Fracture of β-SiC bulk with a void of different shapes under different loading modes

Molecular dynamics simulations using the Tersoff potential are performed to explore the mechanical properties of β-SiC bulk with a void of elliptic and circular shapes under different loading conditions. For a given void volume fraction, the geometric properties of elliptic and circular voids are differentiated by their aspect ratios. We find that, the critical stress related to the material failure under simple shear is the largest for the circular void whereas smaller for the elliptic void. Moreover, elliptic void rotates during the shear. Further analysis by comparing the critical stresses under uniaxial tension and deformation reveals that the presence of tensile stress in the direction perpendicular to the stretching direction has little impact on the final fracture stress. Finally, it is shown that the fracture-stress surfaces of voided β-SiC bulk for a specified void aspect ratio is in the rectangular shape. For a given void volume fraction, vertexes of fracture-stress surfaces for different void aspect ratios constitute a linear relationship between stresses in two directions. This study may help us understand and reveal the underlying atomistic deformation mechanisms of void geometry-dependent mechanical properties of β-SiC bulk.