Analysis On The Impact Of Dry Friction On The Features Of The Mechanical Vibration

The friction widely exists in the mechanical movements, which not only affects the lifetime,accuracy and work efficiency of the mechanisms, but also has some big effects on the dynamic features of the mechanisms. When the mechanical systems are vibrating, friction is always thought to be a kind of damping that can absorb the energy and reduce the vibrations. However, studying the the usual mechanical vibrations, we always ignore the functions of frictions, so that the studying results could not reflect the real truths. In fact, the frictions has a clear characteristic of nonlinear specialty, that is if the static friction turn to the dynamic friction or the direction of the mechanical movements changes, the direction of the frictional force would change at the same time, which make the dynamic behaviors of the systems difficult to predict. In this paper, considering the nonlinear characteristic of the friction, we studied its impact on the features of the mechanical vibration, and this will instruct the practical engineering work in theory.The content of this paper includes the following statements:1. In the paper, the author summarized the researching significance of dry friction, and introduced the developing process of frictional theory, including several significant frictional models for the research on frictional theory. Beside, the author also introduced the current situation and the achievements of the research on dry friction systems through reading a amount of papers written by others.2. After introducing the concept of self-vibration, the author elaborated the occurring process of self-vibration by the ways of both the linear analysis and energetic analysis.3. The author learned the dynamic features of self-vibration affected by Coulomb's friction in the ways of both theoretic analyzing and digital computating and did the nonlinear analysis by the method of average with getting the analytic solution to the response of the vibration system. Finally, the author compared the two results of the digital computating and the analytic solution.4. Finishing the digital computation by using MATLAB, the author got the response curve of the vibration system that included Coulomb's friction and was affected by harmonic vibration force, and analyzed the specialties of the amplitude-frequency of the response. Through analyzing the linear-equivalent force and the nonlinear-dynamic force of the vibration system that included Coulomb's friction and was affected by harmonic vibration force, the author finally found the approximate analytic solution to the response of the vibration system.