Source patterning in time-resolved infrared radiometry of composite structures

A quantitative thermographic NDE technique for the characterization of composite materials is under development along with supporting theoretical analysis. The TRIR technique differs from other pulsed thermography techniques in that the surface temperature of the specimen is monitored as a function of time during the application of a step heating pulse to the sample. Full-field images with temporal resolution faster than video frame rates are acquired with an infrared scanner by disabling the vertical galvanometer in the infrared camera and scanning the heating source across the sample. Alternatively, an InSb focal plane array is used to acquire the time-resolved images. The geometry of the heating source is selected to optimize the acquisition of information about the structure of composite materials. Experimental results in both simple and hybrid composite systems are discussed. The depth and lateral extent of interlaminar separation in composites subjected to impact loading are presented and the use of lateral heat flow techniques to image vertical defect structures is examined.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.