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Discrete Element Analysis
Rory O'Connor and Nabha Rege Intelligent Engineering Systems Laboratory (IESL) |
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INVITED PAPER |
ABSTRACT
This paper describes recent developments in the grain by grain modeling of granular materials using the discrete element method. The core components of a discrete element system are detailed including contact detection, contact force generation, dynamic solution and time integration, and rigid and deformable body motion. The major problem in developing a robust computational laboratory for testing materials is identified as finding algorithms which scale well as the number and complexity of the discrete bodies increases. This scaling problem is illustrated in detail for the contact detection problem. An algorithm based on a discrete functional representation of the object geometry is proposed and is shown to scale as O(N) both with the number of bodies and with the geometric complexity o f each body. A method of coupling discrete and finite elements for deformable bodies is described and applied to contact between bodies. Finally, a prototype computational laboratory is applied to the investigation of granular deformations. Results are described which reveal the formation and interaction of granular vortices as a fundamental mechanism in deforming granular materials. The vortices are observed at all strains, are coherent over time and appear to play an important role in all granular deformations including the formation of shear bands.
KEYWORDS: DEM, discrete elements, FEM, finite elements, modeling, analysis, particles, soil mechanics, granular materials, deformation, stress, strain
