Rheology of brain tissue: Experiments, simulations of temporary cavitation and applications in forensics*

Experimental data on uniaxial compression and relaxation of brain tissue are discussed and compared to the predictions from a recently developed novel rheological model. Here, the uniformly valid rheological parameters of the model are determined using the experimental data. They remain valid in different rheometric experiments without any further variation, as the comparison with the experimental data for swine brain tissue reveals. These are the following four parameters: G (the shear modulus), κ (the bulk modulus), α (the dimensionless degree of hyperelasticity), and θ (the viscoelastic relaxation time). Furthermore, the current rheological model with the established values of the parameters is used in a dynamic model of bullet penetration into brain tissue after a short-range shooting, when muzzle gases and/or air enter the bullet channel, causing its widening/shrinkage (the temporary cavitation), wave propagation, fragmentation and backspatter of brain tissue [1]. This is an important issue in forensic science since there is an urgent demand for physics-informed models to recreate and analyze crime scenes.