Nondestructive evaluation of FRP composite members using infrared thermography.

摘要

The objective of this research is to establish infrared thermography as an effective tool for nondestructive evaluation of structural members made of fiber reinforced polymer (FRP) composite materials. The applicability of this method for the detection of subsurface anomalies such as voids, cracks, debonding, and delaminations in concrete bridge decks and pavements and in some configurations of FRP decks has been studied earlier by other researchers. These earlier studies have yielded reasonably satisfactory results though further refinement of the methodology and improvements in the image processing techniques were recommended.; To enhance the effectiveness of the infrared thermography technique, it is important to improve and quantify the contrast in the thermal images. This enables the thermographer to arrive at better conclusions including quantitative estimation of the defect depth. Different methods for analysis of digital infrared images suggested by various researchers were reviewed in this study and recommendations were made for evaluating their applicability for mass-produced FRP composite structural components.; Infrared thermography tests were conducted in the laboratory on various FRP specimens with built-in delaminations. The results showed that the infrared technique can be developed for long term monitoring of FRP structural components. As a part of this research, a field trip was also conducted for detecting the presence of delaminations/debondings in FRP wrapped reinforced concrete bridge columns using infrared thermography. In the field tests, it was possible to detect the locations of delaminations/debondings. These results were in agreement with the tapping test results.