Quantitative characterization of resistive defects in thick compositesusing step heating thermography

摘要

Inspection of thick composite structures, such as Reinforced Thermosetting Resin (RTR) pipes used in the petroleum industry, using infrared thermography is difficult. This paper investigates the use of step heating thermography to increase the maximum detectable defect depth and describes techniques to quantitatively characterize defect depth and severity in thick composites. A procedure to simultaneously determine defect depth and thermal resistance from the early time surface temperature is described. The procedure is based on fitting the early time surface temperature profile over a defect to a one-dimensional three-layer analytical model. Experimental testing demonstrates the accuracy of the procedure.