Study on crack-inclusion interaction using digital gradient sensing method

Abstract

The interaction between matrix crack and a round inclusion was studied by the method of digital gradient sensing (DGS). 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 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 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.

Enhanced Digital Gradient Sensing Using Backlight Digital Speckle Target

“…DGS can be classified as transmission-mode DGS (t-DGS) and reflection-mode DGS (r-DGS), where the former one measures non-uniform stress distribution induced angular deflections to characterize stress gradient fields of transparent materials, while the later one measures angular deflections reflected off an optically reflective surface to estimate the surface slopes of specular structures [ 1 , 2 ]. Due to its advantages of simple implementation, high accuracy, and high computational efficiency [ 3 , 4 , 5 ], DGS has been successfully applied in many fields—e.g., material testing, fracture mechanics, impact dynamics, and high-temperature characterizations—showing great potential in recent studies [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ].…”