Exploration of Discrete Element Method to Dynamically Model Sandy Terrain 2010-01-0375

This research examines a Discrete Element Method (DEM) for modeling the behavior of sand under various loading conditions as a critical first step in developing computational tools to aid in designing new sand-tire interaction systems for improved traction and mobility. Sand as a material is challenging to model computationally due to its unusual behavior: sometimes resembling a fluid and sometimes behaving more like a solid, yet never exactly replicating either. This behavior arises from the particulate nature of sand which, in contrast to the systems typically modeled in continuum mechanics, is not readily represented by continuum models. In sand, elements (i.e. particles) do not have permanent associations with neighboring elements as they do in most continua, but rather are free to migrate anywhere in the domain according to their interactions with other elements. Discrete Element Methods are numerical techniques designed to model the dynamics of particulate systems and are being used to develop an understanding of the behavior of certain sand systems. The number and the complexity of particles in a DEM simulation are limited by computational resources. Therefore, to realistically approximate large systems of complex particles, such as a real sand-tire system, the parameters of the simplified particles in a DEM system must be calibrated experimentally. Once this has been performed, it is anticipated that DEM simulations will provide benchmarks for validating new continuum models to be implemented in continuum codes, such as the Finite Element Method (FEM) or the Meshless Integral Method (MIM), which typically require less computational effort. Subsequent to validation, coupling of computational methods may be achieved in order to exploit the strengths of both DEM codes (accuracy in handling extreme deformations) and continuum codes (computational efficiency). This paper introduces the capabilities of DEM toward modeling the behavior of sand as it interacts with various loading conditions, and provides preliminary results of some relationships between DEM parameters and material properties of sand.