Finite element modeling of aortic tissue using high speed experimental data

Traumatic rupture of the aorta (TRA) is responsible for 10% to 20% of motor vehicle fatalities (Viano 1983). Both finite element (FE) modeling and experimental investigations have enhanced our understanding of the injury mechanisms associated with TRA. Because accurate material properties are essential for any FE model predictions to become trustworthy, the objective of the current study was to identify a suitable material model and model parameters for aorta tissue that can be incorporated into FE aorta models for studying TRA. An Ogden rubber material (Type 77B in LS-DYNA version 970) was used to simulate a series of high speed uniaxial experiments reported by Mohan (1976) using a dumbbell shaped FE model representing human aortic tissue. Material constants were obtained by fitting model simulation result against experimentally obtained corridors.; The sensitivity of the Ogden rubber material constants G and alpha (alpha) on the results of model behavior was also examined. One single set of material constants (alpha = 25.3, G = 0.02 GPa, and mu = 0.6000E-06 GPa) was found to fit uniaxial data at strain rates of approximately 100 s-1 for both younger and older aortic tissue specimens. Until a better material model is derived and other experimental data are obtained, it is recommended that the Ogden material model and associated constants derived from the current study be used to represent aorta tissue properties when using FE methods to investigate mechanisms of TRA.