Comparison of Whole Body Kinematics between Fracture and Non-Fracture Finite Element Human Body Models during Side Impact

The age-specific finite element human body models representing rib fracture were developed by the authors. They are limited, however, in quantitative evaluation of a strain that exceeds the predetermined threshold, i.e. the strain measured on the “fracture” model is censored. A “non-fracture” model can evaluate the value of the strain throughout the impact, but may be at a disadvantage when trying to represent post-fracture kinematics. The objective of the present study is to examine the compatibility between “fracture” and “non-fracture” finite element (FE) human body models in order to establish the method to quantify the probability of the rib fracture. The authors conducted a series of simulated side-impact tests using human body models with and without representation of the rib fracture. Simulations were done in compliance with the IIHS SICE protocol. The results indicate that the whole-body kinematics of the “non-fracture” human models was almost identical to those of “fracture” models. The locations in the “non-fracture” models, where the values of the strain reached the pre-determined threshold, were well correlated with those where the element elimination was activated in the “fracture” models. The results suggested the feasibility of the methods for probability-based evaluation of the rib fracture using human FE models.