法向接触刚度对装配体振动模态影响的研究

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在对装配体进行模态分析时,装配体接触面间的法向接触刚度对计算结果具有很大影响,但在实际中由于处理困难却往往被忽略。基于有限元建模方法分析了装配体接触面法向接触刚度对装配体振动模态的影响。首先,根据接触力学理论推导了法向接触刚度与接触表面粗糙度和接触应力之间的关系;然后,探讨了通过改变层单元弹性模量来模拟法向接触刚度的有限元建模方法;最后,通过算例分析了考虑与不考虑接触刚度时振动模态的差异。研究结果表明,考虑法向接触刚度的有限元等效模型计算结果与解析解非常接近,不考虑接触刚度的整体模型计算结果与解析解相差较大,一般超过了10以上,且频率越低差异越大,另外振型也有明显差异。建立的有限元模型可用于研究法向接触刚度对装配体振动模态的影响。 For analysis of vibration modes and dyanmics of assemblies,normal contact stiffness between two contact surfaces is always ignored due to difficulties of treatment,in fact,it affacts final calculation results greatly.Here,influences of normal contact stiffness between two contact surfaces of an assembly on its vibration modes were studied based on the finite element（FE） modeling method.Firstly,the relations between normal contact stiffness and contact roughness parameters of two contact surfaces,and the contact stress were derived based on the theory of contact mechanics.Then,a FE modeling method to simulate normal contact stiffness by altering solid elements＇ elasticity modulus was explored.In the end,the differences of vibration modes considering normal contact stiffness and ignoring that were analyzed.It was shown that the calculated results of the equivalent FE model considering normal contact stiffness are almost the same as the analytic solutions;the calculated results of the FE model ignoring contact stiffness is of great difference to the analytic solutions,and the differences are normally above 10%;the lower the frequencies,the greater the differences;in addition,the vibration modal shapes considering contact stiffness are changed obviously;the proposed FE model is suitable for analyzing influence of normal contact stiffness on an assembly＇s vibration modes.