Damage detection and local resonances model in CFRP composite material by vibrothermography

Vibrothermography (VT) is an active non destructive technique able to detect singularities like
delamination, even if the defect internal faces are in contact. Under sonic or ultrasonic mechanical
vibrations, a delamination may behave like a heat source principally due to friction between the rubbing faces and/or stress concentration in the area. The present article focuses on the understanding of the underlying phenomenon so-called "local resonances" and its correlation with the presence of temperature peaks observed at certain frequencies. For this purpose, a simplified finite element modal analysis of the delamination model is compared with the heating rate vs. frequency data's acquired by an infrared camera. Then, some conclusive results of sine sweep and chirp testing will be presented and discussed in regards to this theory.