CSENG Earth Sciences, Dept of
College of Science & Engineering
Twin Cities
Project Title: 
Shear Deformation of Geological Materials

This research largely focuses on deformation of geological materials. An important aspect of this research is deformation to very large strains, a task that this group is uniquely equipped to pursue. They make extensive use of deformation in a simple shear geometry and in a torsional configuration. The results from this research allow the researchers to explore the anisotropy in microstructure and the associated anisotropy in physical properties (strength, viscosity), which has direct relevance to understanding localization of deformation in shear zones such as the San Andreas fault.  

It has become clear that it is necessary to model the stress distribution in samples during deformation, particularly in the simple shear geometry. While the sample starts out completely confined between the two pistons, as deformation proceeds, parts of the sample move out from this confined geometry. As a result, the stress distribution evolves with time in a rather complex and poorly understood manner. As a result, some regions in the sample deform faster than others, and some regions effectively stop deforming. The resulting microstructure is highly heterogeneous. To interpret the microstructures, it is critical to determine the stress distribution and resulting spatial distribution of deformation rates. For this purpose, the researchers use COMSOL to run finite element models.

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