Postdoc in Cognitive Neuroimaging: Relating space, time and number processing in the human brain (1.0 FTE)
Ongeveer 19 uur geleden - Universiteit Utrecht - Utrecht
PhD student "Unravelling the physics of hygro-expansion of paper fibres and sheets"
(V35.2976) in the section Mechanics of Materials, at the Department of Mechanical Engineering.
The mission of the section Mechanics of Materials is to develop and innovate the scientific tools to understand, describe, predict and optimize the mechanical response of industrially relevant materials and products as a function of their underlying microstructure, processing and evolution, through focused and coordinated experimental, theoretical and computational efforts at a wide range of length scales and at the highest scientific level.
Description of project "Unravelling the physics of hygro-expansion of paper fibres and sheets" The processes underlying hygro-expansion at the level of the fibre network of paper are understood only partially and mostly qualitatively. It is clear that cellulose fibres expand transversely upon wetting and this ultimately causes the expansion of the paper sheet. Mutual mechanical constraint between the fibres in the fibre-to-fibre bonds has a major effect on the sheet-level hygro-expansive response, as has been demonstrated by recent micromechanical modelling work. However, quantitative fibre properties which would render such models predictive are lacking, since experiments at the level of single fibres and fibre bonds have proven to be highly challenging. For this reason also, the microstructural origin of the irreversibility in hygroscopic strain is unclear even at a qualitative level. Several possible underlying microstructural processes have been coined in the literature, both at the level of the fibres and the network, but conclusive evidence is lacking for all of them.
We aim to address the above issues by a dedicated, quantitative experimental study of the hygro-expansion of fibres at the micro scale, of fibre networks at the meso scale, and paper sheet at the macro scale; all under different degrees of restraint. To this end, advanced microscopy will be combined with novel digital image correlation techniques to overcome current experimental limitations. Emphasis will be on revealing the main microstructural phenomena underlying irreversible hygroscopic strain and quantifying them. Therefore, the aim of the project is to provide a conclusive and quantitative answer to a long-standing question in paper physics: 'How does irreversible hygroscopic strain arise?'
Tasks As PhD-student in the project "Unravelling the physics of hygro-expansion of paper fibres and sheets" you will fulfil the following activities:
Candidate for PhD position should meet the following requirements:
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