Characteristic And Experimental Research Of Particle Damper For Shaft Workpiece

Particle damping technology is a new-born vibration passive control technology which was developed in1990’s. It mainly makes use of the pre-existing or attached cavaties of the vibrating structure which are filled with granular material. When the structure is vibrating, collision and friction happen among inter-particle and particle-enclosure wall, converting mechanical energy into heat to dissipate energy, producing damping effect at the same time. Meanwhile, momentum interchange between particles and structure can also suppresee vibration. Particle damping technololy has a lot of advantages, such as:simple in the stucture of the damper, cheap and effective, and can be performed in harsh environment like high temperature, erosion, etc. In this thesis, effect and influencing factors of particle damping are studyed by means of experimentation. And it also attempts to appy this technoloy into shaft workpiece. The main works are:(1) Introducing the source of vibration when the machine tools work. Through the analysis of vibration theory, concluding that the most fragile component to anti-vibration is main spindle—workpiece—tailstock system, and evaluating the feasibility of applying particle damping technology to this system.(2) On the basis of previous research, elastoplastic normal impact dissipation model of two particles is established, which divides a single impact period into three stages:elastic compression stage, elastoplastic compression stage, and elastic restitution stage. The motion differential equations of each stages and expression of coefficient of energy dissipation are given as well.(3) Mechanics of granular media model for particle damping is established in this thesis, which simplifies the acting forces between two particles as spring—damper system, and gives the general process and equations for particle damping.(4) Designing two kinds of externally-mounted particle dampers which are different in the arranging pattern of cavities, summarizing the general principle of particle damper design. In order to estimate the natural frequency and mode shape of the dampers, executing modal analysis for the two dampers by means of FEM, which serves as a reference of experiment. (5) Designing a perfect experimental pattern for the particle damper for shaft workpiece, in order to verify the dissipating effect and influencing factors of particle damper. The experiment proves that:Particle damping is very effective in decreasing vibration of shaft workpieces. It can increase the damping ratio, decrease amplitude of each step, and dissipates the vibrating energy. However, since particle damping is a form of highly nonlinear mechanical behavior, the dampers should be designed in consideration of every possible influencing factor.