Dynamic Characteristics Of Mechancal With Three-dimensional Clearance Considering Pressure Distribution In Contact Region

With the continuous improvement of the performance of modern mechanical equipment,its reliability,precision and service life have gradually become the focus of research.As a basic connection mode,rotating pairs are widely used in mechanical structures,but there is an inevitable clearance,which will bring internal collision,vibration and other phenomena affect the dynamic characteristics of mechanical systems seriously.Especially considering the collision between shaft and shaft sleeve in three-dimensional space,the contact state of rotating auxiliary elements is more complicated,and the dynamic characteristics of the system are more difficult to be predicted.Therefore,according to the different contact states,considering the characteristics of the pressure distribution in the contact deformation region along the contact length direction,this thesis studies furtherly the relationship between the contact force and the deformation between the shaft and the sleeve of the three-dimensional clearance rotating pair.The main work is as follows:(1)Based on the Winkler model,considering the contact deformation and pressure distribution along the axis length,the model was extended axially,and an improved Winkler contact force model was established for the three-dimensional clearance rotating pair parallel to the axis of the shaft and the bushing.According to the Winkler elastic foundation model and the Hertz ellipsoidal pressure distribution hypothesis,the contact deformation region was simplified for two different spatial contact states(single point contact and two-point contact)between the shaft and the sleeve when the axis was tilted.The pressure distribution of the whole contact deformation region was calculated,and the contact force model of the three dimensional clearance rotating pair was established considering the pressure distribution characteristics of the contact region when the axis was tilted.(2)ABAQUS finite element software was used to simulate the contact separation process between shaft and sleeve in a three-dimensional clearance rotating pair.The contact characteristic curve of shaft and sleeve was compared with the numerical analysis results of the contact force model established in this thesis.The relationship between the contact force and the deformation is basically consistent,which proves the accuracy of the model established.the influence law of initial collision velocity,clearance size and axis Angle on contact force,deformation and energy loss during collision is further explored by using MATLAB numerical simulation analysis.(3)Based on the contact force model established,the ADAMS dynamic simulation software is developed,and the crank slider mechanism with clearance(two-dimensional and three-dimensional clearance)is taken as the research object by the method of joint subroutine.The dynamics simulation is carried out from multiple angles(crank speed,clearance size,clearance quantity and position).Taking the sliding block velocity,acceleration and contact force change between shaft and shaft sleeve as evaluation indexes,the dynamic characteristics of the mechanism with two dimensional clearance and three dimensional clearance were compared respectively,and the influence of three dimensional clearance on the dynamic characteristics of the mechanism was analyzed qualitatively.