Dynamic Analysis and Stress in Human Body due to Motion

研究了人体在跳跃到坚硬表面时的减震机理，以减小垂直加速度。建立了带有连杆关节的人体下肢动力学模型。该模型由收缩单元、串联弹性单元和粘性单元组成，并进行了实验和理论研究。结果表明，深度弯曲可以被动吸收冲击，膝盖弯曲运动可以更主动地吸收冲击。以人体与工具的耦合运动为例，从理论上研究了击打网球在手腕和肘部所产生的力和力矩。建立了球、球拍和手臂的动力学模型，计算了振动模态和冲击响应。可以通过设计球拍使击球点成为节点或球和球拍的固有频率重合来减小力。同时对天然牙和种植体进行了动力学分析，并对牙和骨周围的应力分布进行了研究，以期找到最佳的治疗方案。

The shock absorbing mechanism of human body to minimize the vertical acceleration during jumping down to a hard surface was investigated. The dynamic model of human lower limb was built with a link joint. The muscle model was consisted of a contractile element, a series elastic element and a viscous element, and the experimental and theoretical investigations were carried out. The results showed that the shock could be absorbed passively by deep bending, and it could be absorbed more actively by bending motion of knees.As an example of coupled motion of a human body and a tool, the forces and moment in the wrist and the elbow caused by striking tennis ball were theoretically investigated. The dynamic model of a ball, a racket and an arm were formulated, and the modes of vibration and impulse response were calculated. The forces can be decreased by designing the racket such that the striking point becomes the nodal point or the natural frequency of the ball and racket coincides each other.The dynamic analysis of the natural teeth and endosseous implant were also carried out, and stress distribution around teeth and bone were investigated in order to find the optimum medical treatment.