The influence of the natural frequency and the type of excitation signal on damage detection when analyzing the temperature profile generated on the surface of sandwich beams

Abstract Vibrothermography is a non-destructive technique used to detect structural damage, following specific application guidelines. Classified as active infrared thermography, it employs mechanical vibrations to excite the system, utilizing surface thermal mapping to identify temperature profiles or gradients that indicate potential internal defects. Experimental tests allowed for the characterization of the structure’s intrinsic properties alongside the thermal and mechanical responses of the beams, enabling an analysis of how these parameters affect surface temperature profiles. For the sandwich beam with induced damage at the Rohacell–Prepreg interface, excitation signals combining the first natural frequencies with various waveforms (triangular, square, and sinusoidal) resulted in differences in deformation to length of the beam during excitation. Internal heat generation, coupled with heat transfer to the environment, produced temperature variations of up to 2 °C along the monitored surface. Furthermore, displacements in the damaged beam were up to three times greater than those observed in the undamaged beam at the established reference points.