CAJ | 학술논문

由于超声波能穿透闭合型裂纹界面，采用传统的线性超声技术难以检测和定位闭合型裂纹损伤，基于非线性时间反转理论研究了闭合型裂纹损伤检测方法。通过金属铝板上黏贴的压电激励／传感阵列，进行了 Lamb 波检测螺栓模拟的闭合型裂纹实验。根据 Lamb 波时间反转原理，得到激励重构信号。通过计算激励信号和重构信号间的相关系数定义了损伤指数，开发了能定位闭合型裂纹的成像算法。实验结果表明非线性超声时间反转方法能够有效地识别非线性的闭合型裂纹。
유우초성파능천투폐합형렬문계면，채용전통적선성초성기술난이검측화정위폐합형렬문손상，기우비선성시간반전이론연구료폐합형렬문손상검측방법。통과금속려판상점첩적압전격려／전감진렬，진행료 Lamb 파검측라전모의적폐합형렬문실험。근거 Lamb 파시간반전원리，득도격려중구신호。통과계산격려신호화중구신호간적상관계수정의료손상지수，개발료능정위폐합형렬문적성상산법。실험결과표명비선성초성시간반전방법능구유효지식별비선성적폐합형렬문。
Initial cracks in metallic structures incline to be closed at rest.Such incipient damage generally fails to be detected and located with traditional linear ultrasonic techniques because ultrasonic waves can penetrate the contact interface of closed cracks.An imaging algorithm based on nonlinear ultrasonic time reversal method was proposed to detect closed cracks in aluminum plates.Two surface-bonded piezoelectric transducer (PZT)arrays were used to generate, receive and re-emitted ultrasonic wave signals.The closed crack was simulated by tightening a bolt on the aluminum plate.By applying large amplitude excitation voltage on the PZT transducers,the closed crack could be opened and closed.The signals of transmitted waves recorded by PZT array,containing nonlinear components,were time reversed, emitted back,and the tone burst reconstructions were achieved.The correlation coefficient between the original excitation signal and the reconstructed signal was calculated to define the damage index for individual sensing path,and was further used to develop an imaging algorithm to locate the closed crack on the plate.The experimental results demonstrate that incident wave signals and their reconstructed signals can be used to accurately detect and locate closed cracks.