PhD Fellowship in Mechanical Engineering: Experimental and Numerical investigation of welding

University of Stavanger
December 18, 2022
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PhD Fellowship in Mechanical Engineering: Experimental and Numerical

investigation of welding

Job description

The University of Stavanger invites applicants for a PhD Fellowship in Mechanical Engineering at the Faculty of Science and Technology, Department of Mechanical and Structural Engineering and Material Science. The position is vacant from January 2023.

This is a trainee position that will give promising researchers an opportunity for academic development through a PhD education leading to a doctoral degree.

The hired candidate will be admitted to the PhD program in Science and Technology. The education includes relevant courses amounting to about six months of study, a dissertation based on independent research, participation in national and international research environments, relevant academic communication, a trial lecture and public defence. Read more about the PhD education at UiS on our website.

The appointment is for three years with research duties exclusively.

Research topic

The PhD Fellow will be affiliated with the following project: “Investigation of mechanical, thermodynamical, material flow in weld pool, and metallographic properties in multi-pass proximity welds”.

Highly localized transient heat input in fusion welding processes (e.g., arc welding) generates considerable residual stresses (welding residual stress) and deformations (welding distortion, welding shrinkage, welding warpage) during and after the welding process, that can greatly impair structural and mechanical integrity of the welded joint. This is further exacerbated by the unavoidable proximity welds in fabrication due to as-designed geometrical configurations and lack of guidelines (with technical justifications) in existing welding codes and standards. Welding residual stresses increase the potential risk of brittle fractures in welded joints as tensile residual stresses reduce fatigue strength and corrosion resistance, whilst compressive residual stresses diminish the stability limit. Although multi-pass welding simulation models have been evolved demonstrating reasonable thermal and mechanical response, when the thermal models are compared with experimental data, they yield less accurate results for residual stresses. Improving the accuracy of thermal modelling is essential to enhance the accuracy of the mechanical model, to enable the mechanical model to capture the elastic- plastic behaviour (i.e., considering both the weld and base materials) by taking the effect due to phase transformations and material flow in the weld pool into consideration. In this context, it is vital to investigate welding microstructure evolution and performance from composition, thermal cycle, microstructure, mechanical properties, weldability and service performance perspectives to enable improved numerical modelling accuracy.

A wide range of simulation models are available to predict the residual stress distribution in weld joints. However, the inability to adequately account for the effects of weld pool flow for computing the stress filed associated with the weld joints is one of the key limitations of such models. The fluid flow within the weld pool significantly controls the heat and mass transport in the rapid solid-liquid-solid phase change during the welding processes. The heat flow and the evolving temperature field is the most crucial factor for inducing thermal residual stresses. Recent in situ experiments indicate how the weld pool flow behaves under different physical aspects, which are directly connected to welding techniques, process parameters and material composition. Therefore, incorporating weld pool flow phenomena into the stress model will allow accurate prediction of residual stresses through realistic physical considerations. In addition, having weld pool flow within the model allows integrating other flow driven defects, such as segregation, undercuts, humping and pores into the residual stress prediction model. This will be a significant step towards the development of comprehensive resilient nature of a given weld joint. The proposed model will be based on standard software packages (i.e., Abaqus or ANSYS) with supplemental models implemented by the candidate. At the latter part of the project, to validate the model, samples will be fabricated at the university lab (and/or industrial partner) and residual stress measurements will be carried out using neutron diffraction at PSI, Switzerland (and/or other potential facilities) and/or X-ray diffraction (XRD) facility in SINTEF. The microstructure of the weld will be analysed using optical and electron microscopy facilities to analyse the segregation and cracks, etc. Additionally, provisions for X-ray tomography will be kept studying finer cracks etc at the fusion zone (solidified melt pool) in 3 dimensions to compare with model predictions.

This PhD project is focused on the integration of numerical simulation capabilities with the support of experimental investigations to enable accurate predication of structural and mechanical integrity of proximity welds. The study also aims for a deeper insight and understanding of the fatigue behaviour in proximity welds and risk of potential damage under cyclic loading.

Project proposal

As an applicant, you must prepare a preliminary project proposal for a doctoral project within the subject area, which explains the problem, relevance, theoretical and methodological approach. Your preliminary project proposal will be included in the application assessment.

During the first three months of the employment period, the project proposal and progress plan will be further developed in cooperation with your supervisors and completed for the final plan for the PhD-project. A project proposal template can be found here.

Qualification requirements

We are looking for applicants with a strong academic background who have completed a five-year master degree (3+2) within mechanical engineering, manufacturing engineering, materials engineering or related disciplines, preferably acquired recently; or who possess corresponding qualifications that could provide a basis for successfully completing a doctorate.

It will be an advantage if you have:

  • laboratory testing experiences: the use of fatigue, tensile, etc., testing facilities for the testing of mechanical properties and material characterization (microstructure) analysis.
  • familiar with FEM software (e.g. ANSYS/Abaqus) and CFD modelling (e.g., OpenFOAM).
  • experience with scientific programming, in e.g., Fortran,Python, C++ etc.
  • background in X-ray diffraction (XRD), neutron scattering, X-ray tomography, and analysis of data
  • To be eligible for admission to the doctoral programmes at the University of Stavanger both the grade for your master's thesis and the weighted average grade of your master's degree must individually be equivalent to or better than a B grade. If you finish your education (masters degree) in the fall 2022 you are also welcome to apply.

    Applicants with an education from an institution with a different grade scale than A-F, and/or with other types of credits than sp/ECTS, must attach a confirmed conversion scale that shows how the grades can be compared with the Norwegian A-F scale and a Diploma Supplement or similar that explains the scope of the subjects that are included in the education. You can use these conversion scales to calculate your points for admission.

    Emphasis is also placed on your:

  • motivation and potential for research within the field
  • professional and personal skills for completing the doctoral degree within the timeframe
  • ability to work independently and in a team, be innovative and creative
  • ability to work structured and handle a heavy workload
  • having a good command of both oral and written English
  • Requirements for competence in English

    A good proficiency in English is required for anyone attending the PhD program. International applicants must document this by taking one of the following tests with the following results:

  • TOEFL – Test of English as a Foreign Language, Internet-Based Test (IBT). Minimum result: 90
  • IELTS – International English Language Testing Service. Minimum result: 6.5
  • Certificate in Advanced English (CAE) or Certificate of Proficiency in English (CPE) from the University of Cambridge
  • PTE Academic – Pearson Test of English Academic. Minimum result: 62
  • The following applicants are exempt from the above requirements:

  • Applicants with one year of completed university studies in Australia, Canada, Ireland, New Zealand, United Kingdom, USA
  • Applicants with an International Baccalaureate (IB) diploma
  • Applicants with a completed bachelor's and / or master's degrees taught in English in a EU/EEA country
  • We offer
  • a PhD education in a large, exciting and societally important organisation
  • an ambitious work community which is developing rapidly. We strive to include employees at all levels in strategic decisions and promote an informal atmosphere with a flat organisational structure.
  • colleague-based guidance programme (NyTi) if teaching is a part of your position
  • salary in accordance with the State Salary Scale, l.pl 17.515, code 1017, NOK 501 200 gross per year with salary development according to seniority in the position. A higher salary may be considered in special cases. From the salary, 2% is deducted as a contribution to the Norwegian Public Service Pension Fund.
  • automatic membership in the Norwegian Public Service Pension Fund, which provides favourable insurance- and retirement benefits
  • favourable membership terms at a gym and at the SIS sports club at campus
  • employment with an Inclusive Workplace organisation which is committed to reducing sick leave, increasing the proportion of employees with reduced working capacity, and increasing the number of professionally active seniors
  • "Hjem-jobb-hjem" discounted public transport to and from work
  • as an employee in Norway, you will have access to an optimal health service, as well as good pensions, generous maternity/paternity leave, and a competitive salary. Nursery places are guaranteed and reasonably priced
  • relocation programme
  • language courses: On this page you can see which language courses you may be entitled to (look up “language courses” under employment conditions)
  • Diversity

    University of Stavanger values independence, involvement and innovation. Diversity is respected and considered a resource in our work and learning environment. Universal design characterises physical and digital learning environments, and we strive to provide reasonable adjustments for employees with disabilities.

    You are encouraged to apply regardless of gender, disability or cultural background.

    The university aims to recruit more women within the subject area. If several applicants are considered to have equal qualifications, female applicants will be given priority.

    Contact information

    More information on the position and project description can be obtained from Professor R.M. Chandima Ratnayake, tel: +47 51 83 19 38, e-mail: chandima.ratnayake@uis.no and Associate Professor Knut Erik Teigen Giljarhus tel: +47 99 26 54 74, e-mail: knut.e.giljarhus@uis.no.

    Information about the appointment procedure can be obtained from HR advisor Rosa Andrade, tel: +47 51 83 11 91 e-mail: rekruttering@uis.no.

    Application

    To apply for this position please follow the link "Apply for this job". Your application letter, relevant education and work experience as well as language skills must be registered here.

    The following documents must be uploaded as attachments to your application:

  • cover letter explaining your interest in the project and the relevance of your background and experience to the position.
  • project proposal, a project proposal template can be found here.
  • CV with a full summary of your education and experience
  • references, certificates/diplomas and other documentation that you consider relevant
  • Diploma Supplement or similar and a confirmed conversion scale if this is required
  • documentation on competence in English if this is required
  • publications or other relevant research work
  • Applications are evaluated based on the information available in Jobbnorge at the application deadline. You should ensure that your application shows clearly how your skills and experience meet the criteria which are set out above and that you have attached the necessary documentation.

    The documentation must be available in either a Scandinavian language or in English. If the total size of the attachments exceeds 30 MB, they must be compressed before upload.

    Please note that information on applicants may be published even if the applicant has requested not to be included in the official list of applicants - see Section 25 of the Freedom of Information Act. If your request is not granted, you will be notified.

    UiS only considers applications and attachments registered in Jobbnorge.

    General information

    The engagement is to be made in accordance with the regulations in force concerning State Employees and Civil Servants, and the acts relating to Control of the Export of Strategic Goods, Services and Technology. If your application is considered to be in conflict with the criteria in the latter legislation, it will be rejected without further assessment.

    Employment as PhD Fellow is regulated in "Regulations concerning terms and conditions of employment for the posts of post-doctoral research fellow and research fellow, research assistant and resident".

    Your qualifications for the position, based on documentation registered in Jobbnorge, will be assessed by an internal expert committee. Based on the committee's statement, relevant applicants will be invited to an interview before any recommendations are made. References will also be obtained for relevant candidates. More about the hiring process on our website.

    The appointee will be based at the University of Stavanger, with the exception of a stay abroad at a relevant centre of research.

    It is a prerequisite that you have a residence which enables you to be present at/available to the academic community during ordinary working hours.

    The position has been announced in both Norwegian and English. In the case of differences of meaning between the texts, the English text takes precedence.

    UiS - challenge the well-known and explore the unknown

    The University of Stavanger (UiS) has about 12,000 students and 2,200 employees. The university has high ambitions. We strive to have an innovative and international profile, and be a driving force in knowledge development and in the process of societal change. Our common direction is driven by consideration for green and sustainable change and equitable social development, through new ways of managing natural resources and facilitating better cities and local communities. Energy, health and welfare, learning for life are our focus areas.

    In constant collaboration and dialogue with our surroundings, regionally, nationally and internationally, we enjoy an open and creative climate for education, research, innovation, dissemination and museum activities. Academic life at the University of Stavanger is organised into six faculties comprising various departments/schools and National Research Centres, as well as the Museum of Archaeology. We are a member of the European Consortium of Innovative Universities. The university is located in the most attractive region in the country with more than 300,000 inhabitants. The Stavanger region has a dynamic labour market and exciting cultural and leisure activities.

    Together with our staff and students we will challenge the well-known and explore the unknown.

    The Faculty of Science and Technology offers study programs at bachelor, master and doctoral level. The faculty has established close cooperation on research with NORCE (Norwegian Research Centre AS) and the regional industry. A number of master's and doctoral theses are made in collaboration with the industry. The faculty has established research collaborations with universities in the US and Europe, and has developed several academic environments that are at the forefront internationally.The faculty has about 2,800 students and approximately 500 employees at the Department of Electrical Engineering and Computer Science, Department of Structural Engineering and Materials Science, Department of Mathematics and Physics, Department of Energy and Petroleum Engineering, Department of Energy Resources and the Department of Safety, Economics and Planning.

    The Department of Mechanical and Structural Engineering and Materials Science carries out research and offers study programs in Offshore Technology, Marine and Subsea Technology, Offshore Wind, Industrial Asset Management, Structural Engineering and Mechanical Engineering. The department has a high international profile with students and staff from around the world. There are currently 60 employees including research fellows and postdocs, and 660 students at the department.

    Deadline

    18th December 2022

    Employer

    University of Stavanger

    Municipality

    Stavanger

    Scope

    Fulltime (1 jobs) Fulltime (%)

    Duration

    Fixed Term

    Place of service

    Ullandhaug

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