| Description: |
Where ?
The two PhD vacancies are available in the "Mechanics of Materials and Structures" group at Ghent University. The offices and laboratories of this group are situated in the centre of Gent (Sint-Pietersnieuwstraat 41, 9000 Gent).
Duration ?
Both PhD vacancies are full-time job positions for 4 years, starting on January 1, 2009 and ending on December 31, 2012. The funds do not allow hiring a post-doctoral researcher.
Job description ?
- The first vacancy is for the research project "Global-local finite element strategies for the simulation of damage in large composite structures under dynamic loading conditions".
The numerical simulation of damage development in large composite structures is very difficult, because the local nature of damage (e.g. a small delamination due to a localized impact of debris) can affect the global response of the composite structure, if the loading conditions are such that the delamination can slowly grow and finally propagate through the structure. To assess the critical stress state in such a region, a detailed finite element mesh is necessary to calculate the in-plane stresses and in particular the interlaminar stresses in between the individual plies. On the other hand, if this fine finite element mesh would be applied to the whole composite structure, the computation would last for months.
The objective of this project is to develop a new finite element analysis strategy for large composite structures where the global and local analysis are combined in one analysis and the successive simulations for damage evolution are done in an computationally efficient manner. The general idea is to use two types of finite elements: (i) a fast-calculating shell element for the major, undamaged part of the composite structure, and (ii) a more computationally intensive element for the damaged regions. The transition from the first element to the latter as damage propagates through the structure, should be made by the finite element software itself in each successive analysis step (depending on critical stress/strain levels, fracture initiation criteria,...), so that the user does not need to know in advance where the damage will initiate and propagate. Airbus has identified the development of these new finite element types for simulation of damage in composites as one of the main targets for the forthcoming years.
This PhD thesis is a purely numerical study, and the amount of experiments will be very little. So a strong background in numerical modelling and computational mechanics is really necessary. As it is the objective to implement the strategies in the commercial finite element code ABAQUS, experience with ABAQUS and Python scripting is certainly an advantage.
- The second vacancy is for the research project "Experimental and numerical study of the slamming wave impact on deformable composite structures". This project is in collaboration with the Department of Fluid Mechanics of Ghent University and the Department of Mechanical Engineering at the Free University of Brussels (VUB).
The objective of this project is the experimental and numerical study of the slamming wave impact on deformable composite structures. Wave impact or slamming is characterized by high local peak pressures (up till 10 bar and more) with a very short duration (typically milliseconds). Two types of slamming are distinguished: (i) bottom slamming, where the structures rises out of the water and then falls back into the water, and (ii) breaking wave slamming, where a wave breaks just at the moment that it hits the structure from the side. In recent years, composite materials are applied more and more in ship construction (catamarans, high speed craft,...) and offshore structures, because of their corrosion resistance, limited maintenance, long life time (up to 20 years) and sometimes even cheaper cost. Moreover, demands of light weight engineering and reduction of material consumption lead to less massive structures that can no longer be considered as rigid. This is basically a good thing, because if the structure allows for any deformation, the local peak pressures induced by slamming waves, will be lower than in the case of a rigid structure. However, the effect of slamming wave impact on deformable composite structures and the evolution of the possible damage has hardly been studied, and there is a need for fundamental research to answer the following questions:
- what is the effect of this very local peak pressure, that moves very fast in time along the surface of the structure, on the local deformation of the composite material ?
- which damage is caused by the repeated wave impact in the composite structure, and can this gradual deterioration of the composite material be modelled in terms of maximum stresses/strains during one single slamming wave impact ?
- what are the possibilities of numerical models with fluid structure interaction, to accurately calculate the local deformations in the composite ? Recently, a lot of numerical studies have been done into the time history of peak pressures and their spatial distribution in case of rigid bodies. The rigid body then enters a fluid mesh with a certain entry velocity and the instantaneous pressure distribution is calculated step-by-step. For deformable composite structures, the value of these simulations has hardly been explored.
This PhD thesis is a combination of experimental and numerical work. Knowledge of the commercial codes ABAQUS (FEA software) or Fluent (CFD code) is an advantage.
Supervisors ?
The supervisors are Prof. Joris DEGRIECK and Prof. Wim VAN PAEPEGEM. Prof. DEGRIECK is head of the department and head of the "Mechanics of Materials and Structures" group. Prof. Wim VAN PAEPEGEM is part-time professor and postdoctoral research fellow of the Fund for Scientific Research - Flanders (F.W.O.-Vlaanderen).
Who do we look for ?
- you are interested in research and have the intention to obtain a PhD degree,
- you have a Master Degree in Mechanical Engineering, Civil Engineering, Materials Science, or similar,
- you are familiar with mechanics of materials, experimental testing methods and computational techniques. Knowledge of composite materials, finite element software (e.g. ABAQUS, SAMCEF, ANSYS,...), programming languages (Fortran, C++) or Unix/Linux environment is an advantage,
- mastering the Dutch language is not a prerequisite, but a good knowledge of English writing and speaking is absolutely required.
What do we offer ?
- you will be working in a dynamic environment. Our group has expanded quite fast the last few years and currently, 13 PhD students are working in our group. Besides, several PhD students have successfully obtained their PhD degree in the last five years,
- we have good contacts with the regional composite industry and regional universities, so you will come into contact with industrial applications of composites and related research in other universities,
- you will get the chance to attend international conferences on composite materials (e.g. ECCM, ICCM,...) and to present papers on these conferences. For those who are interesed, an international exchange with another university is possible. As publications are increasingly important (also for your career afterwards), you are encouraged to publish your results not only on international conferences, but also in peer-reviewed international journals,
- you will have a personal laptop and a private workspace. All PhD students and staff have their office in the same wing of the building. The laboratories are separate in another building,
- if you are just graduated, your net income is 1470 EUR per month. The grant is free from taxes, so that is the amount of money that is deposited on your bank account every month. If you have a dependent wife and/or children, the salary is raised. Also seniority can be taken into account if you can show former relevant experience,
- the university offers compensations for public transport (train) and bicycle. The work location can be reached easily by public transport (train and tram/bus),
- a hospitalization insurance policy can be concluded,
- there are a lot of sport accommodations and other benefits (reductions on computer purchase, internet connection, fitness,...) for university personnel,
- there are specific organizations for the international student community in Gent. There are ISAG (International Students Association Ghent) and ESN (European Students Network). They are quite active in organizing all sorts of events (http://student.ugent.be/isag/ISAG/index.html).
How to apply ?
- you write a detailed Curriculum Vitae in Dutch or English, containing:
- your personal details (name, address, date of birth, nationality,...)
- your education, subject of master thesis and degrees
- your work experience (previous jobs)
- additional skills (finite element software, programming languages, communication skills, ...)
- mastered languages (Dutch, English, French)
- references (previous projects in the domain, published papers,...)
- you send the C.V. by post or e-mail to the following person:
Prof. Wim VAN PAEPEGEM
Ghent University
Mechanics of Materials and Structures
Sint-Pietersnieuwstraat 41
9000 Gent
Belgium
Tel.: +32-(0)9-264.42.07
Fax: +32-(0)9-264.35.87
E-mail: Wim.VanPaepegem@UGent.be
Additional information ?
- you can freely download our annual report. This PDF-document contains a lot of pictures and impressions of our research activities. You can find it on the webpage http://www.composites.ugent.be/ftp/UGent_MMS.pdf
- you can contact Prof. Wim VAN PAEPEGEM for any additional information, either by phone or e-mail or a personal appointment.
|
