Experimental Investigation On The Contact Characteristics Of Rough Surface

Structure accuracy and performance of precision instruments and precision machinery is related to the manufacturing deviation of parts, as well as the contact property between the parts. Contact surface between parts is called" joint surface ". For static and dynamic accuracy analysis of structure, rough surface contact property is refers to mechanics properties of joint surfaces (without considering the properties of electricity, heat, magnetic). In order to improve assembling precision and dynamic performance of precision instruments and machinery, research on the contact coupling characteristics of rough surface is particularly important. The main work is as follows:(1) The theoretical basis of the laser ultrasonic technique, surface acoustic wave propagation theory and rough surface contact theory are researched. It is theoretically proved that the research on contact stress of rough surface adopting of laser ultrasound is feasible.(2) Laser ultrasonic experiment system is built to research the relationship between contact area surface-pressure (the force per unit area), surface roughness and acoustic surface wave (ASW). The experiment confirmed the feasibility of using laser generated acoustic surface wave technology to detect the rough surface contact mechanics properties. SAW attenuation effect of the surface pressure, between the joint surface, was founded. Single valley curves relationship between the amplitude attenuation in the propagation process and surface pressure is measured. In the end, the quantitative relationship between joint surface roughness and signal attenuation amplitude in the propagation process is obtained.(3) This paper put forward a statistical modeling thought for stiffness and damping of joint surface considering the real contact area. Using this idea, the calculating models of normal and tangential stiffness and damping which employ the surface pressure and area as variables are founded for the situation of large area contact. The results show that the effect of the surface pressure on the tangential dynamic characteristics is significantly stronger than that of normal dynamic characteristic function.(4) Engineering application and engineering verification of the empirical formula has been processed. And the finite element model of machine tool bed and column is constructed. The experiment shows the average difference of natural frequencies between computing modes and the measured modes is no more than 7.4%. This result can meet the requirements of engineering application.