Using Digital Image Correlation Method for Measuring Surface Crack Opening Displacement and Surface Crack Propagation and Crack Tip in Alpha-Alumina

Abstract

There are many techniques were used to measure and observe the surface crack length and surface crack opening displacement (SCOD)at the macro scale but in this study the digital image correlation technique (DIC) is used to measure and obtain the cracks at micro scale and to observe the crack tip. There are many cracks within the microstructure that created during Vickers indentation. The possibility of determining surface crack opening displacement and surface crack length and crack tip in alpha- alumina and determining strain opening using digital image correlation. Due to the anisotropy of crystalline grains that will create residual stress during processing, polycrystalline materials deform and fracture in-homogeneously on a microstructural level.Digital image correlation has sufficient spatial resolution to measure intergranular crack propagation and the crack tip and the surface crack opening in alpha-alumina. The cracks tip are visualized by their stain map but they are not clear on the scanning electron microscopy and optical images, which can be used to measure crack length and surface crack opening displacement. The (SCOD) was calculated using DIC and the minimum SCOD was measured using DIC about 0.05µm at applied stress (30 Mpa).