Improvement of bonded joint defects visibility by use of selected infrared image processing methods

This paper deals with the problems of adhesively bonded joints quality assessment. Author’s research are focused on development of the specialized method based on active thermography dedicated to detection of flaws in adhesively bonded structures for automotive industry purposes. During the research, a series of active thermography experiments on samples with different defects were performed. The infrared images acquired during the experiments were the basis for development of an IR image processing algorithms allowing to obtain the best defects detectability. Image processing algorithm requires conduction of the following operations: A pre-processing using noise filtration and contrast enhancement operations in order to improve image quality; transformation of spatiotemporal structure of images for further improvement of defects visibility; an image segmentation, image fusion, and pattern recognition for identification and classification of the defects. The paper presents the results of the first step of an infrared image processing algorithm. The algorithm applies multiple methods such as TSR (Thermographic Signal Reconstruction), PCT (Principal Component Thermography) or DTT (Dynamic Thermal Tomography). Obtained results show that algorithm combined TSR and pulse phase thermography is very promising for effective revealing of defects of adhesively bonded joints.