Two ways in which the concept of open resonator can be used in connection with nondestructive evaluation will be described. In the first, a noncontact transducer’s efficiency of transferring energy into an object can be increased by utilizing the resonance of the gap between the transducer and object. By choosing the gap distance, frequency and transducer width a resonant wave appears which will have a considerably larger amplitude at the object surface.
Secondly, by fitting the critical parameters of open resonators for thin objects, like extended plates, the wave field inside the object can be localized. Thus some Nonlinear Elastic Wave Spectroscopy methods may be used to determine the location of damage.
Author: Claes Hedberg, Sven Arnoldsson, Rikard Gunnarsson
Source: Blekinge Institute of Technology