Dynamic analysis and wear calculation of space deployable mechanism considering spherical joints with clearance and coating

In the space deployable mechanism considering spherical joints with clearance, the kinematic stability and working life of will be seriously affected. To address this problem, this paper proposes a nonlinear stiffness coefficient expression and an improved viscous damping coefficient expression considering the wear reduction properties of coatings, so as to obtain a conformal contact force model based on the analysis and comparison of the existing common normal contact force models. The new contact force model is qualitatively analyzed from three aspects, namely clearance size, recovery coefficient, and material properties, so as to demonstrate the correctness and applicability of the model. In the prefabricated space deployable mechanism (RSSP) with spherical joint clearance, the acceleration variation of the actuator is analyzed and compared by using the new contact force model, and the wear quantity of the spherical joints with clearance and coating is predicted. The dynamic results show that spherical joints with clearance have a significant effect on the acceleration of the actuator, and the long working time will inevitably lead to increased vibration and reduce the motion accuracy and life of the mechanism. By comparing with the calculation results of wear, it is found that the wear of spherical joint clearance with coating decreases significantly in all vector directions, and the wear area of the Euler Angle increases slightly compared with that without coating because of the increase of contact collision frequency. Therefore, the wear calculation method and coating strategy proposed in our work can provide a theoretical basis for improving the kinematic accuracy and working life of space deployable mechanism system considering spherical joints with clearance.