Study on the effect of inclusion shape on crack-inclusion interaction using digital gradient sensing method

Abstract

The effect of inclusion shape on the mode I stress intensity factor of the matrix crack interaction with a rigid inclusion was studied experimentally using digital gradient sensing (DGS) method. First, the noncontact optical measurement system of DGS was built up, and the specimens with different shapes of inclusion ahead of matrix crack were performed using transparent epoxy resin. Then, the angular deflection contour at the crack tip with different shapes of inclusions was obtained, and the stress intensity factors were extracted from the stress gradient filed based on least square fitting. Finally, a numerical simulation was conducted on the same problem using ABAQUS, and the stress intensity factors computed from FEM were compared with the experimental results. The results show that the stress intensity factors extracted from the stress gradient filed are agreed well with the numerical and theoretical results.

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 ].…”