Thermographic Digital Image Correlation (TDIC) Measurements of Mechanically-Loaded Structures

Abstract

This research examined the use of Thermographic Digital Image Correlation (TDIC) in fire testing with flames in the field of view. The error and uncertainty in the deformation measurements obtained via TDIC with fire in the field of view were reduced by ensuring the grayscale histogram of the CCD images was neither under-saturated nor oversaturated once fire was present. Quantitatively, this corresponded to the greyscale histogram having a mean value between 13-91 out of 255 and a kurtosis between 2.7-10.7 without the fire present. Results obtained from testing using this setup were found to reduce data loss due to overexposure when compared to results obtained using arbitrary light conditions. Thus, future investigators may reduce the error in the system for live fire testing before exposing the sample to fire by setting up lighting and camera settings to obtain histograms in this range.