Brown University School of Engineering

Joint Materials/Solid Mechanics Seminar Series: “Two-scale modeling of shear bands in fluid infiltrating solids”

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Monday, February 03, 2014 4:00pm - 5:00pm

WaiChing Sun: Assistant Professor, Department of Civil Engineering and Engineering Mechanics, The Fu Foundation School of Engineering and Applied Science, Columbia University,. Many man-made and natural geological processes may lead to the inceptions and propagations of narrow zones in which significant inelastic deformation concentrates. Examples include shear bands, compaction bands, fractures and joints. Due to the difference in spatial scales between the thickness of the localized zone and the rest of the deformable body, these localized diffusion-deformation processes can be approximated as a strong discontinuous displacement field across interfaces. Depending on how microstructural attributes (e.g. porosity, tortuosity and pore size distribution) evolve, these localized zones may become flow barriers or conduits [1]. The objective of this study is to derive and implement computer models that capture the post-bifurcated localized responses of shear band formed in fluid infiltrating solids. Our continuum formulation features an equal-order finite element in which tri-linear element is used to discrete both the displacement and pore pressure [2,3]. By introducing a projection-based stabilization technique, the model is capable of producing stable solution with arbitrary time step size and drainage conditions. Meanwhile, the fully coupled diffusion-deformation mechanism of the localized zone is captured by a multi-physical variational localization element that admits displacement and pore pressure jumps. Numerical examples simulated with various constitutive laws are provided to demonstrate the robustness and versatility of the proposed models. Challenges on modeling shear bands in geomaterials will be discussed.