ABSTRACT
This paper describes the use of laser vibrometry and thermal non-destructive testing for detecting defects in GFRP composite by applying a single test procedure. The laser vibrometry involves the averaging of vibration amplitudes over an entire frequency spectrum accompanied by the frequency-phase analysis. Such procedure may lead to suppression of low signals, produced by smaller and deeper defects, by higher signals conditioned by larger and shallower defects. The fusion of results obtained with both laser vibrometry and thermal NDT was used to enhance defect detectability. The corresponding experimental techniques were applied to detecting four types of defects (air gaps, foam, blank grooves, resin) in GFRP composite, as well as evaluating defect size and depth. Also, laser vibrometry was used to characterise barely visible impact damage in CFRP composite, and test data was compared with C-scan ultrasonic inspection results. It has been shown that the results supplied by three inspection techniques have been reasonably consistent in characterisation of defect lateral area and depth. When analysing the complex structure of impact damage in composites, the detection of both shallow and deep defects can also be enhanced by performing fusion of test results supplied by laser vibrometry and active thermal NDT.
Acknowledgements
This study was supported by Russian Foundation for Basic Research grant 19-29-13004 (laser vibrometry), the Russian Science Foundation grant no. 22-19-00103 (thermal NDT results), as well as by Tomsk Polytechnic University Development Program Grant ‘Priority 2030-NIP-EB-008-0000-2022’ (scientific equipment).
Disclosure statement
No potential conflict of interest was reported by the author(s).