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Modeling Shear Band Propagation in Saturated Porous Media Using eXtended Finite Element Method

Mikaeili, Ehsan | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48565 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Kazemi, Mohammad Taghi
  7. Abstract:
  8. Shear band is more relevant in porous medias rather than continuum media. Shear band is a narrow region of solid experiencing intense shearing. After initiation of shear band, the sliding on two sides of the band occurs. The area inside the shear band undergoes extreme plastic deformation, while experiences elastic unloading outside of the band. In porous materials, the direction of slip and discontinuity in displacement field is not same, as a result of dilation. In fact dilation requires an increase in the volume of the shear band zone. The main difficulty in modeling the shear band is that the width of shear band in contrast to the dimension of the media, is too small. Consequently, the width of the band corresponds to the element size in numerical solution, so as the mesh is refined the width of the band decreases. Also FEM shows a directional dependency that the direction is affected by the arrangement of the meshes. In this project, extended finite element method is exploited for the problem of strong tangential form shear band propagation. This method by adding the enrichment criteria to the standard finite element method, positions the discontinuity into the element. The enrichment function introduces an extra degrees of freedom in tangential direction to the discontinuity direction, that enables the element to freely deform along the discontinuity. Also the material nonlinearity of shear band zone, is captured by the Drucker-Prager plasticity model. Finally several numerical examples are presented to verify the efficiency of the model and theory presented for propagation of shear band in saturated porous media
  9. Keywords:
  10. Shear Band ; Extended Finite Element Method ; Saturated Porous Medium ; Strain Localization ; Strong Discontinuity ; Weak Discontinuity

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