Investigations on pulse compression favourable thermal imaging approaches for characterisation of glass fibre-reinforce polymers

Abstract

Active infrared imaging is one of the promising remote and whole field characterisation techniques for non-destructive testing and evaluation of various solids irrespective of their electrical and magnetic prosperities. This technique relies on a mapping of thermal response for a predefined incident heat flux over the test object to detect the presence of surface and subsurface anomalies. Due to its fast, non-contact, safe and quantitative testing capabilities, infrared thermography has gained significant importance in the testing of fibre reinforced polymers. This Letter highlights testing and evaluation of glass fibre-reinforced polymer (GFRP) specimen for detection of subsurface hidden defects using pulse compression favourable thermal wave imaging techniques (for an imposed digitised chirp as well as a 7-bit Barker coded modulated heat fluxes over the test specimen). Further depth scanning capabilities of the proposed schemes have been compared using a timedomain pulse compression based approach. Proposed analytical, as well as simulation studies, have been validated with the experimental results on GFRP material having flat bottom holes as defects.