Simulation of Crack Nucleation in Materials with Regularly Arranged Spherical Pores Under Multiaxial Loading Conditions

Using the finite element method, a numerical investigation of the initial stage of crack propagation in a material containing spherical pores under multiaxial compression (constrained conditions) was carried out. The influence of the pore spacing and the mechanical properties of the material on fracture location and crack-propagation direction was analyzed for brittle and ductile materials. Material properties and the arrangement of defects were found to significantly influence the direction of crack propagation initiating on stress concentrators (structure defects), even in mutually perpendicular directions (for uniaxial compression). Numerical estimates were obtained for the characteristic sizes of the influence region of spherical pores on each other, beyond which the stress fields of the neighboring structural elements do not overlap. The dependence of the size of this influence region on the elastic characteristics of the matrix material was studied. The obtained results are important for numerically estimating the durations of the initial stages of the quasibrittle fracture of ceramic-based heterophase materials, particularly refractory materials.