Proposition of High Accuracy Identification Method of Contact Stiffness of Joint

The contact stiffness of joints has been evaluated experimentally and the method quantifying them has been proposed by authors. However it was found out that the range of application for this method was limited, since the method was based on the assumption that the relationship between force and real contact area of the joint is linear. Therefore, in this paper, we consider a widely applicable and more general identification method of the contact stiffness which can be applied to the joints in which the relationship between the force and the real contact area shows non-linear characteristics. As a consequence, following results are obtained. (1) The model of the joint interface with surface roughness can be made as a surface covered by springs with same length and spring constant along the profile of surface roughness. (2)The identification method of the contact stiffness of the joint based on the model can be applied to the joints, even if the relationship between the force and the real contact area of the joints is non-linear. (3) The contact stiffness per real contact area k shows constant regardless of the applied force in the joint where the relationship between the force and the real contact area is non-linear.