Testing and Evaluation of Glass Fibre Reinforced Polymer Using Principal Component Thermography

Non-Destructive Testing and Evaluation (NDT&E) is being developed across various segments of the industry for detecting the presence of defects occurring either during the manufacturing or its in-service stage such as cracks, holes, delamination, etc. in a wide variety of materials. Among various NDT&E methodologies, InfraRed Thermography (IRT) gained importance due to its remote, whole-field, safe, and quantitative assessment of industrial materials. These merits make the IRT a promising approach for the inspection and evaluation of various composite structures widely used in aerospace and defence applications. Especially the usage of Glass Fiber-Reinforced Polymers (GFRP) in the shipbuilding industry gained popularity due to its high strength-to-weight ratio, low cost, and improved sustainability, unlike metals. The present work highlights the suitability of Principal Component Analysis (PCA) for processing thermal data obtained from the Frequency Modulated Thermal Wave Imaging (FMTWI) to test and evaluate artificially simulated blind hole defects in a GFRP material. The proposed approach highlights the merits of the data-reduction features of the PCA along with its defect detection capabilities by considering the optimal principal component. Further, the results presented in this manuscript will enhance the scope of PCA-based IRT named Principal Component Thermography (PCT) and its applications for sub-surface defect detection and evaluation for the characterization of a variety of materials such as metals, semiconductors, and composites.