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Multiscale Modeling of Cohesive Crack Growth based on XFEM and Damage Model

Salahi Nezhad, Mohammad | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50379 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Khoei, Amir Reza
  7. Abstract:
  8. In this research, multi-scale modeling of mixed-mode failure mechanism of quassi-brittle materials is presented. For modeling a realistic crack growth in heterogeneious media, crack initiation criterion, crack growth orientation and the macroscopic cohesive law are derived from a microscopic sample. As a microscopic crack initiation criterion, acoustic tensor is investigated and scaled acoustic tensor has been proposed by comparison its results with maximum principal tensile stress. For crack growth direction based on micro-scale, acoustic tensor and multiscale aggregating discontinuities has been investigated and multiscale aggregating discontinuities by comparison results of these methods with damage contours. In multiscale model, cohesive macro-cracks are modeled using the extended finite element method (XFEM) and microscopic sample which exhibits diffusive damage. In numerical example, results of multiscale method based on microscopic criteria (scaled acoustic tensor as crack initiation criterion and multiscale aggregating discontinuities crack growth direction) has been compared with multiscale method based on macroscopic criteria (maximum principal tensile stress as crack initiation and crack growth direction criteria) in a mixed-mode example.The validity of the proposed method is shown by comparing the results against the direct numerical simulation (DNS) model
  9. Keywords:
  10. Multiscale Modeling ; Damage Model ; Extended Finite Element Method ; Cohesive Crack Propagation ; Mixed-Mode Fracture ; Direct Numerical Simulation (DNS)

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