Key Engineering Materials Vols. 261-263

Abstract: This paper presents a new computer program called DIFAR (or dynamic incremental failure analysis of rock) that can simulate fracture process of brittle rocks under dynamic impacts. The program is based on a linear elastic finite element method incorporated with a failure criterion for damage checking. Modulus is reduced once the failure criterion is satisfied. In addition, Weibull distribution of the modulus and strength of the elements are used for modeling the mesoscopic heterogeneity. The failure criterion is a Mohr-Coulomb type of condition with a tensile cut-off, in which strength parameters are functions of the strain rate. More importantly, the whole fracture process of rock fragmentation can be simulated, including initiation, propagation, and coalescence of microcracks. The program DIFAR has been used to simulate elastic wave propagation and nonlinear fragmentation, and validity and efficiency of this program is demonstrated. The program can be considered as a dynamic counterpart of the RFPA, a failure analysis program for static loads, developed at Northeastern University, China.

Abstract: The writer has performed a series of dynamic breaking tests for researching impact of incidence direction of stress wave on rectangle plaster plank with cracks in its center and stress-strain relation’s variation and distribution on rectangle plaster plank with time under impacting action of stress wave, especially analyzing and testing breaking direction, developing route and sequence under the specific conditions of that incidence angles between cracks and stress wave are 0°, 30°, 45°, 60° and 90°.