Research on Dynamics of Planar Multi-body Systems with Clearance Joint Based on an Improved Nonlinear Contact Force Model

Found on the elastic contact force model, an improved nonlinear model for cylindrical rotating joints is proposed, considering the impact of geometric dimensions of the rotating joint on nonlinear stiffness coefficient. The validity of the improved nonlinear model is verified by comparing it with the common L-N model. To research the influence of clearance on the dynamic response of multi-body systems, dynamic model of a planar four-bar mechanism with clearance was established by using the improved nonlinear contact force model and Lagrange equations. The influence of clearance value on the dynamic characteristics of the multi-body mechanical system is studied, and the Poincaré diagram is used to verify that the existence of clearance is an important factor leading to the aperiodic or chaotic dynamics of multi-body systems. Results shows that as the clearance value increase, vibration amplitude, single impact and wear of the multi-body system increase, and the system presents quasi-periodic or chaotic response, indicating that the existence of clearance is one of the factors causing the nonlinear response of systems.