PhD position Multi-scale modelling of thermo-mechanical fatigue, Netherlands

Physics of Failure: Programme description
The objective of the programme ‘Physics of Failure’ is to unravel the physical complexity of the initiation and development of damage and failure in complex and dynamically changing microstructures in metals. Existing physical models of the initiation and propagation of damage in metallic materials are limited in terms of the specific microstructural features and physics accounted for. The physics of damage involves interacting processes and mechanisms at the nano-, micro- and macro-scale, i.e. from processes at the nano-scale (atomic behaviour, dislocation dynamics, interaction with grain boundaries and interphase boundaries) through damage development within the grain structure at a micro-scale to macroscopic failure. The systematic scientific approach adopted in the programme will lead to comprehensive physical models of damage and failure in metallic microstructures, enabling predictive modelling for a more accurate assessment of performance and (remaining) life time of metallic components. The programme combines projects that put an experimental focus on the microstructural damage mechanisms in metals, as well as projects focusing on modelling the accompanying physics across the length scales. The intensive interaction between the projects enables the development of an in-depth view on the evolution of damage and failure in metallic microstructures, which goes well beyond the state-of-the-art in the field.

Aim of the PhD project
Within the wider scope sketched above, the present PhD project focuses on Thermo-Mechanical Fatigue (TMF) failure of compacted graphite cast iron (CGI), typically used by DAF trucks in heavy duty truck engines, which is a material subjected to TMF conditions (engine start-up/shut-down cycles). The goal of this project will be the development of a predictive multi-scale physical model for the TMF failure of a cast iron material, which is a typical case of a microstructurally complex material subjected to complex loading conditions. The model will allow unravelling of the critical conditions triggering microstructural damage initiation, propagation and ultimate failure as a function of microstructural and loading variables. This project is closely related to another research project within the programme, focusing on the experimental quantitative characterization of failure processes in cast iron.

A physically-based multi-scale framework will be developed, incorporating two spatial scales: the macro-scale will be represented by a valve bridge area of the cylinder head engine component, while the micro-scale will be described by a representative microstructural model at the scale of the graphite inclusions in the matrix. The physically-based microscale model including all relevant physical phenomena will be developed and calibrated on the basis of quantitative data from the experimental characterization performed in a parallel project at TU Delft.
The spatial scale transition, based on the continuous-discontinuous computational homogenization framework, will enable a two-way coupling between a growing crack at the macroscopic (valve bridge) scale and the physical micro-scale phenomena. In addition, to represent the TMF conditions, two temporal scales will be incorporated: the fine temporal scale corresponding to the time of one start-up/shut-down cycle and the coarse temporal scale representing the life time of the engine. A temporal scale transition scheme will be developed, enabling an efficient simulation of TMF conditions involving tens of thousands of cycles.

Job description
This PhD position is available in the Mechanics of Materials group led by Prof.dr.ir. Marc Geers (FOM working group FOM-E-18). This PhD project is part of a FOM Industrial Partnership Programme (IPP) ‘Physics of Failure’, which aims at unraveling the physical complexity of the initiation and development of damage and failure in complex and dynamically changing microstructures in metals. The work is to be carried out in close collaboration with other PhD students, faculty members, and industrial partners, of which DAF Trucks is directly involved in this particular project.

Location
Research group Mechanics of Materials
The scientific research activities in the Mechanics of Materials group concentrate on the experimental analysis, theoretical understanding and predictive modelling of a range of phenomena in engineering materials at different length scales, which emerge from the physics and the mechanics of the underlying multi-phase microstructure. The main challenge is the accurate prediction of the mechanical properties of materials with complex microstructures. This focus is closely related to intrinsic material properties (multi-scale plasticity in advanced steels, interfacial properties in laminates, thermo-mechanical fatigue in cylinder heads etc.), the application of materials in microsystems (i.e. multi-phase functional materials, MEMS, stretchable electronics etc.) and various systems and processes involving mechanically complex interfaces (e.g. in Systems in Package, flexible displays, electronic textiles). The aim is a substantial increase of the predictive power of state-of-the-art models, thereby enabling the optimization of critical, high-tech products and manufacturing processes in direct relation to the complex loading history of the underlying materials and joining interfaces. A systematic and integrated numerical-experimental approach is generally adopted for this purpose.
The group has a unique research infrastructure, both from an experimental and computational perspective. The Multi-Scale Lab allows for quantitative in-situ microscopic measurements during deformation and mechanical characterization within the range of 10-9-10-2 m. In terms of computer facilities, several multiprocessor-multi-core computer clusters are available, as well as a broad spectrum of in-house and commercial software.

Job requirements

Talented, enthusiastic candidates with excellent analytical and communication skills are encouraged to apply. A MSc degree in Mechanical Engineering, Applied Mathematics or Computational Physics or a related discipline is required, as well as a strong background in mechanics and computational methods. Experience in homogenization, multiscale modeling, micromechanics, and non-linear finite element techniques are of benefit.

Conditions of employment

When fulfilling a PhD position at the FOM Foundation, you will get the status of junior scientist.
You will have an employee status and can participate in all the employee benefits FOM offers. You will get a contract for four years. Your salary will be up to a maximum of 2.717 euro gross per month.The salary is supplemented with a holiday allowance of ۸ percent and an end-of-year bonus of 8,3 percent.
You are supposed to have a thesis finished at the end of your four year term with FOM.
A training programme is part of the agreement. You and your supervisor will make up a plan for the additional education and supervising that you specifically need. This plan also defines which teaching activities you will be responsible (up to a maximum of 10 percent of your time). The conditions of employment of the FOM Foundation are laid down in the Collective Labour Agreement for Research Centres (Cao-Onderzoekinstellingen), more exclusive information is available at this website under Personeelsinformatie (in Dutch) or under Personnel (in English).
General information about working at FOM can be found in the English part of this website under Personnel. The ‘FOM job interview code’ applies to this position.

Information and application

Contact: Dr. Varvara Kouznetsova, Dept. Mech. Engineering, Eindhoven University of Technology
Website: http://www.tue.nl/mechmat
Applications: You can only respond to this vacancy online via the button below.

Application documents (in pdf format) must contain: letter of motivation, detailed curriculum vitae, transcripts of BSc and MSc grades and contact information of two potential referees.

Further Information

Application Deadline : 31 December 2015

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