A Comparison of Different Excitation Sources in Inspection of Fiber-Reinforced Sandwich Structures Having Light-Weighted Non-Metallic Cores with Thermography and Relative Post-Processing

Thanks to the recent improvements in the post-processing algorithms of different thermography techniques, the effect of different thermal excitations on the inspection results requires a scrutinization for the newly-developed sandwich structures having non-metallic cores. In this study, the researchers have compared the effect of optical-excited thermography, joint-scanning eddy-current thermography, and vibrothermograph on the inspection of fiber-reinforced sandwich structures having light-weighted non-metallic cores by using phase-locked restored pseudo heat flux(RPHF), joint-scanning reconstruction and principal(PCA) component analysis correspondingly. Our experimental results show that optical-excited thermography performs best in number of detected defects however cost the longest inspection time. The reconstructed joint-scanning thermography performs a moderate heating efficiency and less detected defects than the former one on the specimens we have tested. Vibrothermography performs least since vibration is quickly damped in such structure. Moreover, it’s found that phase-locked RPHF should be adapted its assumption to the sandwich structure for a better even performance.