PhD student in Mechanics of Stone-Based Infrastructure Materials at Large Deformations, KTH, Sweden
Project Description
Stone-based composite materials, i.e. asphalt, concrete and unbound granular materials, are the most common materials in pavement construction. In all these materials stones occupy most of the volume and stone-to-stone contacts provide an important load carrying mechanism in compression and shear. However, with respect to large deformation of stone-based materials, asphalt is considered the most general material for this study because of its thermo-rheological and spacial complexity that allows to incorporate all relevant effects in a broad range. Hence, the computational framework developed in the present project will be primarily applied to investigate asphalt behavior at large deformations. Large deformation performance of asphalt mixtures under compressive and shear loads is of significant importance at all stages of the materials life starting with asphalt production and lay down and continuing with its functional behavior (e.g. rutting) throughout the pavement service life. There is significant experimental and theoretical evidence that stone-to-stone contact conditions control to a great extent the performance of asphalt mixtures in these situations. Therefore, state-of-practice material design methods put requirements on gradation (the distribution of stone sizes in a batch), shape, texture as well as on mechanical properties of the stones. These requirements rely however heavily on empirical evidence, and presently there are no comprehensive mechanics-based models, relating stone and binder material parameters to the mixture performance at large deformations.
The present project is intended to fill this gap by investigating theoretically, numerically and experimentally the mechanical behavior of the asphalt mixtures at elevated temperatures and large deformations. As stone to stone contact is the primary load transferring mechanism to be accounted for, the best physical insight into the problem can be achieved by understanding the mechanical behavior of the material from an analysis based on fundamental micromechanical principles. In the present project, such an analysis will be performed by using the discrete element method (DEM). Special challenge will be to account for the crushed stones that asphalt is made of as compared to cement concrete. In order to validate and calibrate the DEM model developed, the mechanical behavior of asphalt mixtures will also be investigated experimentally. The project implies the opportunity to profit from synergies that are possible through international research Empa, Swiss Federal Laboratories for Materials Science and Technology (Prof. Manfed N. Partl).
Eligibility and Assessment Criteria
The potential candidate must have a master’s degree in Mechanical Engineering, Material Physics, Computational Mechanics or Civil Engineering (with a focus on mechanics). Basic knowledge in solid mechanics, computational modeling and materials is required and a specialization in solids and structures, solid mechanics and/or composite materials is an asset. Previous experience with DEM modeling of granular materials and experimental mechanics is a plus, though not a requirement.
The candidate should be highly motivated for doing scientific research and should have well developed analytical and problem solving skills as well as an interest and curiosity for different types of computational and advanced experimental methods.
Application
The application must include following documents:
1. Compulsory cover sheet, see Cover sheet/Försättsblad
2. CV (maximum 2 pages) including education and relevant academic/work experience
3. Cover letter (maximum 1 page)
4. Official record of transcripts and copy of degree certificate
Above described documents should be attached as word or pdf files.
Applications should be emailed no later than 6th of May, 2013 to: registrator.tsc@abe.kth.se
Please indicate reference number A-2013-0378 in the e-mail subject.
Deadline for application is: 2013-05-06
Form of employment: Time-limited
Work time: Full time
The salary follows the directions provided by KTH
Start date: According to agreement
Contact
Denis Jelagin
Phone: +46 8 790 8698
E-mail: denis.jelagin@abe.kth.se
Trade Union representativeLars Abrahamsson, SACO
Phone: +46 8 790 7058
E-mail: lars.abrahamsson@ee.kth.se
Project Description
Stone-based composite materials, i.e. asphalt, concrete and unbound granular materials, are the most common materials in pavement construction. In all these materials stones occupy most of the volume and stone-to-stone contacts provide an important load carrying mechanism in compression and shear. However, with respect to large deformation of stone-based materials, asphalt is considered the most general material for this study because of its thermo-rheological and spacial complexity that allows to incorporate all relevant effects in a broad range. Hence, the computational framework developed in the present project will be primarily applied to investigate asphalt behavior at large deformations. Large deformation performance of asphalt mixtures under compressive and shear loads is of significant importance at all stages of the materials life starting with asphalt production and lay down and continuing with its functional behavior (e.g. rutting) throughout the pavement service life. There is significant experimental and theoretical evidence that stone-to-stone contact conditions control to a great extent the performance of asphalt mixtures in these situations. Therefore, state-of-practice material design methods put requirements on gradation (the distribution of stone sizes in a batch), shape, texture as well as on mechanical properties of the stones. These requirements rely however heavily on empirical evidence, and presently there are no comprehensive mechanics-based models, relating stone and binder material parameters to the mixture performance at large deformations.
The present project is intended to fill this gap by investigating theoretically, numerically and experimentally the mechanical behavior of the asphalt mixtures at elevated temperatures and large deformations. As stone to stone contact is the primary load transferring mechanism to be accounted for, the best physical insight into the problem can be achieved by understanding the mechanical behavior of the material from an analysis based on fundamental micromechanical principles. In the present project, such an analysis will be performed by using the discrete element method (DEM). Special challenge will be to account for the crushed stones that asphalt is made of as compared to cement concrete. In order to validate and calibrate the DEM model developed, the mechanical behavior of asphalt mixtures will also be investigated experimentally. The project implies the opportunity to profit from synergies that are possible through international research Empa, Swiss Federal Laboratories for Materials Science and Technology (Prof. Manfed N. Partl).
Eligibility and Assessment Criteria
The potential candidate must have a master’s degree in Mechanical Engineering, Material Physics, Computational Mechanics or Civil Engineering (with a focus on mechanics). Basic knowledge in solid mechanics, computational modeling and materials is required and a specialization in solids and structures, solid mechanics and/or composite materials is an asset. Previous experience with DEM modeling of granular materials and experimental mechanics is a plus, though not a requirement.
The candidate should be highly motivated for doing scientific research and should have well developed analytical and problem solving skills as well as an interest and curiosity for different types of computational and advanced experimental methods.
Application
The application must include following documents:
1. Compulsory cover sheet, see Cover sheet/Försättsblad
2. CV (maximum 2 pages) including education and relevant academic/work experience
3. Cover letter (maximum 1 page)
4. Official record of transcripts and copy of degree certificate
Above described documents should be attached as word or pdf files.
Applications should be emailed no later than 6th of May, 2013 to: registrator.tsc@abe.kth.se
Please indicate reference number A-2013-0378 in the e-mail subject.
Deadline for application is: 2013-05-06
Form of employment: Time-limited
Work time: Full time
The salary follows the directions provided by KTH
Start date: According to agreement
Contact
Denis Jelagin
Phone: +46 8 790 8698
E-mail: denis.jelagin@abe.kth.se
Trade Union representativeLars Abrahamsson, SACO
Phone: +46 8 790 7058
E-mail: lars.abrahamsson@ee.kth.se
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