Research On Dynamic Characterisitcs And Wear Of Mechanism With Joint Clearance

With the development of precision mechanical engineering,the movement accuracy,reliability and service life of the mechanism have been put forward for higher requirements,and the existence of clearance in revolute joints has a larger impact on dynamic characteristics,positioning accuracy,stabilization of mechanical system.In addition,the mechanism after long time operation,the wear of revolute clearance joints can also cause problems such as lower performance and the decrease of the precision of mechanism.In this work,the dynamics characteristics and wear phenomenon of the revolute clearance joints in mechanical system is researched.The contents are as follows:Considering the wear theory of kinematic pair mainly adhesion wear,a wear model which is suitable for mechanical system with revolute clearance joints is established based on Archard wear model.Due to the fact that the Archard wear model has some limitations in practical application,a nonlinear relationship wear model among wear rate,contact pressure,sliding velocity and material hardness is established based on artificial neural network method,the test results have indicated that the model has a higher prediction precision.At the same time,the dynamic characteristics of slider-crank mechanism with clearance joint is analyzed using numerical simulation methods.Then,the trained BP neural network model is employed to predict the wear of clearance joint,it can be found that the wear depth occurred in the joint surface is non-uniform.In this paper,the adhesive wear model is introduced into the mechanism system based on artificial neural network,and a new methodology for evaluating wear in mechanical systems has been presented.Considering the collision and impact in clearance joints of mechanical system,the finite element model of friction pair of bushing and pin has been established based on ANSYS/LS-DYNA finite element software.Through contact dynamics analysis,it can be obtained that the contact pressure around the joint surface and the most serious wear area in friction surface.In the process,the crank connecting rod mechanism in single cylinder diesel engine is utilized to establish the dynamic analysis model with multi-clearance based on the mechanical system dynamics analytical software ADAMS.The finite element model of linkage has been established through ANSYS,and the flexible linkage is exported into ADAMS to set up a rigid-flexible coupling model of crank connecting rod mechanism with multi-clearance.The dynamic effect of flexible members and clearance joints on mechanical systems is studied in detail.Then,the simulation results show that the dynamic behavior of the slider-crank mechanism with clearances and flexible linkage is very close to the ideal mechanism.Considering the flexible of components and joint clearance,the simulation results is more in line with the actual situation of mechanism,which provides a more reliable basis for mechanism design and optimization.