Nonlinear Dynamics and Kinematic Accuracy Reliability Analysis of Planar Multilink Mechanisms with Multiple Irregular Wear Clearances

In this paper, for the problem of irregular wear clearances in planar multilink mechanism, dynamic model as well as reliability model of kinematic accuracy are proposed. The worn kinematic joint undergoes surface reconstruction, and an analysis is conducted on how varying friction coefficients and initial clearance values influence the mechanism’s dynamic characteristics after wearing. Firstly, utilizing the Lagrange multiplier method, a rigid-body dynamics model for the mechanism that includes multiple revolute joint clearances is developed. Secondly, a wear prediction model for the revolving joint clearance is formulated utilizing the Archard wear model, and a rigid-body dynamics modeling approach is proposed for the multi-link mechanism characterized by multiple revolving joint wear clearances. Subsequently, based on first-order second moments method and the strength-stress interference model, the failure conditions are defined and the kinematic accuracy reliability model of a planar multi-link mechanism containing multiple irregular wear clearances is established. Through an analysis of wear characteristics across varying friction coefficients and initial clearance values, intricate relationship between friction coefficient and wear is elucidated, and impact of initial clearance values on wear characteristics. In addition, the proposed method is verified by ADAMS. Considering the extensive utilization of multi-link mechanisms in real-world applications, the developed methodology exhibits broader generalizability. This study integrates the Archard wear model with the Lagrangian multiplier method to establish a dynamic model accounting for multi-clearance irregular wear. This integration not only enables the prediction of wear effects on mechanism dynamic characteristics but also facilitates the analysis of post-wear dynamic responses and nonlinear behaviors. By further studying the influence of the wear clearance on the nonlinear dynamic characteristics of the mechanism and analyzing the reliability of the motion precision of the mechanism, the theoretical basis and practical guidance for the design and maintenance of the mechanism are provided.