| The neck is one of the most vulnerable parts during the vehicle collision. The mostly used method is that a neck finite element model developed using finite element method and validated against the experimental data is used to study the injury mechanism. Many neck finite element models developed by researchers at home and abroad have been used to study the injury mechanism, however, the bionic degree of the existed finite element models need to be improved, which can be presented as follows: the geometry model is usually significant reduced to mesh the model; and the number of the validated experiments is not enough which can be demonstrated by the fact that the existed finite element models are only validated against the drop test without neck muscle and against the volunteer sled test with neck muscle, yet rarely against the extension, flexion and rotation test; solid or shell elements used to connect the adjacent vertebras are employed to model the joints, and the function of the joint composed of the articular surface, joint capsule and joint cavity is not presented actually and the bionic degree of the neck finite element model can be improved. Therefore, though the existed finite element models can give a global accurate kinetic pattern of neck, there exist some shortcomings in the predicted local stress/strain of issues and rotation of the head. To solve the problems above, the following studies are carried out in this paper:(1) The development of the high bionic degree human neck finite element model. The 3D geometrical model of the vertebra is obtained based on the CT data of a 50 th Chinese human male, and the hexahedron mesh is generated. Then the joints and ligaments etc. are modeled based on the anatomy structure, and the material properties of different issues are applied using the published material properties at home and abroad. Finally the human neck finite element model is obtained, which consists of seven cervical vertebra(C1-C7), the first thoracic vertebra(T1), ligament, disc, cervical facet joint, the muscle, and atlantoaxial joint and atlanto occipital joint used for modeling the function of extension, flexion, and rotation of the head. The developed neck model in this research is connected with the previous head model, then a high bionic degree head-neck finite element model is obtained.(2) The finite element model is validated against the experiments in the published references. The flexion/tension/axial rotation/lateral bending experiments conducted by Panjabi et al. is simulated which aims to investigate the effects of ligaments, disc and joints on the angular range of the vertebra; the axial tensile test conducted by Van et al. is simulated which aims to investigate the effects of the constraint conditions and the tensile load eccentricity on the responses of the neck; the head-neck drop test conducted by Nightingale et al. is simulated which aims to investigate the agreements between the experiments and simulations; the low speed rear impact sled test conducted by Davidson et al. is simulated which considers the effect of muscles and aims to investigate the agreements of global movement pattern between the neck and human body.(3) The biomechanical response study of the neck and head in low speed rear impact test. Taking the low speed rear impact test as an example, the simulation is carried out using the validated head-neck finite element model in this study, the responses of the upper cervical spine ligaments, joint capsule ligaments, discs, and the neck injury are presented. The neck injury mechanism is analyzed through the analysis of the responses of the neck, and the neck injury is predicted and analyzed.The developed neck model in this study shows a higher bionic than the previous models and can be applied to study the injury mechanism in car collision, and can provide some guidelines for passengers injury evaluation in car collisions. |
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