Strain-Rate Dependent Biomechanical Response of the Liver in Far-Side Vehicle Impacts

To improve occupant liver injury prediction in vehicular far-side collisions, this study established a finite element far-side impact platform incorporating a simplified sled buck, a restraint system, and loading curves. Impact direction and velocity were varied to examine their effects on hepatic pressure loading. Because previous liver material inputs are primarily derived from porcine data and may not represent the rate-sensitive and nonlinear response of human liver tissue, human-derived liver material data from multi-strain-rate tensile and compression tests were introduced. Four hepatic parenchyma curves were evaluated through organ-level impact and compression validation, and one validation-supported representative curve was selected for the current THUMS single-curve implementation. The simulations showed that loading direction and material selection affected the predicted liver pressure response. Peak liver pressure was higher under oblique impact than under pure side impact. When the validation-selected 0.1 s -1 parenchyma curve was applied, predicted liver pressure loading increased, and the pressure-based injury trend was more consistent with reported far-side injury mechanisms. These findings indicate that impact velocity, loading direction, and human liver material input influence far-side hepatic pressure loading and provide a biomechanical reference for occupant restraint-system optimization.