Testing and evaluation of glass fiber reinforced polymers by thermal wave imaging

Glass Fiber Reinforced Polymer (GFRP) composites are being used in wide range of applications since these materials are less affected by environmental and atmospheric conditions in addition to its high strength to weight ratio. However, there are still some concerns about reinforced polymers due to their manufacturing imperfection or imperfections during their in-service, such as the presence of surface and sub-surface defects which effect their performance. InfraRed Thermography (IRT) shows its potential usage for non-destructive testing and evaluation (NDT&E) due to its intrinsic testing capabilities such as remote, whole field, quantitative and qualitative to detect surface and sub-surface defects. This present work highlights a spectral reshaping by introducing a Gaussian window on the captured thermal profile in a frequency modulated thermal wave imaging and named as Gaussian Windowed Frequency Modulated Thermal Wave Imaging (GWFMTWI) technique. Further various multi-transform techniques (time and frequency domain based) have been introduced in order to test sub-surface defect detection capabilities in chosen GFRP sample. Comparison has been made with the non-stationary linear frequency modulated thermal wave imaging technique in terms of depth scanning capability. Results obtained from the GWFMTWI clearly shows better detection potential with improved test resolution and sensitivity.