Lamb wave tomography technique for crack damage detection

Lamb wave tomography technique is regarded as one of the most effective ways in nondestructive inspection and structural health monitoring (SHM), so that it has attracted lots of attentions. RAPID, namely Reconstruction Algorithm for the Probabilistic Inspection of Damage, is a new kind of tomography technology, which has the unparalleled advantage over other techniques and has simple tomographic parameters computation. However, traditional RAPID technique was not suitable for crack damage imaging. Since RAPID technique is based on the statistical correlation analysis, it is hard to detect the direction of the crack damage. In this paper, the improved RAPID algorithm is developed to detect the crack damage, especially for the crack direction monitoring. The proposed improved RAPID algorithm can determine the direction of the crack by correcting the SDC (signal difference coefficient) values of the sensing paths. The experiments were carried out to validate the improved method and the results shown that that it can detect and evaluate the crack damages effectively in the tomographic images.