Instantaneous and local wavenumber estimations for damage quantification in composites

The continued and expanded use of composite materials in aerospace applications necessitates structural health monitoring and/or nondestructive evaluation techniques that can provide quantitative and detailed damage information for layered plate-like components (such as composite laminates). Guided wavefield methods are at the basis of a number of promising techniques for the detection and the characterization of damage in plate-like structures. Among the processing techniques that have been proposed for guided wavefield analysis, the estimation of instantaneous and local wavenumbers can lead to effective metrics that quantify the size and the depth of delaminations in composite laminates. This article reports the application of both instantaneous and local wavenumber damage quantification techniques to guided wavefield data for delaminated composite laminates. The techniques are applied to experimental data for a simple single delamination case and to simulated data for a more complex multi-ply delamination case. The two techniques are compared in terms of accuracy in damage characterization and computational demand. The proposed methodologies can be considered as steps toward a hybrid structural health monitoring/nondestructive evaluation approach for damage assessment in composites.