Breathing crack detection using Lamb wave and DORT method

Abstract

Most of the members of modern structures operate under loading conditions, which may cause damages or cracks. Interest in detecting structural damage, at the earliest possible stage (i.e. breathing crack), has always been a major issue in the structural health monitoring community. Among structural health monitoring techniques, Lamb waves is frequently used as diagnostic tools to detect damage in plate-like structures. The decomposition of the time reversal operator (DORT) method is a selective detection and focusing technique using an array of transmit-receive transducers. But there is little research on locating breathing crack on the plate using Lamb wave DORT method. In this paper, a proposed approach based on the DORT method is developed to locate a simulated breathing crack on the aluminum plate using Lamb wave through finite element simulation on the commercial finite element code ANSYS platform. The nonlinear superharmonic, generated by a breathing crack under the effect of an external Lamb wave interrogation signal, was related to the location of the crack. This method, which uses PZT array and operates under multi-modes pulse-echo mode, can estimate the position of the breathing crack in 2D image by numerically backpropagating selective eigenvector using the S0 Lamb wave propagation analytical solution. The numerical simulation results illustrate the proposed method.