Study On Dynamic Modeling Method Of Non-ideal Articulated Mechanism

With the progress of technology,traditional study of mechanism dynamics is no longer limited to the analysis of ideal articulated mechanisms.The nonlinear mechanical response caused by some non-ideal factors has attracted more and more attention.It is important to predict the movement of non-ideal articulated mechanisms,especially in the fields of automobiles,ships and aerospace,which need to accurately control the dynamic response of mechanical systems.In this paper,the clearance,one of the typical non-ideal factors,is taken as the starting point,and a series of theoretical and experimental studies on dynamic modeling methods of non-ideal articulated mechanisms with three-dimensional clearance are carried out,which provides a feasible idea for accurate prediction of mechanism dynamic response.The main contents in this paper are as follows:Firstly,four nonlinear normal contact force models are summarized systematically,including the modeling principle and approximation method of the model.Taking the single centripetal collision process of two balls as an example,the characteristics of these contact force models are compared and analyzed.At the same time,a small ball free fall collision experimental system is designed,and the collision force model verification experiments under different parameters are carried out.Moreover,the comparison between experiment and simulation provides a basis for the subsequent dynamic modeling of three-dimensional clearance rotating joint.Secondly,aiming at the contact collision problem of three-dimensional clearance rotating joint,the contact collision force model is deduced.Based on the position and direction relationship between the pin shaft and the bearing,the radial and axial deformation are obtained.Combined with the elastic collision approximate model and Flores collision force model,the radial collision model and axial collision model of the three-dimensional clearance rotating joint are established respectively,which lays a foundation for the subsequent multi-body system dynamics modeling of the clearance mechanism.The contact collision force model is verified and analyzed by a set of cylinder-semicircular-ground collision models.Thirdly,the dynamic modeling method of the mechanism with clearance is proposed.Taking the parallel double crank slider mechanism with clearance as an example,based on the Lagrange equation and combined with the contact force model of three-dimensional clearance rotating joint,the dynamic model of the mechanism is established,so as to study the influence of clearance size,crank speed and other parameters on the mechanism with three-dimensional clearance rotating joint.Fourthly,an experimental system of crank slider mechanism is designed and built,and experimental studies of different radial clearance and crank speed are carried out,which verify the accuracy of contact force model and the feasibility of the dynamic modeling method proposed in this paper.