On the determination of first-mode stress intensity factors and T-stress in a continuous functionally graded beam using digital image correlation method

In this study, fracture parameters of epoxy/glass functionally graded composite were determined experimentally using the digital image correlation (DIC) method. A functionally graded material (FGM) with continuous variation in elastic properties was manufactured by gravity casting in vertical template. A 30% volume fraction of glass spheres was dispersed in a low viscosity resin. A single edge crack specimen was examined in a three-point bending test under mode Ⅰ loading with cracks along the gradient tendency of the material properties. The mechanical properties of FGM were calculated according to ASTM D638. The DIC technique was adopted to obtain the deformation region around the crack tip. William's series was employed to calculate stress intensity factor and T-stress. The experimental results then verified by solving the FE model using ABAQUS program. The comparison between DIC and numerical results illustrated a largely acceptable achievement.