连接结构局部状态改变所致波模态转换特性的数值分析方法

A promising indicator was presented to identify connection states. A numerical method was proposed to compute the wave conversion induced by the local change of the connection joint. The cylinder with a flange was used as an example. The Zhong-Williams scheme was extended to resolve the repeated-root wave shapes by developing an iterative method based on the inverse power method. In combination with the finite element model of the flange joint, the general steps were introduced to construct a diffusion matrix. The dispersion curves and the forced responses were subsequently employed to verify the numerical accuracy of the proposed method and the diffusion matrix. Finally, propagating waves with a circumferent wavenumber of 0—8 were entered into the joint. The local changes allowed for reducing the elastic modulus of the bolts for simplicity. Results showed that the variations in a single bolt, adjacent bolts, and diagonal bolts can convert the energy from the incident waves to some propagating and evanescent waves. The amplitudes of the converted waves increased up to 36 times. It indicated that wave conversion is a promising indicator to monitor the local statuses of joint structures.