Effect of human head morphological variability on the mechanical response of blast overpressure loading

A methodology is introduced to investigate the effect of intersubject head morphological variability on the mechanical response of the brain when subjected to blast overpressure loading. Nonrigid image registration techniques are leveraged to warp a manually segmented template model to an arbitrary number of subjects following a procedure to coarsely segment the subjects in batch. Finite element meshes are autogenerated, and blast analysis is conducted. The template model is initially constructed to enable the full automated implementation and application of the proposed methodology. The application of the proposed approach for an anterior-oriented blast has been demonstrated, and the results reveal that the pressure response in the brain does exhibit some dependence on head morphological variability. While the magnitude of the peak pressure response can vary by more than 30%, its location within the brain is unaffected by head morphological variability. A linear least squares analysis was conducted to demonstrate that the peak magnitude of pressure is uncorrelated with head volume while it is correlated with aspect ratio relating to the amount of exposed surface area to the blast. These features of the pressure response are likely due to the peak pressure occurring during the early stages of stress wave transmission and reflection. As a result, the pressure response due to blast overpressure loading is predominantly loading dependent while morphological variability has a secondary effect.