Modified sparse reconstruction imaging of lamb waves for damage quantitative evaluation

Lamb wave based sparse reconstruction imaging is promising for damage localization in structural health monitoring (SHM) and nondestructive testing (NDT). This method requires accurate dictionary construction to match damage reflected Lamb wave signals. Damage is assumed to be a point-like reflector in previous research, however, most structural damages tend to occupy a physical extent within the structure, which limits dictionary accuracy and thus reduce the performance of sparse reconstruction imaging. In this study, dictionary construction is extended to both point-like damage and damage occupying a physical extent, a modified sparse reconstruction imaging method is subsequently proposed based on the extended dictionary. Compared with conventional method, imaging performance of the modified method is improved due to superior dictionary construction. Another advantage of modification is the ability of forming damage outline for quantitative evaluation. The effectiveness of the modified method is experimentally demonstrated with simulated delamination in composite laminates.