Feasibility studies on microwave heating for nondestructive evaluation of glass fibre reinforced plastic composites

Recent developments in non-destructive evaluation (NDE) have concentrated in two directions: 1) sensors and arrays for local material/defect detection at both macro and/or micro levels; 2) large-scale component imaging and monitoring such as thermography. In this paper, microwave heating is proposed for defect detection of glass fibre reinforced plastic (GFRP) composite material in far field. Such system using rectangular waveguide as illumination device is implemented and compared via both numerical simulation and experiment. In experiment, a GFRP wind turbine blade is chosen as test sample. Results for GFRP blade from simulation and experiment show that heat is accumulated at defect edge regions. This phenomenon enables defect detection using microwave heating. To achieve better contract of heat patterns at defect and non-defect region, a high power heating system is proposed. Simulation and experimental results show the feasibility of the system for defect detection with enough heat generation.