Quantitative Nonlinear Ultrasonic Spectroscopy for Imperfect Interfaces and Imperfect Bonding by Guided Waves

在具有接触界面或黏着界面的平板上激发高幅值兰姆波，通过时频分析分析其传播波形，提取其高次谐波等非线性频谱分量。结果发现，谐波分量的振幅随接触或粘接条件的变化而变化。因此，非线性兰姆波特性有希望作为评估板接触或粘接条件的工具。从理论角度出发，利用Mindlin板理论和非线性界面模型研究了弯曲波的传播。此外，根据兰姆波的色散关系，推导了兰姆波谐波累积增长的条件。

High-amplitude Lamb waves were excited on plates with contact or adhesive interfaces, and the propagated waveforms were analyzed by the time-frequency analysis to extract the nonlinear spectral components such as higher harmonics. As a result, the harmonic components were found to change their amplitude depending on the contact or adhesive conditions. Therefore, nonlinear Lamb wave characteristics are promising as a tool for evaluating the contact or adhesive conditions of plates. From a theoretical point of view, the flexural wave propagation was examined based on the Mindlin plate theory with nonlinear interface model. Furthermore, the conditions for cumulative growth of Lamb wave harmonics were derived based on the dispersion relation of Lamb waves.