Sliding Spectrum Extraction of simulated elastic waves for damage location in composites

This study investigates different approaches to locate defects in composite structures. This instigation is performed using finite element simulations of 3D propagation of elastic waves in a multi-layer carbon fiber reinforced polymer (CFRP) composite plate. The simulations are analyzed using a well-known 3D Fourier-based technique applied on the calculated wavefields. The wavefields are here the out-of-plan velocity component at the top layer of the composite. These wavefields contain detailed information about the guided waves and the state of the composite structure. A novel Sliding Spectrum Extraction (SSE) algorithm applied on the wavefields is capable of the detecting areas where large changes in the frequency-time Fourier content are observed. These large changes are normally seen in areas with a defect such as delamination. The new Sliding Spectrum Extraction technique is used on wavefields from elastic wave propagation simulations performed on an 8-layer CFRP plate with a delamination defect.