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Research Abstracts Online
January 2009 - March 2010

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University of Minnesota Twin Cities
Institute of Technology
Department of Civil Engineering

PI: Andrew Drescher, Associate Fellow

Modeling Processes Involving Soil-Object Interaction

These researchers are simulating processes involving an object moving through geomaterials like soil and rock using ABAQUS, considering the large, plastic deformations that result when significant object penetration occurs. General interests in such geomechanical processes are the instabilities occurring, the question of whether a steady-state (or periodic) configuration exists, and essential differences between three-dimensional and two-dimensional analysis. The analyses are used to investigate the effects of material type (using various constitutive models), material layering, object type and geometry, loading on the object, and friction at the soil-object interface. The potential for analytic or semi-analytic methods for modeling soil-object interaction are evaluated based on the results.

Emphasis in recent work has been on studying the differences arising between three-dimensional and two-dimensional (plane strain) analyses of a wheel on cohesive material. This work has revealed that three-dimensional and two-dimensional models provide similar predictions of dynamic quantities such as horizontal wheel force, whereas kinematic quantities such as wheel penetration can be drastically different. Effort was also made to simulate purely frictional (granular) materials. It was found that a classical Mohr-Coulomb-type yield function with nonassociated plastic flow leads to severe numerical instabilities for a rolling wheel. Future work using MSI resources includes implementing other constitutive models in the simulations. Models for frictional soils leading to numerical stability and models allowing for compaction (i.e., cap plasticity model) are of particular interest.

Group Member

James P. Hambleton, Graduate Student