For the analysis of vibration modes and dyanmics of assemblies, the normal contact stiffness between two contact surfaces are always ignored for difficulties to treat, though it affacts the final calculation results greatly. This paper studied influences of the normal contact stiffness between the two contact surfaces of the assembly on its vibration modes based on the finite element analysis (FEA) modeling method. First, the relations between the normal contact stiffness and the contact roughness parameters of the two contact surfaces and the contact stress were derived based on the theory of contact mechanics. Then, an FEA modeling method to simulate normal contact stiffness by altering solid elements’ elasticity modulus was discussed. In the end, the differences of vibration modes for the case that the normal contact stiffness was taken into account and the case the normal contact stiffness was ignored. It’s proved that the calculated results for the equivalent FEA model which takes into account normal contact stiffness is almost the same with the analytic solutions. The calculated results for the integer FEA model which disregards the contact stiffness is of great difference with the analytic solutions, and the differences are normally exceeding 10%. The lower for the frequencies, the greater the differences are. And in addition, the vibration modals with considering contact stiffness are changed obviously. The proposed finite method in the paper is suitable for analyzing the influence of normal contact stiffness to assembly’s vibration modes.
AI Yan-ting;Zhai Xue;Wang Zhi;Qiao Yong-li.
Investigation on the Influences of the Normal Contact Stiffness to Assembly’s Vibration Modes [J]. Journal of Vibration and Shock, 2012, 31(6): 171-174
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