The objective of this work was to validate the non-linear viscoelastic constitutive model of brain tissue that was developed in Hrapko et al. (2006) and has shown to provide a good prediction of the shear response. The model predictions were compared to compression relaxation results up to 20% strain of porcine brain tissue samples. Compression and shear results wereobtained from the same samples to reduce the effect of inter-sample variation. Compression measurement results with and without initial contact of the sample with the loading plate were compared. The influence of a fluid layer surrounding the sample and the effect of friction were examined and were found to play an important role during compression measurements. The model has been implemented in the explicit Finite Element code MADYMO. Model simulations with varying boundary conditions are used to interpret the compression results. Simulations using the non-linear constitutive model and its linearised version in a 3-D head model showed a difference in the maximum stress and strain responses of 20% and 50%, respectively. For the covering abstract see ITRD E141762.
Samenvatting