Abstract: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 penetrate the contact area of the closed crack. In this paper, an imaging algorithm based on nonlinear ultrasonic time reversal method is proposed to detect closed cracks in aluminum plates. Two surface-bonded piezoelectric transducer arrays are used to generate, receive and re-emitted ultrasonic wave signals. The closed crack is 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 transmitted waves recorded by PZT array contain nonlinear components, the signals are time reversed, emitted back, and the tone burst reconstructions are achieved. The correlation coefficient between the original excitation signal and the reconstructed signal is calculated to define the damage index for individual sensing path, and are 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.
张望,吴维亮,肖黎,屈文忠. 闭合型裂纹时间反转损伤识别[J]. 振动与冲击, 2015, 34(9): 95-101.
Wang ZHANG, Weiliang WU, Li XIAO, Wenzhong QU. Time reversal based damage detection for closed crack. JOURNAL OF VIBRATION AND SHOCK, 2015, 34(9): 95-101.
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