms.