The discretization method and multi-contact force model on 3D cylindrical clearance joint for multibody dynamics of spatial mechanical system

A discretization principle of multi-slice method and multi-contact model is proposed to investigate the line contact behavior of 3D cylindrical clearance joints in spatial mechanical systems. The cylindrical contact surface of the journal is discretized into multiple slices firstly. Then, we derive the contact force/indentation relationship and the hysteresis damping formula between the multi-slice and the bearing based on Lankarani and Nikravesh's model, and establish the contact force model between the multi-slice and the bearing. Finally, the nonideal line contact of 3D cylindrical clearance joint is well simulated by adding more contact points, and the displacement, tilt angle and distributed contact force of local or whole line contact between the journal and the bearing are obtained accurately by using the proposed method. Furthermore, the contact stiffness and the overall stiffness of 3D cylindrical joint are well approximated by the distributed contact forces. We found that loads applied at both ends of the journal affect the distributed contact forces of all the slices mutually, and the contact type of 3D cylindrical clearance joint alternates between local and whole line contact. By applying the proposed method, the dynamic responses of spatial mechanical systems with 3D cylindrical clearance joint are simulated more accurately in the case of time-varying driving motion and unbalanced complex loads.