Research Of Collision Model Of Rotating Pair With Clearance

With the demand of the precise analysis of dynamic characteristics of the mechanism with clearance is higher and higher,many scholars in the world have focus on setting up an accurate contact collision force model.One of the development direction of dynamic analysis of mechanism with clearance is setting up a contact collision force model considering contact surface topography.Aimed at this direction,a series of studies about the contact impact force model is studied in this paper.At first,based on the fractal theory,the contact deformation process of contact surface microconvex body is analyzed,and a modified stiffness coefficient model is established,which considered the surface roughness of contact surface.On this basis,a modified nonlinear spring damping model was established based on the expression of the contact impact force in Lankarani-Nikravesh model.Then,based on the modified contact force model,analysis the influence law of surface roughness,initial velocity and clearance size on the impact force.The contact force analysis was used to analyze the collision process under different recovery coefficients,initial velocity and roughness,and then compared with other contact force models.It shows that the modified model can describe the impact process with different restitution coefficients,which is suitable for large clearance and small clearance.Especially,the modified model is more accurate in calculating small clearance contact collision.In addition,a collision experiment platform is designed and set up,through comparing the maximum contact collision force under different initial velocity of experimental measurements and theoretical calculation value and experimental results shows the accuracy of the modified contact collision force model.Finally,based on the modified contact impact force model,the dynamic model of single gap manipulator is established by means of single gap manipulator.Analysis with single gap mechanical arm manipulator joints when driving force known motion trajectory of the contact force and the center of the shaft pin,rotates at a constant speed as well as the mechanical arm under different rotation speed and clearance,contact stiffness shaft pin contact force and the center of the trajectory.