title: Finite element study of human pelvis model in side impact for Chinese adult occupants.
abstract: OBJECTIVE
  The occupant's pelvis is very vulnerable to side collision in road accidents. Finite element (FE) studies on pelvic injury help to design occupant protection devices to improve vehicle safety. This study was aimed to develop a highly biofidelic pelvis model of Chinese adults and assess its sensitivity to variations in pelvis cortical bone thickness, bone material properties, and loading conditions.
  
  
  METHODS
  In this study, 4 different FE models of the pelvis were developed from the computed tomography (CT) data of a volunteer representing the 50th percentile Chinese male. Two of them were meshed using entirely hexahedral elements with variable and constant cortical thickness distribution (the V-Hex and C-Hex models), and the others were modeled with hexahedral elements for cancellous bone and variable or constant thickness shell elements for cortical bone (the V-HS and C-HS models). In model developments, the semi-automatic multiblock meshing approach was employed to maintain the pelvis geometric curvature and generate a high-quality hexahedral mesh. Then, several simulations with postmortem human subjects (PMHS) tests were performed to obtain the most accurate model in predicting pelvic injury. Based on the most accurate model, sensitivity studies were conducted to analyze the effects of the cortex thickness, Young's modulus of the cortical and cancellous bone, impactor velocity, and impactor with or without padding on the biomechanical responses and injuries of pelvis.
  
  
  RESULTS
  The results indicate that the models with variable cortical bone thickness can give more accurate predictions than those with constant cortical thickness. Both the V-Hex and V-HS models are favorable for simulating pelvic response and injury, but the simulation results of the V-Hex model agree with the tests better. The sensitivity study shows that pelvic response is more sensitive to alterations in the Young's modulus of cortical bone than cancellous bone. Compared to failure displacement, peak force is more sensitive to the cortical bone thickness. However, displacement is more sensitive to the Young's modulus of cancellous bone than peak force. The padding attached on the impactor plays a significant role in absorbing the impact energy and alleviating pelvic injury.
  
  
  CONCLUSIONS
  The all-hex meshing method with variable cortical bone thickness has the highest accuracy but is time-consuming. The cortical bone plays a determining role in resisting pelvic fracture. Peak impact force appears to be a reasonable injury predictor for pelvic injury assessment. Some appropriate energy absorbers installed in the car door can significantly reduce pelvic injury and will be beneficial for occupant protection.
authors.affiliation: a School of Mechanical and Automotive Engineering , South China University of Technology , Guangzhou , Guangdong , China.
authors.forename: Zhengwei
authors.initials: Z
authors.lastname: Ma
authors.forename: Fengchong
authors.initials: F
authors.lastname: Lan
authors.forename: Jiqing
authors.initials: J
authors.lastname: Chen
authors.forename: Weiguo
authors.initials: W
authors.lastname: Liu
mesh_terms: D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D000328:Adult; D002681:China; D020342:Finite Element Analysis; D006801:Humans; D008297:Male; D008954:Models, Biological; D010384:Pelvic Bones / Q000000981:diagnostic imaging / Q000293:injuries*; D014057:Tomography, X-Ray Computed
keywords: biofidelic; finite element; pelvis model; sensitivity study; side impact