Abstract:
InfraRed non-destructive testing and evaluation (IRNDT&E) has
emerged as a promising approach for non-destructive testing and
evaluation (NDT&E) of various materials because of its inherent
merits such as remote, non-invasive, qualitative as well as quantitative
inspection capabilities. Among the various IRNDT&E techniques,
recently proposed modulated pulse compression favourable thermal
wave imaging (PCTWI) techniques, especially frequency modulated
thermal wave imaging (FMTWI) and its digitised version digitised
FMTWI (DFMTWI) have gained popularity over the conventional
sinusoidal modulated [lock-in thermography (LT)] and pulse-based
thermographic techniques [pulse thermography (PT) and pulse phase
thermography (PPT)] by providing better depth resolution, in less
experimentation time, using low peak power excitation heat sources.
The present work highlights a comparative study on highly depth
resolved continuous depth scanning PCTWI techniques, with single
frequency thermal excited LT, on the basis of defect detection probability. The proposed study has been carried out on a glass fibre
reinforced polymer test sample with Teflon inserts as defects by considering peak side lobe ratio as a figure of merit. The experimental
results clearly show that the probability of detection of defects for
DFMTWI is far superior as compared to FMTWI and LT.
