Chaos Identification and Dynamics Analysis of Mechanism Considering the Coupling Effect of Clearance and Elastic Deformation

The factors of disturbance such as clearance and elastic deformation of components are the primary contributors leading to the decline of performance and accuracy of the mechanism. In order to more accurately predict dynamics behavior, this paper takes six-bar mechanism as research object, and puts forward an accurate modeling method of the nonlinear dynamics of multi-link mechanism (MLM) under the coupling action of clearance and elastic deformation of the component. Based on the “contact–separation–collision” model, a revolute clearance model is established. Based on the reference point coordinate method (RPCM) and the absolute node coordinate formulation (ANCF), the rigid-flexible coupling dynamics model of the mechanism is established. Then, a dynamics model of rigid-flexible coupling mechanism with revolute clearance is derived by coupling revolute clearance and the rigid-flexible coupling dynamic model. Influence of the coupling action between revolute clearance and elastic deformation of the member on dynamics response of the MLM is investigated. Furthermore, the chaotic phenomenon is identified qualitatively and quantitatively by phase diagram, Poincare map and largest lyapunov exponent (LLE). The reliability of the mechanism is studied. The validity of the theoretical model is verified through a comparison of virtual simulation results and numerical results. This paper aims to provide a systematic theoretical foundation for the research of nonlinear dynamics of high-precision and high-performance MLM.