Effects of the Varying Normal Force on the Stick Slip Motion of Systems with Friction

Abstract

In most cases, the normal force applied to mechanical systems with friction is supposed to be constant for convenience. However, through experiments, normal vibration has been proved to have an effect on the stability of mechanical systems. Aiming at uncover the effects of the varying normal force on the stick slip motion, a belt driven system with LuGre friction is investigated. The driving velocity is considered as the critical parameter for stick slip occurrence. By means of the Jacobian matrix and the Taylor expansion, the critical driving velocity is achieved analytically as a function of frequency and acceleration of the varying normal force. In addition, the influence of the varying normal force on the size of limit cycles is also studied numerically. Results show that the variation of the applied normal force has an obviously effect on the stability of mechanical systems, and it should not be ignored in the structure design and the stability analysis for high precision mechanical systems.