A quantitative analysis method for contact force of mechanism with a clearance joint based on entropy weight and its application in a six-bar mechanism

Contact force in a clearance joint affects the dynamic characteristics and leads to nonlinear response of the mechanism.It is necessary to assess the nonlinearity of contact force quantitatively.Therefore,a new method named contact-force entropy weight is proposed in this paper.This method presents a comprehensive description of the judgment matrix in the X,Y,and Z directions.To assess the influence degrees of different clearances and angular velocities on the contact force,the method is applied to numerical calculation and simulation of a six-bar mechanism with a clearance joint to illustrate its application and investigate the influence degree of angular velocity and clearance on the contact force.By combining the simulation results and theoretical calculations,the influence degrees of different clearances and angular velocities on the contact-force entropy weight of the six-bar mechanism with a clearance joint are revealed.It is found that the angular velocity has a significant influence on the contact force entropy weight of the clearance joint,showing that the contact-force entropy weight is a feasible new method of assessing non-linearity of contact force quantitatively.The method gives a theoretical reference for quantitatively analyzing the nonlinear dynamics.