中文摘要：

针对结构早期损伤超声非线性检测中损伤表征问题，发展了一种基于动态小波指纹的超声信号分析方法，从超声信号的动态小波指纹分布中提取出一种可用于结构早期损伤表征的超声非线性特征参数。研究了小波基函数及分析尺度对超声非线性效应提取效果的影响，优选出对结构早期损伤敏感的小波基函数以及尺度范围。将提出的动态小波指纹分析方法应用于二次谐波及混频非线性超声检测信号分析，结果表明，动态小波指纹分析方法可有效提取出检测信号中的二次谐波及混频分量，基于小波指纹分布的非线性特征参数可用于板结构中微裂纹的定量表征。本文研究工作为结构早期损伤超声非线性检测中的弱非线性效应提取作了有益探索。

英文摘要：

Toward the characterization of early stage damage of structures by nonlinear ultrasonic testing technology, a dynamic wavelet fingerprint （DWFP） analysis method was developed for nonlinear ultrasonic signal analyzing, and nonlinear characterization parameter of early damage based on DWFP distribution was proposed as well. Meanwhile the influence of different wavelet basis functions and scale extents on nonlinear ultrasonic effects extraction is investigated, and the optimal wavelet basis functions and scale extents sensitive to early stage damage are obtained. After that, DWFT analysis method was applied to harmonic and frequency-mixing nonlinear ultrasonic test signals analysis. It has been shown that DWFT analysis method can effectively extract the harmonic and frequency-mixing components embedded in testing signals, and nonlinear characterization parameter based on DWFP distribution is capable of quantifying characterization of micro-crack in plate structures. Useful exploration is done for nonlinear ultrasonic testing signal analysis.