Study of intercrystalline facture stress intensity factor of multicrystalline rock under mesomechanics

摘要

Abundant macroscopic experimental studies reveal that the multicrystalline material failure is mainly caused by inter-crystalline fracture which occurs along the boundaries of crystalline grains of the rocks.The propagation of the cracks along the kink grain boundaries constitutes the form of winged crack propagation among different materials.At present,there are many methods to calculate the winged cracks and most results are obtained based on equivalent method under the condition of homogeneous medium.In this paper the computational process was established using ANSYS Parametric Design Language and the winged crack tip stress intensity factor at the interface of the intercrystalline fracture via was obtained using the numerical extrapolation method for the nodes displacement.Then a comparison is made with the HN approximate calculation model and differences of crack propagation between the heterogeneous brittle material and the homogeneous material are analyzed and also,the influence exerted by the geometrical characteristics of the crystalline grain and the heterogeneity degree (Dundurs parameter) of the material on the crack propagation are studied.The result takes the multicrystallinity and heterogeneity of the rocks into consideration and reveals the change of the stress intensity factor when the intercrystalline crack extends in the rock.