Nonlinear numerical prediction of human head/helmet crash impact response.

A nonlinear, finite-element, model is used to examine the biodynamic impact response to helmeted and unhelmeted headforms having human response characteristics. The human response headform is modeled as a spherical brain of nearly incompressible material, a covering of linear elastic dura, a linear elastic spherical skull, and a layer of nonlinear scalp material. The helmet system is modeled as a partially spherical, highly nonlinear, helmet liner material and a linear elastic fiberglass helmet outer shell. In the case of unhelmeted head impact, the brain pressure response predictions made with the model achieve good qualitative correlation with experiments on impacted human cadaver heads. The model is then used to investigate the response attenuating characteristics of a range of nonresilient helmet liner materials. The results of the study establish the importance of matching surrogate structural compliance and mechanical impedance to that of the human system being simulated if proper assessment of safety system performance is to be achieved.