A Global Digital Image Correlation Enhanced Full-Field Bulge Test Method

The miniature bulge test is a known method for characterizing the full stress-strain response of freestanding thin films. However, some discrepancies between quantitative results in the literature may be attributed to erroneous assumptions on the bulge shape. In this research, a specialized global Digital Image Correlation technique is developed that circumvents the need for bulge shape assumptions by correlating directly high-resolution profilometry maps of bulged membranes to yield full-field continuous displacement maps, from which local strain maps can be computed. Additionally, local curvature maps are also derived.