Two PhD scholarships are available at DTU Mechanical Engineering, Section for Solid Mechanics, in the field of fatigue and wear in rolling and sliding contacts. One has focus on computational stress and damage modeling, while the other has focus on elastohydrodynamic lubricant film modelling and experimental verification. The department has well-established research activities in these fields and the present two scholarships are partly funded by the Danish Centre for Knowledge based Engineering for Improved Reliability of Critical Wind turbine Components (REWIND) supported by the Danish Agency for Science, Technology and Innovation.
Project descriptions
Wind turbines are huge structures that are subjected to highly dynamic loads arising from the complex interplay between the varying wind field and wake from other turbines, the rotation of the rotor as well as the transmission and the electric generator in the drivetrain inside the nacelle. An important consequence of this is that most components in a wind turbine are experiencing highly dynamic loads resulting in wear or fatigue of the components.
Computational stress and damage modeling project: The aim of this project is to analyze the influence of stress field variations with the cyclic loading, for different possible materials and for different surface treatments, and to use methods of plasticity and damage mechanics in combination with micro-mechanics modeling. The onset of cracks may take place at inhomogenities in the material, which results in the fatigue cracks starting as sub-surface cracks that grow towards the surface. Inclusions in the material may cause local stress concentrations affected by the local changes in material properties. Continuum damage mechanics will be applied in the development of models describing the initiation and evolution of fatigue cracks.
The following topics have been identified as the most important:
- Finite Element modeling
- Damage mechanics
- Fatigue models
- Plasticity
Elastohydrodynamic lubricant film modeling and experimental verification project: The pressure distribution in the contact between the rolling and sliding elastic elements is described through an elasto-hydrodynamic lubrication model. It is the aim of this part of the project to analyze the influence of properties of the involved components such as lubricant properties, elastic solids geometry and material properties, surface roughness and texture, etc. on the pressure distribution in the contact.
The aim of the experimental part is to verify the theoretical findings in the elastohydrodynamic part of this project combined with the above stress field modeling project. The experimental part will involve development of suitable equipment for the testing and verification as well as the instrumentation, testing and verification itself.
The following topics have been identified as the most important:
- Finite Element Modeling
- Tribology
- Mechanical testing
- Experimental data acquisition
For both projects the expected starting date is 1st August 2011.
Qualifications
Candidates should have a master's degree in engineering or a similar degree with an academic level equivalent to the master's degree in engineering. Strong skills in Solid Mechanics and Finite Element programming in Fortran are required. Furthermore, fluency in speaking, reading and writing English is needed. For the second project, involving experimental work, it is further required that the candidate has a strong interest in testing and instrumentation. Candidates with experience in LabView programming will be preferred.
To apply, please read the full job advertisement at www.dtu.dk/vacancy
Application deadline: 15th April 2011.