Crack localization in plate-like metallic structures using vibration modulated guided waves

Abstract

Abstract This paper proposes a method for crack localization in plate-like metallic structures with nonlinear vibration modulated guided waves. A spatially distributed piezoceramic transducer array is used to introduce a low-frequency modal vibration and a high-frequency ultrasonic tone burst into a metallic plate, and the responses are also acquired by the array. Due to the semi-broadband property and similar propagating speed, the nonlinear waves generated from the damage and the linear waves from other structural features overlap both in time and frequency in the acquired response signals. It is difficult to separate them by filtering method, which affects the damage localization result. The conventional pulse inversion technique is extended to extract the nonlinear signals, and then a delay-and-sum imaging method based on the Wigner-Ville distribution is applied to the extracted signals to construct a damage image. The proposed method is experimentally investigated to localize a fatigue crack near a drilled hole in an aluminium plate. The results demonstrate that the fatigue crack is localized accurately and is also distinguished from linear scatters by use of the proposed method.