中文摘要：

针对金属板结构中微裂纹检测问题,进行基于二次谐波的非线性兰姆波检测方法研究。基于赫兹接触理论,进行板中二次谐波非线性兰姆波理论研究,建立板中兰姆波二次谐波与微裂纹尺寸的关系模型。进行板中微裂纹非线性兰姆波数值仿真,研究不同长度和宽度的微裂纹对兰姆波二次谐波非线性效应的影响。结果表明,随着微裂纹长度增加,二次谐波幅值呈增加趋势;随着微裂纹宽度增加,二次谐波幅值呈减小趋势。在以上研究基础上,进行板中微裂纹非线性兰姆波检测试验研究。结果表明,通过测量结构的兰姆波二次谐波非线性系数,可用于结构中微裂纹检测与定量评价。研究工作为板中微裂纹定量检测做了有益探索。

英文摘要：

For the metal plate structure in micro crack detection problem, the thesis of the second harmonic of the nonlinear Lamb wave detection method research based on. First, the board in the second harmonic nonlinear Lamb wave theory is used to study, analyses the influence of the micro crack width and length of second harmonic excitation efficiency, and through the numerical simulation of nonlinear effect of different length and width of the micro crack and the Lamb wave interaction. The results show that with the increase of micro crack length, the two harmonic amplitude increases and the two harmonic amplitude decreases with the increase of the micro crack width. Based on the above research, the plate crack in nonlinear Lamb wave detection experiments. The results show that by measuring structure of Lamb wave second harmonic nonlinearity coefficient, for structure of micro crack detection and quantitative evaluation. The research work is a useful exploration for the quantitative detection of micro cracks in the plate.