Surface damage detection of steel plate with different depths based on Lamb wave

A new experimental procedure for damage detection based on active acoustic emission was developed which is sensitive to damage depth. Two new damage indexes were proposed by analyzing the amplitudes of low-frequency signal direct wave and high-frequency signal maximum component. The relations between damage depths of a steel plate and damage indexes were studied through numerical simulation considering different signal-to-noise ratios (SNR). It was found that the values of the damage indexes increased with the depth of damage, and the stability of the indexes was further analyzed by the coefficient of variation (Cov). Damage detection experiments for steel plates with different damage depths were carried out, and the results showed good agreement with the numerical simulation which further verifies the feasibility of the proposed method. The present method can provide basis for the engineering application of damage detection with different depths.