Assessing the Feasibility of Monitoring Strain in Historical Tapestries Using Digital Image Correlation

Abstract:  Digital image correlation (DIC) is used to monitor strain in a representative textile material and an historic tapestry. The validity of a 'map function' that allows 3D DIC displacement measurements to be obtained when the reference data are collected with a camera set-up different from that of the deformed data is assessed. An experiment was devised to study the effects of DIC processing parameters (interrogation cell size and overlap) on strain measurements, and to investigate if the textile contains adequate contrast for DIC to operate. The study shows that the textile's weave pattern can be used as the device for correlation. Long-term tests for monitoring creep strain using DIC both in the laboratory and in situ are presented. The results show good correspondence between strain changes in the tapestry and relative humidity.