DYNAMICS ANALYSIS OF PLANAR MECHANISM WITH REVOLUTE JOINT CLEARANCE BASED ON FINITE PARTICLE METHOD

The presence of the clearance in a planar revolute joint makes the journal of the joint easy to collide with the bearing, so that the dynamic responses of the mechanism with clearance revolute joints are different from an ideal mechanism. Based on the finite particle method (FPM), conducts the dynamics analysis on the planar mechanism with revolute joint clearance. Firstly, the particle motion governing equations and the internal force formula of the planar beam element of the FPM are developed. Then the Lankanani-Nikravesh model and a modified Coulomb friction model are introduced to calculate the contact as well as friction forces during the collision of the bearing and the journal in a clearance joint. The dynamics analysis of a planar four-bar mechanism and a slider-crank mechanism are conducted, and the correctness and effectiveness of the proposed method are validated. The results show that:a clearance joint has little effect on the displacement and velocity of mechanism motion, but the oscillation of acceleration appears due to the clearance. Compared with an ideal joint, the peak value of the contact force in a clearance joint increases dramatically. The dynamic responses of a flexible mechanism due to joint clearance is small compared to the response of a rigid mechanism. The existence of multiple clearance joints increases the dynamic responses of the mechanism than the existence of a single clearance joint.