【摘要】 对金属板结构使用过程中产生的微裂纹进行非线性Lamb波混频检测的相关研究.用压电晶片在铝板中激励Lamb波,选取合适模态的Lamb波与微裂纹间的非线性相互作用,并用损伤指数评估非线性Lamb波混频强度与裂纹相互作用间的关系.在板上不同位置布置压电晶片,分析影响非线性Lamb波混频强度的因素.实验结果表明,S₀模态的Lamb波与裂纹相互作用时,差频信号比和频信号明显;同时混频的强度受波强度、波入射方向以及衍射角等因素影响.更多还原

【Abstract】 A novel damage detecting method based on nonlinear frequency mixing of Lamb wave is employed for detecting micro-crack in metal plates. The Lamb wave was excited by piezo-ceramics wafers. The nonlinear interaction between the optimal Lamb wave modes and micro-crack was studied. The damage index was established to evaluate the frequency-mixing intensity induced by the nonlinear behavior. Furthermore, the factors influencing the frequency mixing of Lamb wave were also analyzed. The results show that the differential frequency signal is more obvious than the sum frequency signal in the received signal when the S₀ mode Lamb wave interacts with the micro-crack. The intensity of frequency mixing is affected by the amplitude, incidence angle and diffraction angle of Lamb wave.更多还原