Visualization of defects in thin metal plates by a scanning airborne ultrasound source technique using guided waves of different frequencies

Abstract

A scanning airborne ultrasound source technique was developed to overcome the riskiness of laser ultrasound, which uses an ultrasound source that has a fixed sound wave focusing point and thus requires mechanical motion for sound source scanning. Therefore, the measurement time becomes longer. To solve this problem, we have proposed a method of simultaneously exciting many measurement points in the target using focused ultrasound sources of different frequencies. In this paper, we investigated the visualization of defects in a thin metal plate by the scanning elastic wave source technique using an airborne ultrasound source driven at two frequencies. When the testing was performed using two frequencies, either frequency visualized the defects.

Multi-mode 3D ultrasonic phased array imaging method using piezoelectric and laser ultrasonic system (PLUS)

“…To avoid catastrophic accidents, the reliable and accurate nondestructive measurement of cracks is indispensable. Among various nondestructive testing (NDT) methods, ultrasonic testing (UT) [1][2][3][4][5][6][7] is one of the most practical methods for internal defects since UT is highly sensitive to cracks. 1,8,9) Although conventional UT was based on the measurement of defect echo, ultrasonic phased array (PA) has recently become one of the primary means in industrial fields because of its excellent imaging capability.…”

Lamb wave pulse compression in airborne ultrasound excitation

“…We have proposed a high-speed non-contact non-destructive testing [1] method for defects in thin metal plates using an Airborne Ultrasound Phased Array [2][3][4] (AUPA) [5][6][7]. The ultrasound emitters of the AUPA generally have a high quality factor and a narrow frequency band, so the emitted sound waves have a time width that is several tens of times that of the input signal.…”

“…Such a long-time transmission wave causes multiple scattering inside the testing target. Therefore, it is difficult to identify the defect from the received waveform, [8][9][10] and it is not suitable for non-destructive target.…”

Aerial intense ultrasonic source integrating the horn and vibrating plate

“…These uses depend on using powerful ultrasonic waves generated in air to induce physical actions. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Thus, a sound source for generating intense ultrasonic waves is required.…”