Research On Elasto-plastic Impact Of Clearance Revolute Joints And Dynamic Analysis Of Planar Mechanism

In the actual mechanism,with the demand for relative motion,and the errors of manufacturing and assembly,as well as the influence of wear,the clearance joints in mechanical systems are inevitable.The clearance existing leads to contact,collision and friction between the elements of the moving pair,which adversely affects the performance of the mechanical system.The accuracy of the contact model is the important factor influencing the simulating results of the dynamic responses of the mechanism.The research of accrute contact force of joints is a key problem in the dynamic analysis of multibody systems with clearance.In this paper,a contact model is proposed for planar revolute joints,and applied to analyze the dynamic of planar mechanisms with clearance.The main research content of this paper is as follows:Firstly,a static contact model of the shaft and shaft sleeve in the elastic deformation stage was developed by combining the improved elastic foundation model,FEM and particle swarm optimization.The accuracy and applicability of the new model are verified by comparing with existing models and experimental results.Based on the contact model of the elastic stage,the static contact model of the plastic deformation stage and the unloading stage is established.Secondly,for the deficiency that the static contact force model cannot describe the energy loss during the collision,a damping normal impact model was proposed based on the contact model in loading stage.Compared with the conventional model,the normal impact model proposed in this paper has higher calculation accuracy under different impact stages and restitution coefficient.The new model is introduced into the dynamic analysis of the crank slider mechanism with clearance,and compared with the experimental results,to further verify the effectiveness of the new model.Finally,combining the new model with the improved Coulomb friction model,a dynamics model of 3-PRR mechanism with clearance is proposed.The numerical simulation result is compared with Adams simulation results to verify the effectiveness of the dynamic model.The simulation parameters were changed to study the influence of different impact model,clearance size,movement trajectory and joint materials on the dynamic characteristics of the mechanism.