中文摘要：

对材料和结构进行无损检测和评价在其全生命周期中非常重要。超声检测是一种重要方法,但传统线性超声观察时域信号,受波长等因素所限,对于微缺陷、微裂纹以及如粘接、分层等界面缺陷不敏感,同时对于金属疲劳等力学性能退化尚缺乏有效评价手段。近年来,基于超声的非线性效应,如高次谐波及次谐波的产生、波束混叠以及谐振频率的改变等而发展的非线性超声无损检测和评价方法主要从频域分析信号特征,进行缺陷判别,对于克服传统超声的不足具有积极的意义,是传统线性超声检测手段的有效补充。从由不同的声学非线性效应而衍生的检测方法出发,介绍非线性超声无损检测技术的研究和发展现状,总结其中的关键技术和问题,并对未来发展做出思考。

英文摘要：

It is important to conduct nondestructive testing and evaluation on structures and materials during their working life cycles.Ultrasonic testing（UT） is a key method,but conventional UT methods observe the received signal in time domain and are not suitable for detecting micro-defects,micro-cracks,and interface defects such as bonding and delamination,nor are they efficient at detecting metal fatigue and degradation defects because of the limitation of their wavelength.In recent years,based on nonlinear ultrasonic effects,such as high-order harmonic generation,sub-harmonics,beam mixing and shift of resonant frequency,nonlinear ultrasonic testing and evaluation techniques which analyze the signal characteristics mainly from frequency domain are developed.The nonlinear ultrasonic technique has a promising future to overcome the shortages of conventional UT techniques.The different nonlinear ultrasonic techniques based on different nonlinear acoustic effects are reviewed,the key techniques of nonlinear ultrasonic testing are summarized,and their future development is predicted.