

Image Processing Technique for Vibrothermographic Field Tests
Abstract
The paper investigates the aspects of image processing in vibrothermographic measurements applied to the inspection of composite plate and carbon steel weld test specimens. A carbon epoxy prepreg plate with barely visible impact damage and carbon steel weld test specimens have been tested with use of a handheld ultrasonic excitation device. Due to varying contact pressure and misalignment between the sonotrode and the test piece the intensity of excitation is fluctuating with time. As a solution to this problem the authors propose the image processing technique based on a two dimensional Fourier transform of the infrared images. The technique allows to increase the quality and readability of the results coming from a vibrothermographic measurement with poor ultrasonic excitation