Department of Engineering

PhD in: Discrete Dislocation Plasticity Analysis of Metal Fatigue

Principal Investigators:

• Vikram Deshpande in collaboration with
• Alan Needleman (Brown University, USA)
• Erik Van der Giessen (University of Groningen, The Netherlands)

Project Details:
Conventional descriptions of plastic deformation have found applications from the length scale of large structures to the length scale of grains in polycrystalline materials. With continued miniaturization the limit to the applicability of continuum descriptions is reached and fully atomistic, quasi-continuum and discrete dislocation descriptions are typically employed in material simulations, depending on the length scale of interest. In the discrete dislocation formulation, dislocations as carriers of plastic deformation are represented discretely but interatomic interactions are averaged out through elasticity thus making this technique ideally suited for computational modelling at the micron scale. This is a growing field of research internationally as it is expected to motivate simulation tools for the virtual testing of material.

The discrete dislocation framework has been successfully used to analyse Stage-II fatigue cracks in crystalline solids with fatigue, i.e. crack growth in cyclic loading at a driving force for which the crack remains stationary under monotonic loading, emerging as a natural outcome of the boundary value problem solution as a consequence of the evolution of internal stresses associated with the irreversibility of the dislocation motion.

The aim of this project will be to extend the framework to Stage-I cracks, i.e. mixed mode loading as a step towards understanding the initiation and growth of surface fatigue cracks. Further, the model will be extended to the polycrystalline case in order develop a more complete "engineering" simulation tool.

Background Required:
Continuum Mechanics, Fracture Mechanics, Plasticity.

Funding Source:
EPSRC studentship for UK students.

Research Groups Involved:

• Micromechanics

Application Deadline:
Open

For further information and to apply contact:

Informal inquiries via e-mail to Dr. V.S. Deshpande at vsd@eng.cam.ac.uk

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