The main aim of the project is the numerical study of fracture in anisotropic silicon using a dynamic phase-field fracture model.
Keywords: fracture, anisotropy, solar cells, finite element method, phase-field modeling
In the context of “green energy”, the inexhaustible nature of solar energy makes it a highly appealing source of electricity. Efficiency and life time of solar cells used in the photovoltaic industry highly depend on how they fracture. A large class of solar cell wafers are made of silicon, a material that exhibits fracture anisotropy whereby different energies are required for crack propagation along different directions. Hence, the fracture toughness (Gc) becomes orientation dependent, leading to preferential directions for crack propagation. Additionally, due to cubic symmetry of the material, the two weak directions are symmetrically, leading to zigzag crack patterns.
In phase-field modeling of fracture, the sharp crack is approximated by a continuous variable called the phase-field, thus removing the discontinuities in the displacement field due to the crack. In this project, the phase-field approach is used for the numerical analysis of fracture in silicon. Preliminary numerical results with the phase-field model to study anisotropic fracture in silicon have shown promising results.
In the context of “green energy”, the inexhaustible nature of solar energy makes it a highly appealing source of electricity. Efficiency and life time of solar cells used in the photovoltaic industry highly depend on how they fracture. A large class of solar cell wafers are made of silicon, a material that exhibits fracture anisotropy whereby different energies are required for crack propagation along different directions. Hence, the fracture toughness (Gc) becomes orientation dependent, leading to preferential directions for crack propagation. Additionally, due to cubic symmetry of the material, the two weak directions are symmetrically, leading to zigzag crack patterns.
In phase-field modeling of fracture, the sharp crack is approximated by a continuous variable called the phase-field, thus removing the discontinuities in the displacement field due to the crack. In this project, the phase-field approach is used for the numerical analysis of fracture in silicon. Preliminary numerical results with the phase-field model to study anisotropic fracture in silicon have shown promising results.
Planned tasks:
1. Literature study on fracture phenomenon in silicon and phase-field modeling of fracture.
2. Extension of an existing quasi-static phase-field framework in Matlab to the dynamic setting.
3. Verification of the implementation based on benchmark examples.
4. Numerical studies to simulate anisotropic fracture and zigzagging phenomenon.
5. Discussion of the results and documentation.
Inputs from the student will be considered and changes to the direction of the project may be accommodated.
Planned tasks:
1. Literature study on fracture phenomenon in silicon and phase-field modeling of fracture.
2. Extension of an existing quasi-static phase-field framework in Matlab to the dynamic setting.
3. Verification of the implementation based on benchmark examples.
4. Numerical studies to simulate anisotropic fracture and zigzagging phenomenon.
5. Discussion of the results and documentation.
Inputs from the student will be considered and changes to the direction of the project may be accommodated.
Highly motivated student with good knowledge in continuum mechanics, finite element methods, and good programming skills (in Matlab).
Sindhu Nagaraja
Computational Mechanics Group
Tannenstrasse 3, CLA J 17.2
Email: snagaraja@ethz.ch
Highly motivated student with good knowledge in continuum mechanics, finite element methods, and good programming skills (in Matlab).