Non-contact harmonic imaging of crack in acryl plate by using high intensity aerial ultrasonic wave and laser Doppler vibrometer

摘要

We have been studied a nondestructive inspection of crack using high-intensity aerial ultrasonic wave and laser Doppler vibrometer(LDV). In this method, cracks are imaged from the vibration velocity distribution including the health part by non-contact measurement of the vibration velocity of the target surface excited by sound wave. Generally, in order to detect cracks, it is necessary to use a high frequency ultrasonic waves. However, there is a problem of distance attenuation. Therefore, we propose to use a high inetensity aerial ultrasonic waves and attempt to detect cracks by using higher order frequencies generated by the nonlinearity.