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The validated finite element head model(FEHM)of a 3-year-old child,a 6-year-old child and a 50 th percentile adult were used to investigate the effects of head dimension and material parameters of brain tissues on the head rotational responses based on experimental design.Results showed that the effects of head dimension and directions of rotation on the head rotational responses were not significant under the same rotational loading condition,and the same results appeared in the viscoelastic material parameters of brain tissues.However,the head rotational responses were most sensitive to the shear modulus(G)of brain tissues relative to decay constant(β)and bulk modulus(K).Therefore,the selection of material parameters of brain tissues is most important to the accuracy of simulation results,especially in the study of brain injury criterion under the rotational loading conditions.

A validated 5th and 95th percentile Chinese head model was used to investigate the influence of head dimensions on the biomechanical responses by comparing acceleration, intracranial pressure and shear stress of the heads with different dimensions under the same impact energy. Moreover, the reasonability of scaling method used in the research considering head dimensions was discussed by respectively scaling the small head to a big one and scaling the big head to a small one. It therefore more scientifically provides a newer and more scientific reference for the assessment of head injury.

Based on the biomechanical response of human knee joint to a front impact in occupants accidents, a finite element (FE) model of human knee joint was developed by using computer simulation technique for impacting. The model consists of human anatomical structure, including femoral condyle, tibia condyle, fibular small head, patellar, cartilage, meniscus and primary ligament. By comparing the results of the FE model with experiments of the knee joint in axial load conditions, the validation of the model was verified. Furthermore, this study provides data for the mechanical of human knee joint injury, and is helpful for the design and optimization of the vehicle protective devices.