Research on the Dynamic and Reliability of Planar Multi-Link Mechanisms with Multiple Clearances

This study aims to explore the dynamic behavior of a planar multilink mechanism manifesting multiple clearances under varying operational conditions. It employs the planar six-bar mechanism as the subject of investigation, and deploys the L-N normal collision force model in combination with the modified Coulomb friction force model to construct a nonlinear dynamic model of a planar multilink mechanism with multiple revolute pair clearances. The Lagrange multiplier method is utilized to establish the rigid-body dynamics equations of a mechanism containing multiple revolving clearances. To scrutinize the mechanism's stability, the paper introduces a novel approach to compose a kinematic accuracy reliability model which is based on strength-stress interference theory. The model is solved by numerical calculation. The effects of clearances at different joints and different numbers of clearance-containing kinematic pairs on the dynamic response, nonlinear characteristics, and reliability of kinematic accuracy of planar multi-linkage mechanisms are comparatively analyzed. The findings show that the peak dynamic response of the plane multilink mechanism with multiple clearances increases and the oscillation frequency of the dynamic response curve increases with the increase of the driving speed and the increase of the clearance value. Compared to the mechanism considering a single clearance, when multiple clearances coexist in the mechanism, the nonlinear dynamic behavior on the mechanism is greater and the dynamic reliability accuracy is significantly reduced. This study can provide a theoretical basis for the modeling and analysis of the dynamic output of plane multilink mechanism with multiple clearances under different working conditions, and provide a reference for the quantitative analysis of the reliability of multilink mechanism with multiple clearances.