Study of the crack propagation characteristics of brittle materials at low temperatures based on 3D-ILC

In the field of cold zone engineering, temperature stress is frequently induced by a decrease in temperature, which leads to crack extension within the material. In order to study the expansion pattern of internal cracks under cooling conditions, we utilize the 3D internal laser-engraved crack technology to create internal cracks with varying heights and inclination angles inside the half-Brazilian disk specimen. Additionally, we perform a thermo-mechanical coupled 3D numerical simulation using the MTS criterion and the finite element method of thermal analysis. This simulation helps us obtain the stress intensity factors of crack expansion and visualize the expansion path of the cracks. The results show that prefabricated internal cracks produce 'U-shaped' cracks at an inclination angle of 0° and 'S-shaped' cracks at an inclination angle of 15°. Additionally, the extension of the non-inclined specimen crack is classified as a mixed type I–II crack, whereas the extension of the specimen with an inclined angle is classified as a mixed type I–II–III crack.