Atomistic Simulations of Crack – Microstructure Interactions
Event details
| Date | 30.10.2013 |
| Hour | 13:15 › 14:15 |
| Speaker |
Prof. Dr.-Ing. Erik Bitzek, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany Bio: Erik Bitzek studied physics at the University of Stuttgart. After his dissertation at the Karlsruhe Institute of Technology he worked as postdoc at the Paul-Scherrer Institute in Switzerland and at the University of Pennsylvania, USA. Since 2011 he is assistant professor in Germany’s oldest and largest department for materials science and engineering at the Friedrich-Alexander-Universität Erlangen-Nürnberg. His research interest focuses on the properties of the elementary defects of the crystalline lattice, which he studies by atomistic simulation methods. The main objective thereby is to model how the organization and interaction of these defects influences the mechanical properties of materials. |
| Location | |
| Category | Conferences - Seminars |
Abstract : The interaction of cracks with constituents of the microstructure (e.g., dislocations, grain boundaries, particles or voids) is an important factor that determines the brittle or ductile behavior of a material. It is for example well known, that the interaction of pre-existing dislocations with the crack tip plays a crucial role in crack tip plasticity. The involved mechanisms remain however largely unclear. Here it is demonstrated by large-scale 3D atomistic simulations that individual pre-existing dislocations may lead to the generation of large numbers of dislocations at the crack tip. The simulations revealed fundamentally different interaction mechanisms for stationary cracks compared to propagating cracks. A detailed analysis of the dislocation – crack interactions allowed to determine which pre-existing dislocations lead to stimulated dislocation emission and multiplication processes and the slip systems they activate.
As an other example of crack – microstructure interaction we studied fracture along grain boundaries in a bi-crystal set-up. Here, asymmetrically oriented slip systems lead to different fracture behavior in opposing crystallographic propagation directions. The simulations show furthermore that even for perfectly brittle fracture, the fracture toughness can also depend on the crack propagation direction and can be significantly larger than the fracture toughness for brittle fracture in single crystals of the corresponding orientation. The results are discussed in terms of grain boundary trapping.
These examples of crack-microstructure interactions highlight the importance of including atomistic aspects in mesoscale fracture models.
As an other example of crack – microstructure interaction we studied fracture along grain boundaries in a bi-crystal set-up. Here, asymmetrically oriented slip systems lead to different fracture behavior in opposing crystallographic propagation directions. The simulations show furthermore that even for perfectly brittle fracture, the fracture toughness can also depend on the crack propagation direction and can be significantly larger than the fracture toughness for brittle fracture in single crystals of the corresponding orientation. The results are discussed in terms of grain boundary trapping.
These examples of crack-microstructure interactions highlight the importance of including atomistic aspects in mesoscale fracture models.
Practical information
- General public
- Free
Organizer
- IGM
Contact
- Géraldine Palaj