Micromechanical finite element modeling of compressive fracture in confined alumina ceramic

A two-dimensional finite element model is developed to investigate intergranular fracture in alumina under compression. The grain interiors are modeled as anisotropic elastic and the properties of the grain boundaries are fitted from experimental data. Material failure is found to occur by the linking of wing cracks. The effect of confinement pressure on the strength and strain to failure is investigated. Confinement pressure is shown to have a weak effect on the total fracture surface at failure, but is found to have a strong effect on microcrack coalescence. The numerical model suggests that the size of the largest microcrack cluster or the variance of microcrack length could be a useful criterion for predicting impending catastrophic failure.