Context and work environment
Structure description: The PhD will be hosted at the Soils, Solids, Structures, Risks laboratory (3SR, Univ. Grenoble Alpes) in Grenoble, and will work in close collaboration with the Néel Institute.
Team description (N+1 and colleagues): The research will be supervised by Sabine Rolland du Roscoat (Professor, 3SR), expert in X-ray imaging of fibrous materials under loading and Julio Caesar da Silva (Researcher, Institut Neel), expert in hierarchical X-ray imaging of materials. The team will also involve Adrien Didier (Assistant Professor, 3SR), specialized in experimental mechanics, and Laurent Orgéas (Researcher, 3SR), who is an expert in mechanics of fibrous cellulosic materials.
This recruitment takes place within the PhD@Tec21 Programme, which is co-funded as part of the Marie Skłodowska-Curie COFUND actions under the grant agreement #101217261. The recruitment process follows a specific selection and evaluation procedure with particular eligibility criteria, all of which are detailed in the applicant guide available on PhD@Tec21 Website.
Mission and main activities
MAX-WOOD: Multiscale Analysis by X-ray tomogaph of WOOD densification
Description of the project: Among cellulose-based materials, wood has a naturally ideally structured cellular microstructure composed of very strong, crystalline cellulose microfibrils embedded in a matrix of porous biopolymers. The longitudinal Young's modulus of the walls of these cells/fibers is on the order of 50-60 GPa, and their failure strength is in the GPa range, close to the best petrosourced fiber-reinforced composites. However, due to a high porosity, the mechanical properties of wood at larger scales are unfortunately lower that the ones of the fibers. One way to increase these properties is to combine a controlled delignification process of wood cell walls with an optimized densification of the cellular structure. It is then possible to obtain a longitudinal Young's modulus of 50 GPa and a tensile strength of 500 MPa. More recently, the work carried out at 3SR lab has led to the foundation of a greener and more efficient process involving delignification by chemical and thermal processes followed by densification by wet compression molding.
In order to optimize the process, there is a need to better understand the effect of the delignification and densification processes across the multiple scales of the wood structure, from meso- to micro- and nano-scales.
X-ray micro- or nano-tomography is a powerful method to address these questions, providing high-resolution 3D non-destructive imaging of a material's internal structure under load, with voxel sizes ranging from 200 µm down to 16 nm. Moreover, the 3D images obtained during an in situ test can potentially be processed to obtain microstructural information at the relevant scales to quantify wood cell walls deformation during delignification and densification tests. However, the hierarchical microstructural method, developed in materials science, has never been applied to wood because of its natural heterogeneity and its highly anisotropic structure. There is currently no experimental set-up available to monitor simultaneously the meso and microscale during the processes of delignification, and compression.
The MAX-WOOD project will leverage the new MUSITOX instrument developed at UGA, a unique laboratory X-ray tomography designed to allow simultaneous acquisition at two different spatial resolutions. The main challenge of the project will be to extend the imaging capabilities of MUSITOX to highly anisotropic, materials and to combine these data with nano-scale data obtain at ESRF synchrotron facility.
Main research axes:
- Multiresolution and real time lab X-ray tomography at meso and microscales ( 2µm and 20µm typically). Develop a robust methodology to correlate low- and high-resolution data in hierarchical anisotropic porous structures; quantify deformation mechanisms through advanced image processing routines; monitor and characterize the effects of delignification and densification processes.
- Linking micro- and nano-scales 3Danalyses Post-mortem nanoscale imaging using synchrotron facility to visualize and quantify the deformation and damage mechanisms at the interface between fibers or inside wood fiber cell walls
The two work packages are in direct relation to the two following hot topics in research:
This research will advance
- Experimental mechanics by bridging the gap between the nano, meso and micro scales in X-ray imaging during in situ tests, and well as
- Provide unique insight in view of producing structural materials greener than petro-sourced materials and exhibiting high mechanical performances.
Supervisors: Sabine Rolland du Roscoat, Adrien Didier and Julio Caesar da Silva Research fields: wood science, experimental mechanics, X-ray imaging, field measurement,
Possible secondments (industrial or academic partners): If the PhD student prefers methodological development, she/he can have a secondment at a large-scale facility such as MAXIV that has a beamline dedicated to biosourced materials (https://www.maxiv.lu.se/beamlines-accelerators/beamlines/formax/) or DTU University that has an advanced lab X-ray tomography (https://www.isa.energy.dtu.dk/lab-facilities/x-ray). If the PhD student is more interested in materials science, she/he can have a secondment at Ghent or Uppsala universities. An industrial secondment at FCBA (French Technological Institute for the wood sector) is also possible.
Doctoral school: ED IMEP2 : Engineering – Materials, mechanics, environment, energy, processes, production
Desired profile and expected skills
Education, diplomas
Master’s degree (or equivalent, MSc/Engineer) in one of the following fields:
- Materials science and engineering
- Mechanical engineering (with knowledge of materials characterization)
- Physics (with knowledge of materials characterization)
Background in X-ray imaging or wood science would be an asset.
Disciplinary skills, experience
Solid understanding of X-ray imaging (physics or image processing) and/or mechanical behaviour
Experience in one or more of the following areas:
- 3D X-ray imaging of fibrous structures: data acquisition or reconstruction or processing
- Characterization of porous materials (e.g. density, porosity, mechanical or thermal properties)
- Mechanical characterization
Personal skills
- Strong motivation for experimental research and interest in sustainable construction materials.
- Scientific curiosity and analytical thinking, with the ability to link physical phenomena across different scales.
- Autonomy, rigor, and good organizational skills for experimental design and data analysis.
- Team spirit and good communication skills — ability to work in a multidisciplinary environment (materials, process, environmental sciences).
Employment benefits and conditions
Université Grenoble Alpes (UGA) is offering a 36-month full-time work contract.
In line with the European Commission rules for Marie Skłodowska-Curie grant holders, the remuneration will consist of a gross monthly salary of 2,650 EUR. The estimated net salary to be perceived by the PhD fellow will be between 2,050 and 2,150 EUR.
Benefits include:
- Access to a high-quality work environment, including a personal computer, scientific equipment and access to library and shared lab facilities
- Access to high-level scientific and inter-sectoral training through 120 hours of doctoral courses and workshops
- Opportunity for 2-month secondments at an academic institution or industrial partner during the 2nd year of the PhD
- A vast choice of networking events and activities within the PhD@Tec21 Programme and through the international network of MSCA fellows
- Access to the UGA International Student Office, to assist the PhD fellows in searching for accommodation in Grenoble and support with administrative issues including visas, health, bank accounts, etc.
- Visa fees and registration to the UGA Doctoral School are covered by PhD@Tec21
- 45 days of paid holidays
- Sick leave
- Parental leave
General information
Contact for the questions related to the position:
PhD@Tec21 Management Board:
guillaume.chambon@univ-grenoble-alpes.fr / amelie.bataille@univ-grenoble-alpes.fr
