Abstract：The effects of mixed stress on glass specimen with an inclined straight-through crack were investigated by means of FEM and failure simulation. The simulation results of crack initiation and fractures for various inclined cracks and the figures of calculated KIC，KIIC corresponding to different crack angles in glass samples were obtained. It demonstrated that three types of stresses existed in the crack's tip：mode I stress intensity factor，mode II stress intensity factor，and the stress parallel to the crack. It was disclosed that，for brittle materials in plane stress state，mode II stress intensity and parallel stress have a considerable influence on the crack growth. Mode I stress intensity is the dominating factor，and mode II stress intensity is subordinate but the tensile stress parallel to the crack plays a role in the crack arrest. This result is different from the traditional concept that the fracture of the brittle materials like glasses and ceramics is determined by mode I stress intensity alone.
