PhD scholarship in Residual Stress Measurement and Design of Advanced Metal Microstructures

DTU Mechanical Eng
Tuesday 09 Oct 18

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DTU, Department of Mechanical Engineering, the section for Manufacturing Engineering has a vacant 3-year PhD position in the recently granted project by Danmarks Frie Forskningsfond (DFF). The position is to be filled January 1st 2019 or soon after that.

Residual stresses develop locally in materials during manufacturing and service, and are crucial for the mechanical and physical properties including strength, ductility and fatigue lifetime. To optimize the materials performance and to design advanced materials, it is therefore essential to determine non-destructively the local residual stresses and relate them to the local materials inhomogeneities in 3D. So far, such measurements are rare and can only be done at large international synchrotron facilities. In the new DFF project, a new laboratory based X-ray diffraction technique, LabXRS, will be developed, which will be a game-changer enabling many more scientists to perform sufficient numbers of local RS measurements.

This project aims at using mainly this new technique supplemented by synchrotron techniques to quantify for the first time systematically the level of local residual stresses and to investigate their influence on the mechanical properties of multiphase materials.

The aims of the project are to: 

  • Characterize the level and distribution local residual stress in different phases in metals after different thermo-mechanical processing, and relate the stress to the local microstructures
  • Develop a new crystal plasticity finite element model to predict the residual stress and to investigate its effects on the plastic deformation and mechanical properties
  • Design advanced metals with superior mechanical properties by tailoring the microstructure and local residual stresses.

Responsibilities and tasks
To achieve the goals, advanced 3D/4D laboratory and synchrotron x-ray techniques will be used to quantify the microstructure and local residual stress of metals after different thermo-mechanical processing. The PhD will plan and conduct experiments and analyze the results. Advanced crystal plasticity finite element modeling will be developed incorporating real 3D microstructures and stress states. This will be in corporation with an external partner in France. The candidate will work in close collaboration with a group of senior scientists, technicians as well as Post Docs and PhDs and with the Danish Company Xnovo Technology ApS.

Some of the research questions this project will address are: 

  • What is the magnitude and distribution of the local residual stress within different phase of the metal?
  • How does the stress build up?
  • How does annealing affect stress relaxation?
  • What is the relation between the local residual stress and microstructure parameters, e.g. texture and grain size?
  • How does the local residual stress affect the local plastic deformation during tensile and fatigue tests, and thus the mechanical properties of the material?

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.

Experience within one or more the following topics are an advantage: 

  • Materials characterization
  • Numerical modeling
  • X-ray diffraction
  • Materials mechanics
  • Experiments in the laboratory.

Good communication skills in English, both written and spoken, are essential. You should also have the ability to work independently, to plan and carry out complicated tasks.

Approval and Enrolment
The scholarship for the PhD degree is subject to academic approval, and the candidate will be enrolled in one of the general degree programmes at DTU. For information about our enrolment requirements and the general planning of the PhD study programme, please see the DTU PhD Guide.   

We offer
DTU is a leading technical university globally recognized for the excellence of its research, education, innovation and scientific advice. We offer a rewarding and challenging job in an international environment. We strive for academic excellence in an environment characterized by collegial respect and academic freedom tempered by responsibility.

Salary and appointment terms
The appointment will be based on the collective agreement with the Danish Confederation of Professional Associations. The allowance will be agreed upon with the relevant union. The period of employment is 3 years. 

The work will be carried out half at DTU Lyngby Campus and half at DTU Risø Campus.

You can read more about career paths at DTU here.   

Further information
Further information may be obtained from Senior Researcher Yubin Zhang, e-mail: yubz@mek.dtu.dk.  

You can read more about Department of Mechanical Engineering at www.mek.dtu.dk.  

Application
Please submit your online application no later than 18 November 2018 (local time, before midnight). Applications must be submitted as one PDF file containing all materials to be given consideration. To apply, please open the link "Apply online", fill out the online application form, and attach all your materials in English in one PDF file. The file must include: 

  • A letter motivating the application (cover letter)
  • Curriculum vitae
  • Grade transcripts and BSc/MSc diploma
  • Excel sheet with translation of grades to the Danish grading system (see guidelines and Excel spreadsheet here)

Candidates may apply prior to obtaining their master's degree but cannot begin before having received it.

All interested candidates irrespective of age, gender, race, disability, religion or ethnic background are encouraged to apply.

DTU Mechanical Engineering covers the fundamental engineering disciplines within Solid mechanics, Fluid mechanics, Coastal and Maritime Engineering, Energy systems and energy conversion, Materials and Surface Engineering, Manufacturing Engineering, Engineering design and Product development. The department has a scientific staff of about 150 persons, 95 PhD students and a technical/administrative support staff of about 80 persons.

DTU is a technical university providing internationally leading research, education, innovation and scientific advice. Our staff of 6,000 advance science and technology to create innovative solutions that meet the demands of society, and our 11,200 students are being educated to address the technological challenges of the future. DTU is an independent academic university collaborating globally with business, industry, government and public agencies.