Passive-Only Defect Detection and Imaging in Composites Using Diffuse Fields

A wave-based passive approach is here presented to detect damage in composite materials subjected to diffuse wave fields. This is the case, for example, of wind turbine blades subjected to random air-structure interaction loads in operation. The known reconstruction of the Green’s function from cross-correlations of diffuse fields is first performed. A first approach, based on wave reciprocity applied to the passively reconstructed Greens function, is first proposed to detect damage located along the straight path between two sensors. A second approach, based on matched field processing applied to the passively reconstructed Green’s function, is then proposed to detect and locate damage anywhere in the structure. These techniques are suitable for structural health monitoring of structures subjected to random dynamic loads from operational environments such as wind turbines, aircraft, bridges, marine structures, etc.