Events Calendar

Oral Dissertation Defense

Speaker: Sara Abedi, CEE Ph.D, Candidate

Talk Title: Meso- Scale Kinemetics in Shear Bands and Impact of Material Heterogeneity on Shear Band Development in Sand

Abstract:
This study aims to improve our understanding of strain localization in sands from the meso-scale perspective. First, this research contributes to characterizing and quantifying experimentally the micro- and meso-scale kinematic mechanisms associated with force chains and vortex structures in shear bands in real granular materials. The Digital Image Correlation (DIC) technique is used to obtain the two-dimensional, incremental surface displacements from digital images of deforming plane strain sand specimens. The aim herein is to use DIC results as a means to 1) evaluate meso-scale kinematic behavior inside shear bands through the course of large deformation, 2) infer the kinematic manifestation of force chains and vortex-structures and study their evolution and dissolution in sheared sands, and 3) conduct a preliminary investigation of length scales in granular shear. Second, we studied the physical mechanism underlying shear band formation in a supposedly uniform soil specimen, apart from the boundary influences or loading non-uniformities. The technique of X-Ray Compute Tomography (CT) is used to capture meso-scale density variations in plane strain specimens of sand. Digital image processing techniques are then used to transfer the CT results as input to the three-dimensional FE models. Finally, Digital Image Correlation (DIC) enables tracking of the in plane displacement of the sand specimen throughout plane strain compression tests performed on the CT specimens. The laboratory results are then compared with numerical predictions. This direct comparison should enable refinement in numerical models to achieve better predictability.

Adviser: Dr. Amy Rechenmacher

Location: Kaprielian Hall (KAP) - 209 Conference Room

Audiences: Everyone Is Invited

Contact: Evangeline Reyes