Application of Active Microwave Thermography to Inspection of Carbon Fiber Reinforced Composites

Inspection of carbon fiber reinforced polymer (CFRP) composites is very important in the aeronautical and transportation industries. Many nondestructive testing (NDT) techniques have been applied for health monitoring including ultrasound, thermography, etc. Although thermography has been widely used for this purpose, it often requires powerful heat lamps which may increase the risk of (thermal) damage to the structure under test. Thus, hybrid NDT methods have also been developed. Recently, the integration of microwave heating and thermography, herein referred to as Active Microwave Thermography (AMT), has also been considered as a potential health monitoring tool for infrastructure. This hybrid method uses microwave energy to heat a structure of interest, and subsequently the thermal surface profile is measured using a thermal camera. This paper investigates the potential of AMT for inspection of CFRP-rehabilitated airframes. Preliminary simulations and measurements indicate that AMT has the potential to detect disbonds under carbon fiber patches bonded to aluminum.