CAJ | 학술논문

由于应力作用、撞击以及周期载荷等因素的影响，金属结构中不可避免地产生疲劳裂纹损伤。若结构存在边界非线性，传统的非线性调制方法将无法有效识别疲劳裂纹损伤。针对该问题，提出一种能够避免边界非线性干扰的非线性超声调制方法。该方法采用正弦脉冲信号和持续正弦信号作为激励，通过识别信号之间的非线性调制现象来进行损伤检测。分别以铝制裂纹梁和完整梁为实验对象，粘贴两个压电片作为作动器和传感器，利用短时傅里叶变换对响应信号进行时频分析，提取非线性调制信号成分，对疲劳裂纹损伤进行有效的识别。
유우응력작용、당격이급주기재하등인소적영향，금속결구중불가피면지산생피로렬문손상。약결구존재변계비선성，전통적비선성조제방법장무법유효식별피로렬문손상。침대해문제，제출일충능구피면변계비선성간우적비선성초성조제방법。해방법채용정현맥충신호화지속정현신호작위격려，통과식별신호지간적비선성조제현상래진행손상검측。분별이려제렬문량화완정량위실험대상，점첩량개압전편작위작동기화전감기，이용단시부리협변환대향응신호진행시빈분석，제취비선성조제신호성분，대피로렬문손상진행유효적식별。
Due to the influences of stress,impact and cyclic load,metal structure was likely to generate fatigue crack or other tiny damages.Conventional nonlinear modulation method could not de-tect fatigue crack when the boundary conditions were nonlinear.Herein,a nonlinear ultrasonic modu-lation method was developed to detect a fatigue crack on an aluminum beam,which recognized the modulation of tone burst and high-frequency ultrasonic wave.Intact beam and cracked beam were cho-sen as the subjects for the experiments,two PZTs were boned on the surface of the aluminum beams as the actuator and the sensor.The STFT was used for computing the spectrograms of the response which is acquired by the sensor.The modulations of tone burst and continuous sinusoidal excitation in-dicate the presence of fatigue crack.