RESUMO
Objective To construct and validate a 3D finite element model of pelvis-femur-soft tissue complex including artery, and investigate the mechanical response of pelvis artery under side impact loads. Methods The 3D finite element model of the pelvis-femur-soft tissue complex was constructed from CT images of one female volunteer, including bone tissues, arteries, enveloping soft tissues, cartilage and ligaments of the pelvic joints (sacroiliac joint, hip joint and pubic symphysis). The whole model utilized linear elastic solid elements to simulate bone tissues. Nonlinear elastic connector elements were employed to represent ligaments. Soft tissues, including the cartilage, enveloping soft tissues and arteries, were modeled as solid elements with hyper-elastic material. Side impact was conducted on the complex with impact mass of 22.1 kg at the impact velocity of 3.13 and 5 m/s, respectively, and the output of the complex model was then recorded. Results Simulation results matched the results of pelvic side impact experiments reported in literature. When the complex model was impacted at the velocity of 3.31 and 5 m/s, respectively, the maximum equivalent stress of arteries was 98 and 216 kPa, and the maximum principle strain was 14.9% and 20%, respectively. The risk of artery injury was relatively low. Conclusions This established pelvis-femur-artery complex model was validated and thus reliable to be used for investigating the dynamical response and injury analysis on pelvis artery under impact loads, and provides some biomechanical foundation for predicting artery injuries.
RESUMO
Objective To investigate the effect of hip protector on biomechanical response of the human pelvis-femur complex under lateral pelvic impacts during sideways falls using three dimensional (3D) finite element (FE) method. Methods Based on the model database of China Mechanical Virtual Human, a 3D FE model of the pelvis-femur-soft tissue complex including cortical bone, cancellous bone and soft tissue capsule and the pelvis-femur-soft tissue complex with a two layer hip protector were created, respectively. The rigid plane model was also constructed in the two models for ground simulation and constrained in all freedoms. The average hip lateral impact velocity of 2 m/s was applied to the two models, and the time for simulation analysis was set at 20 ms. The stress and strain distribution on the two models under lateral impacts could be obtained by the 3D FE calculation. The comparative analysis was performed to study the effect of the hip protector on biomechanical response of the pelvis-femur complex. Results The hip protector made the peak Von Mises stress appeared 4 ms more earlier in the pelvis-femur complex with a significant decrease in the stress and strain level. The average Von Mises stress peak was decreased by 67.88% and 69.34% in the cortical bone and in the cancellous bone, respectively, and the compressive principal strain peak was decreased by 63%. Conclusions Under lateral pelvic impacts, the two-layer hip protector could act as safeguard for pelvis-femur complex, thus effectively prevent the occurrence or reduce the risk of bone fracture.