Vibrothermography using vibration modes

Rodriguez, Samuel; Universite de Bordeaux; France

Meziane, A.; Université de Bordeaux; France
Pradère, C.; CNRS; France
Rodriquez, S.; Université de Bordeaux; France

ID: ECNDT-0245-2018
Session: Thermography and Thermosonics 2
Room: H1
Date: 2018-06-14
Time: 11:10 - 11:30

The present work deals with the temperature monitoring of a viscoelastic planar structure submitted to flexural vibrations. In such materials heat sources are generated when submitted to mechanical stresses. This phenomenon has been studied and used for NDT purposes with low frequency ultrasonic compressional and flexural waves (typically from tens to hundreds kHz). Here, the excitation is provided in the audible frequency range so that the first flexural modes of the structure are excited. The center of the plate is clamped to a shaker that provides a mechanical sinusoidal excitation at a frequency corresponding to a chosen vibration mode. The heat source pattern appear to be depending on the vibration pattern of the structure, it is to say, on the mode shape. The underlying phenomenon is studied both experimentally and numerically with an anisotropic plastic plate. Extra effort has been made to measure both the mechanical and the thermic properties of the sample in order to simulate the complete behavior of the structure. Experimental and numerical results are in good agreement. This excitation technic offers perspectives for the localization of defects in large structures.