ABSTRACT:

This work presents a new approach in simulation of rock blasting process by coupling the Finite Element Method (FEM) and the Smooth Particle Hydrodynamics (SPH) method. The rock is initially modelled with FEM whereas the explosive is modeled with SPH. Interaction is achieved by including the elements near the rock-gas interface in the neighbor list of SPH system and applying the calculated traction to element sides. Further, highly distorted rock elements are automatically converted to particles and linked to the FEM system on the fly. A patch test is demonstrated to check the validity of the proposed technology.

1 INTRODUCTION

Simulating the phenomenon of blasting of rocks, which involve high strain rates using the Finite Element Method (FEM), becomes difficult as FEM suffers from mesh tangling. Corrections such as mesh rezoning, element erosion etc. to do away with badly distorted elements must be employed. This increases the computational time. Mesh-less methods such as the Smooth Particle Hydrodynamics (SPH) method by Lucy (1977) and Monaghan & Glingold (1983) can handle large distortions inherently but it is more computationally expensive than FEM. It also suffers from certain potent instabilities when applied to problems of deforming solids. Moreover, applications of boundary conditions in SPH is tedious. Coupling the FEM and the SPH method could be more efficient in such problems, where regions of high strain rates and large deformations are modelled with SPH particles to capture deformations and the remaining regions are modelled with FEM to save computational time and seamlessly apply boundary conditions. This work adopts with suitable modifications the algorithm proposed by Xiao et al. (2011) that treat elements near the coupling interface as imaginary particles to calculate forces on particles from adjacent elements and impose equivalent tractions on element edges on the coupling interface in accordance with the particle stress associated with that element. In this work, since rock basting is a fluid-solid interaction problem the expanding gas of the decomposing explosive is exclusively modeled with SPH particles. The rock is modelled with FEM under suitable boundary conditions and the severely distorted rock elements are changed to SPH particle during the course of computation.

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