Parametric Modeling And Injury Analysis Of Occupant Thorax Under Impact Conditions Concerning Variations Among Populations

In motor vehicle crashes,thoracic injuries are one of the leading causes of disabilities and fatalities.Crash injury data analysis has shown that occupant characteristics,including age,sex,statue and body mass index(BMI),have significant effects on thoracic injuries.Additionally,differences of occupant characteristics between the U.S.and Chinese populations exist.However,current injury assessment tools,such as finite element(FE)human models,generally do not account for different human characteristic and thoracic biomechanical variations among the U.S.and Chinese populations.The objective of this study was to develop the U.S.and Chinese parametric thorax FE models accounting for geometrical and cortical bone thickness distribution variations among the populations,which can be used to analyze the thoracic biomechanical variations under impact conditions among the U.S.and Chinese populations.A new method for calculating the cortical bone thickness in human ribs based on clinical CT scans was developed.By comparing to a series of post-mortem human subjects(PMHS),the errors between the measured cortical bone thickness and calculated one were analyzed to evaluate the accuracy of this method.Based on the U.S.and Chinese clinical CT scans,statistical models of the ribcage geometry and cortical bone thickness distribution were developed as functions of occupant characteristics(age,sex,statue and BMI).The geometrical and cortical bone thickness distribution variations among the U.S.and Chinese populations were analyzed.The effects of human characteristics on ribcage geometry and cortical bone thickness distribution were also investigated.In this study,the U.S.and Chinese parametric thorax FE models were developed,which are able to capture the variability in geometry and cortical bone thickness distribution among the U.S.and Chinese populations.Based on the whole rib PMHS tests and pendulum impact PMHS tests,the validation of parametric rib FE models and human models predicted by subject-specific occupant characteristics were conducted.The results showed that the parametric FE model developed in the study tended to perform more accurately than the baseline FE model.Finally,12 FE human models were developed by morphing the GHBMC 50 th percentile male model to represent the U.S.and Chinese occupants with a wide range of occupant characteristics.A series of pendulum impact simulations were conducted using the 12 morphed GHBMC models to investigate the effects from nation,age and body shape on thoracic response,effective thoracic stiffness and maximum chest deflection.The development of the U.S.and Chinese parametric thorax FE models with realistic rib cortical bone thickness will enable population-based simulations for future vehicle design optimizations and have increased value when used to simulate vulnerable populations which generally were not considered in the current safety design process.