基于非线性动响应的夹持松动特性研究

Study on the Characteristic of Clamped Looseness Based on Nonlinear Dynamic Response

根据夹持结构存在的局部非线性特点,研究基于非线性动响应的夹持松动识别方法。利用悬臂梁结构在夹持边界条件下自由振动的非线性动响应理论解,将结构非线性响应的二次谐波振幅与基频振幅响应的比例系数r作为松动判别特征量,研究夹持结构的松动特性规律。以夹持悬臂梁结构为研究对象,建立接触有限元模型来计算夹持结构的非线性动响应;同时开展了试验研究,通过不同夹持力下结构振动响应特性来验证该方法的有效性。仿真和试验结果表明,随着夹持力的增加,结构非线性动响应信号的二次谐波振幅呈下降趋势,振幅比值r呈幂指数下降。二次谐波振幅与基频振幅的比值r可以作为表征结构松动状态的判据。

Looseness identification of clamped structures based on nonlinear dynamic response is investigated in this paper,according to local nonlinearities in clamped structures.The theoretical solution of the nonlinear free vibration of a cantilever beam is utilized with clamped boundary conditions.The ratio between the second harmonic and the fundamental frequency amplitudesis denoted as r,which is a characteristic quantity to investigate the loosening laws of clamped structures.Aiming at the clamped beam,the nonlinear dynamic response is solved by the contact finite element model.Meanwhile,characteristics of the dynamic responses are analyzed based on structural experiments with different clamping force to verify the method.Numerical and experimental results show that the second harmonic amplitude of the nonlinear response decreases when the clamping force increases,and ralso decreases with the increasing the clamping force,according to the exponent relationship of the power.Therefore,ris an effective characteristic quantity for identifying the state of clamped structure.