Abstract
In mechanical designs much attention is to be paid to human beings from the standpoint of comfort and safety. In order to predict and to evaluate the effect of vibration to human body, dynamic characteristic models were built. In this study, a dynamic model of upper human body having vibration input from the sitting surface mainly in vertical direction is built. The model has a structure of spinal column with the head and the neck on neck, where the spinal column is the main transfer path of vibration from the sheet. The model is constructed by using the Multi-Body Dynamics approach. The whole spinal column is curved like a S character, and is a complicated structure. Anatomically the spinal column is made by piling up 32-34 vertebrae having intervertebral discs inbetween. The intervertebral disc is relatively soft compared with the vertebra and is deformable to the load of the spinal column. Therefore it is considered that the intervertebral disc can be expressed by using a rotational spring and a rotational damper, and that the vertebrae are connected by revolute joints. In this paper a simplified model of sitting human having ten degrees of freedom is constructed, where all the parameters are determined based on the fitness of two transmissibilities, that is, experimental one and analytically predicted one. The model was linearized in order to reduce the computational load, and to simplify the behavior. Further application of the model such as the load evaluation inside the spinal column is also examined.
