A Concurrent Multiscale Modelling of Crack Propagation with the Use of Extended Finite Element Method

Alizadeh, Omid | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45524 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): khoei, Amir Reza
  7. Abstract:
  8. Crack propagation problem is one of the most important problems that are being investigated for a long time. Plenty of various approaches have been utilized to simulate the crack propagation phenomenon. Continuum based methods like Finite element (FE), Extended Finite element (XFEM), have been successfully applied, and the obtained results are valid in macro scale. However, the stress filed near crack tip in FEM modeling of crack, is not exquisite enough due to inability of continuum based approaches in revealing atomistic aspects of the material.
    In order to gather efficiency of the continuum based domain and the accuracy of the atomistic based domain, Multiscale methods are employed. In these thesis a concurrent multisacale technique is utilized. In multiscale modelling, the atomistic region is made in suitable size not greater than the modelling demand in order to decrease the number of degrees of freedom. In current multiscale modelling, as the crack propagates, the crack tip moves outside of the atomic region and enters in the continuum part in which the accuracy falls down. In this research a new method has been introduced to move the atomistic region as the crack tip moves. This technique ensures the accuracy of the computations. This technique emphasizes on the procedure of converting continuum part to atomistic and vice versa.

  9. Keywords:
  10. Concurrent Multi-scale Model ; Crack ; Molecular Dynamics ; Extended Finite Element Method

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