Study on crack-inclusion interaction using digital gradient sensing method

The interaction between matrix crack and a round inclusion was studied by the method of digital gradient sensing. First, the stress fields at the matrix crack tip in the neighbor of a round inclusion were derived based on transformation toughening theory and Eshelby inclusion method, and the effect of the inclusion on the stress intensity factor of the matrix crack was analyzed. Then, the non-contact optical measurement system of digital gradient sensing was built up, and a three-point bending test was carried out using a single-edge cracked specimen. The mode I stress intensity factor was extracted from the angular deflection of the light rays. Finally, the effect of the inclusion on the angular deflection fields and the stress intensity factor at the crack tip was analyzed experimentally. These results will play an important role for evaluating the fracture mechanism of crack-inclusion interaction in composites.