Defect detection using the identification of resonance frequency by spatial spectral entropy for noncontact acoustic inspection method
* Presenting author
Our noncontact acoustic inspection enables detection of internal defects of composite material from remote location. The surface to be measured is excited with aerial sound waves. And a two-dimensional vibration velocity distribution is measured using a laser Doppler vibrometer (LDV). Then, signal analysis is performed. In addition to the conventional method, by introducing spatial spectral entropy (SSE), resonance frequency of internal defects can be detected. And at the same time, resonance frequency of a laser Doppler vibrometer can also be detected. By identifying them and choosing the resonance frequencies and visualizing, it is possible to visualize internal defects clearly. Actually, by experimental results using concrete specimens with a crack defect, it became clear that by SSE analysis it is possible to clearly distinguish the resonance of defective part and the resonance of LDV.