Dynamic Characteristics Analysis Of Mechanical With Clearance Joint Based On Improved Winkler Contact Model

With the development of modern mechanical structure to the direction of high performance,the reliability,precision and service life of mechanical system have gradually become the focus of attention.Hinged pairs are widely used in mechanical structures,but there are inevitably gaps,especially the uneven wear,which leads to the change of clearance,which has an important influence on the reliability,motion precision and service life of the mechanism.In this paper,the effects of joint clearance and wear on the dynamic characteristics of the mechanism are studied.The following major tasks were completed:The main results are as follows:(1)the traditional Winkler contact model is improved,and the dynamic model of mechanism with clearance is constructed based on the contact model.In view of the deficiency of the traditional Winkler contact model without considering the energy loss during the contact collision,the improved Winkler contact model is obtained by introducing the damping coefficient and the relative collision velocity to consider the energy loss in the contact collision process.The simulation results show that the model can better describe the actual contact collision process.Based on the kinematic description of the hinged pair with clearance,the dynamic equation of the multi-body system considering the clearance between hinges is established in order to further analyze the interspace.The dynamic characteristics of the gap mechanism lay the foundation.(2)based on the improved Winkler contact model,a ADAMS contact force subprogram for complex contact conditions is developed,and the dynamic characteristics of the mechanism with clearance are analyzed.In view of the fact that the contact force model provided by ADMAS is only suitable for simple contact cases and cannot be used to calculate contact forces in complex contact cases,a contact force subprogram based on the improved Winkler contact model is developed and embedded in the multi-body system dynamics simulation software ADAMS.Taking the crank-slider mechanism with clearance as an example,the dynamic simulation is carried out.And from multiple angles(clearance size,number of hinged pairs with clearance,friction and crank speed)Theinfluence of the clearance of the hinged pair on the dynamic characteristics of the mechanism is analyzed.(3)the wear prediction of the joints with clearance is realized,and the influence of the change of clearance caused by wear on the dynamic characteristics of the mechanism is analyzed.Based on the improved Winkler contact model and Archard wear model,the wear prediction model of clearance hinge is established,and the wear prediction program is developed.Based on the dynamic simulation,the prediction of the wear law of hinged joints is realized.In order to reconstruct the surface contour after wear,this paper presents a method to realize the surface contour reconstruction indirectly by contact force subroutine in ADAMS.On the basis of the above research work,the contact impact force and sliding block velocity of wear on hinged pair are analyzed.The effect of the degree and acceleration.The results show that the non-regular wear of the hinge pair with the clearance results in the collision of the hinge sub-elements to be more severe,and the motion stability of the mechanism is reduced.