Modeling acoustic emission in the Brazilian test using moment tensor inversion

Abstract

Abstract To investigate the crack propagation and failure mechanisms of brittle materials in the Brazilian tests, an acoustic emission (AE) simulation was implemented in the Discrete Element Method. AE location and magnitude were monitored during the whole process of the simulation to detailedly observe crack initiation and associated AE evolution. Moment tensors were directly calculated by the forces and motions of the particles and decomposed into isotropic and deviatoric parts. According to the decomposition results of moment tensors, AE events (microcracks) can be classified into explosive (tensile), shear and implosive sources. Explosive sources were found to dominate both the total number and energy emission, followed by shear sources and finally implosive sources. AE distributions of different AE types were compared with the stress distribution to explore the relation between failure evolution and intrinsic stress state of the Brazilian test. Furthermore, the approach was applied to the compression test with a single flaw. Comparisons with experimental results indicated that the AE simulation can overcome the shortcoming of signal missing near the peak load in experiments and is approved to be an effective and accurate way to study rock fracture mechanism.