An Example of Realistic Modelling of Rock Dynamics Problems: FEM/DEM Simulation of Dynamic Brazilian Test on Barre Granite

The scope of this study is to numerically simulate the behaviour of Brazilian disc specimens as observed in laboratory during dynamic, high-strain rate, indirect tensile tests using an innovative combined finite-discrete element method (FEM/DEM) research code. Laboratory experiments using a split Hopkinson pressure bar (SHPB) apparatus were conducted by the authors and the measured indirect tensile strength values were used to verify the FEM/DEM models. In the models the applied boundary conditions, related to the loading rate of the specimen, were matched with the experimental observations. The results of the numerical simulations, including tensile strength and failure time, are in agreement with the laboratory findings. The main failure mechanisms, i.e. tensile splitting along loading axis and shear failure close to loading platens are captured by the numerical model. A linear relationship between tensile strength and loading rate is found for the range of dynamic strain rates tested and simulated. The simulation results are in good agreement with laboratory observations and demonstrate the potential for using FEM/DEM to realistically model dynamic response of rocks.

[1]  B. Mohanty,et al.  Experimental calibration of stress intensity factors of the ISRM suggested cracked chevron-notched Brazilian disc specimen used for determination of mode-I fracture toughness , 2006 .

[2]  C. A. Tang,et al.  Numerical simulation of Brazilian disk rock failure under static and dynamic loading , 2006 .

[3]  Antonio Munjiza,et al.  Combined single and smeared crack model in combined finite-discrete element analysis , 1999 .

[4]  Fangyun Lu,et al.  Determination of dynamic fracture parameters using a semi-circular bend technique in split Hopkinson pressure bar testing , 2009 .

[5]  C. Mariotti,et al.  Experimental and numerical study of concrete at high strain rates in tension , 2001 .

[6]  Per-Arne Lindqvist,et al.  Effects of loading rate on rock fracture: fracture characteristics and energy partitioning , 2000 .

[7]  M. Paterson Experimental Rock Deformation: The Brittle Field , 1978 .

[8]  B. Mohanty,et al.  Fracture toughness anisotropy in granitic rocks , 2008 .

[9]  A. Munjiza The Combined Finite-Discrete Element Method: Munjiza/Discrete Element Method , 2004 .

[10]  Peter K. Kaiser,et al.  A study on the dynamic behavior of the Meuse/Haute-Marne argillite , 2007 .

[11]  Jian Zhao,et al.  Experimental determination of dynamic tensile properties of a granite , 2000 .

[12]  Yang Wang,et al.  A finite element analysis for using Brazilian disk in split Hopkinson pressure bar to investigate dynamic fracture behavior of brittle polymer materials , 2006 .

[13]  Joseph W. Tedesco,et al.  Numerical analysis of high strain rate splitting-tensile tests , 1993 .

[14]  B. Mohanty,et al.  Effects of microstructures on dynamic compression of Barre granite , 2008 .

[15]  B. Mohanty,et al.  Fracture Toughness Measurements and Acoustic Emission Activity in Brittle Rocks , 2006 .

[16]  R. H. Evans,et al.  Microcracking and stress-strain curves for concrete in tension , 1968 .

[17]  Anna Pandolfi,et al.  Numerical investigation on the dynamic behavior of advanced ceramics , 2004 .

[18]  Sang-Ho Cho,et al.  Strain-rate dependency of the dynamic tensile strength of rock , 2003 .

[19]  O. K. Mahabadi,et al.  Y-GUI: A graphical user interface and pre-processor for the combined finite-discrete element code, Y2D, incorporating material heterogeneity , 2010, Comput. Geosci..

[20]  Francisco Gálvez,et al.  Tensile Strength Measurements of Ceramic Materials at High Rates of Strain , 1997 .

[21]  Hong Hao,et al.  Mesoscale modelling of concrete tensile failure mechanism at high strain rates , 2008 .

[22]  A. Munjiza,et al.  NBS contact detection algorithm for bodies of similar size , 1998 .

[23]  A. Munjiza The Combined Finite-Discrete Element Method , 2004 .