Effect of fabric combination on IRT-based defect detection in GFRP ship structures

To achieve high-precision infrared thermography (IRT) inspection of composite hull structures, it is essential to understand how fabric characteristics influence IRT performance. This study examines the effects of two fabric combinations—chopped strand mat (CSM) as a single-fabric material and a combination of CSM and woven roving (WR)—on the IRT behavior of glass fiber reinforced plastic (GFRP) hull laminates. Specimens with artificial defects were fabricated using the hand lay-up method. IRT experiments were performed under varying heating times (5, 7, and 10 min) and temperatures (60°C, 65°C, and 70°C), and the results were analyzed using statistical techniques. For the CSM + WR combined-fabric laminates, optimal defect detection occurred at 60°C, whereas for the CSM single-fabric laminates, a higher temperature of 70°C was required. This variation indicates that CSM-only laminates pose greater challenges for IRT-based inspection. The findings underscore the importance of fabric combination in determining appropriate IRT conditions for effective defect detection in GFRP hull structures.