Abstract: To resolve the discontinuous displacement problem in the joint, a new analysis method based on the interface stress element is proposed. Since the interface stress element method uses a piecewise rigid-body displacement field, the displacement along the structural interface is allowed to be discontinuous，which is beneficial to analyze the discontinuous structure without setting any interlayer elements. According to the Hertz theory and the relation between the normal load and the normal deformation of the asperity, the equivalent elasticity modulus in the joint is deduced by the fitting formula of the joint. Under the condition of the stress wave propagation in a discrete element, the relation between the normal stiffness and the tangential stiffness of the joint is obtained. Furthermore, the equivalent Poisson ratio is deduced by the fitting formula of the joint. To verify the effectiveness of the propose analysis method, this method is applied to a mechanical structure including joints. The comparison between the theoretical and experimental results validates the feasibility of the proposed method. The results presented in this work can be considered as a stepping stone to be used toward the further research of the joint problem.

Key words: Discontinuous media mechanics, Hertz theory, Interface stress element, Joint