Ongoing research projects
Ongoing research projects in iMMC (February 2020)
This a short description of research projects which are presently under progress in iMMC.
Hereunder, you may select one research direction or choose to apply another filter:
List of projects related to: Solid mechanics
|Development of high-toughness cryogenic alloys|
Researcher: Alvise Miotti Bettanini
Supervisor(s): Pascal Jacques
Materials that can perform at extremely low temperatures are in great demand. Applications span from tanks and pressure vessels for LNG (Liquefied Natural Gas) carriers to structural materials in extreme conditions, like the upcoming exploration of Mars. In this context, it is critical to ensure very high toughness, which measures the resistance to crack propagation, at cryogenic temperatures. In this project, the experimental development of Fe-based superalloys is guided by a CALPHAD-based methodology, which allows the calculation of phase stability and phase transformation with computational models in order to reduce the experimental effort and hasten the development cycle of new materials.
|Characterization and physics based modeling of plasticity and fracture of Dual-Phase steels towards ultratough materials by microstructure optimization|
Researcher: Karim Ismail
Supervisor(s): Thomas Pardoen, Pascal Jacques
The research work, in collaboration with company ArcelorMittal, is about the plasticity, the damage and the crack propagation resistance of dual-phase steels, which are commonly used in the automotive industry. A minimum level of fracture toughness is required to prevent the propagation during forming operations of small edge damage or cracked zones induced by cutting. Therefore, unravelling the relationship between fracture toughness, microstructure and damage mechanisms is essential to develop advanced steels with superior forming ability. Furthermore, reaching superior fracture toughness could open to other potential applications.
Experimental works as well as computational modeling are used to study the behavior of such steels. A model for the plastic behavior and for the damage mechanisms related to the microstructure has been developed. A finite element based unit cell approach is used to address the plastic behavior, locally as well as at the macroscopic scale. A particular focus is put on the effect of particle morphology and orientation that have not been much investigated and that considerably affect local mechanical fields, and hence damage and fracture behavior. A two-stage void coalescence process is suggested in elongated microstructures. The data extracted from the elastoplastic analysis are fed into a cellular automaton approach of the damage evolution. This model introduces a statistical description of the material while using relatively simple damage evolution laws. Furthermore, the essential work of fracture method is used to quantify the resistance to the propagation of a crack on thin sheets. Martensite morphology in the form of platelets seems to be a means to reach a high fracture toughness. Finally, damage mechanisms are observed post-mortem and hole expansion ratio tests will be performed.
|CeraMAX / Aerostream|
Researcher: Matthieu Marteleur
Supervisor(s): Pascal Jacques
I am currently working on the processing and characterisation of a particular type of ceramics called MAX phases. They present an intermediate behavior between a ceramic and a metal at high temperature, providing a unique combination of functional properties.
My research projects also include Additive Manufacturing on metallic materials, particularly Al and Ti alloys. I am studying the relationship between the process parameters and the resulting microstructure and properties.
|Contributions to nonlinear micromechanical modeling of composite and porous materials under small and large deformation|
Researcher: Marieme Imene El Ghezal
Supervisor(s): Issam Doghri
The goal of my research is to deliver models able to predict the effective mechanical behavior of materials made of at least two different phases and which can be used for complex loading tests like non-proportional loadings. The adopted technique is the Mean Field Homogenization (MFH). The development of such schemes strongly depends on the constitutive laws of the constituents. The range of materials concerned by this research is wide: elastic, viscoelastic, elasto-plastic (in the small strain regime) and hyperelastic-plastic in the finite strain regime. My research interests also include FE analysis of cellular materials, porous materials and composites involved mainly in the validation of the MFH schemes.
|Observation and modelling of the link between microstructure evolution and strength in plastically deformed and annealed metals with fine-scale twins|
Researcher: Fengxiang Lin
Supervisor(s): Laurent Delannay
This project aims at advancing the current understanding of the evolution of microstructures and strength during plastic deformation of face centered cubic metals in which fine-scale twins influence the dislocation slip activity, the stored energy, and the subsequent annealing. The fine-scale twins can be mechanical twins (e.g. in TWIP steels and high-strain-rate deformed copper) or growth twins in electro-deposited films. These fine-scale twins increase anisotropy, which promotes microscopic shear banding during plastic deformation. This project will specifically address some fundamental questions:
- What is the influence of the interplay of dislocation slip and mechanical twinning on the occurrence of microscopic shear bands (MSBs)?
- What is the influence of MSBs on the deformed microstructure (incl. rotation of twin bundles), the internal stresses, and the stored dislocation density?
- How do hardening and internal stresses (incl. “back-stresses”) develop in small-size samples compared to bulk samples?
- How do structural heterogeneities from MSBs and twin bundles affect the subsequent annealing behavior?
|Finite strain modelling of polymers and continuous fiber reinforced composites|
Researcher: Muralidhar Reddy Gudimetla
Supervisor(s): Issam Doghri
The main thesis goal is to efficiently integrate the constitutive models of resin, fiber and fiber/matrix interface into a mulit-scale approach to predict the behavior of an uni-directional carbon-epoxy composite ply. This would require an efficient constitutive model for the resin/polymer which would address the experimentally observed features like strain-rate, temperature and pressure-dependency. So, an isotropic thermodynamically based fully coupled viscoelastic-viscoplastic model formulated under finite strain transformations was developed considering isothermal conditions, which is further extended to an anisotropic version suitable for structural composites. This model would be implemented in a multi-scale approach, with corresponding models for fiber and fiber/matrix interface, to predict softening/degradation in an uni-directional composite ply.
|Crystal plasticity modelling of thermomechanical fatigue in ITER relevant tungsten|
Researcher: Aleksandr Zinovev
Supervisor(s): Laurent Delannay
Tungsten, selected as plasma-facing material for fusion reactors (such as ITER and DEMO), needs to possess high crack resistance and ductility under extreme operation conditions, such as high neutron flux and cyclic thermal load, which lead to material degradation. The objective of this project is to develop a finite element (FE) model capable to simulate mechanical behaviour of polycrystalline tungsten under tensile testing with the focus made on effect of test temperature and irradiation-induced defects. The input for the model is derived from experiments and lower-scale models, such as crystal plasticity (CP), molecular dynamics (MD) and dislocation dynamics (DD). A combination of FE and CP approach allows for investigation of mechanical behaviour of tungsten at the grain level.
The following scientific questions have to be addressed in the frame of this PhD project:
How does the heterogeneity of stress and strain within grains affect the cracking behaviour of tungsten under ITER-like heat loads? How can the impact of neutron irradiation defects be included in the CP model? What is the effect of texture on anisotropy of plastic deformation and fracture properties?
A macroscopic constitutive law, which describes plasticity of tungsten in the ITER-relevant temperature range, has already been constructed. Based on that, two papers have been published in peer-reviewed journals.
|A dynamic-based approach for road vehicle design optimization|
Researcher: Aubain Verle
Supervisor(s): Paul Fisette, Bruno Dehez
Due to urban zone densification and energy rarefaction, some facets of life habits have to be revised. The mobility doesn’t derogate from this trend and is one of the major future challenges. Automotive industry is developing new solutions to cope with the increasing problem of mobility, the need for energy efficiency and customer requirements. Facing this multiplication of objectives, often conflicting, it is quite unlikely that one particular solution would satisfy all customers in all daily needs as it was with the car until now. Several new kinds of vehicles appear, each of them being able to answer a particular use. In the special case of urban and personal mobility, tilting three-wheelers seem to be a promising solution. Small and agile, they improve the traffic flow while the associated reduction of weight allows better energy efficiency.
Because of the increase – in number and quality – of the criteria imposed to tomorrow’s vehicles, the industry must propose new types of morphologies, incorporate new technologies and detect a maximum of synergies between the latter. Thus we observe a constant increasing design tasks complexity while the development times are shorter than ever. There is a real need for global design methodologies that include, from the earliest stage of the process, a multitude of components among which the dynamics takes place.
This work aims at developing a design methodology especially dedicated to road vehicles. The method has the particularity to enable to manage the trade-off between dynamic performances and mechanical feasibility. The method is being applied to a new three-wheeler under development in our laboratory. The main characteristics of this vehicle are a unipersonal seated position, a narrow track and a electric motorization.
We achieved the design of a first prototype on the basis of the optimization processes. In particular, we develop some very specific mechanical arrangements especially designed to maximize the dynamic performances of the tilting vehicle suspensions. Moreover, it is expected that a first implementation of the prototype will be built in the future to carry out some comparison between experiment and simulation.
|Aerostream and IAWATHA (additive manufacturing), LOCOTED (thermoelectrics)|
Researcher: Camille van der Rest
Supervisor(s): Pascal Jacques, Aude Simar
Camille van der Rest completed her PhD thesis on the optimisation of Heusler Fe2VAl-based thermoelectric compounds through innovative metallurgical processing in 2015. It was under the joint supervision of Prof. Pascal Jacques and Prof. Aude Simar. Her research topics now concern thermoelectric materials, additive manufacturing and friction stir processing technologies. Concerning thermoelectrics, the main objective is the development of low-cost, non-toxic, and powerful materials that could be used in large-scale industrial applications of heat recovery. In addition, she studies some fundamental aspects in order to improve the performances of such materials, i.e. ordering phenomena in off-stoichiometric Fe2VAl-based Heusler compounds. It is essential to make the link between (innovative) manufacturing processes, microstructures and the functional properties of these TE materials. Concerning additive manufacturing, the main contributions are on the characterisation and optimisation of the microstructures and the mechanical behaviour of Al parts obtained by Selective Laser Melting and the developpment of new materials for additive manufacturing. Again, the link between the process parameters and the final microstructure/properties is a key issue. Finally, Camille developed, together with Prof. Aude Simar and Prof. Pascal Jacques, a novel Friction Melt Bonding (FMB) process in order to weld aluminium alloys and steels. This process is still under development thanks to the collaboration with other researchers of IMAP.
|AVATAR² - Aortic VAlve TransApically Resected and Replaced|
Researcher: Xavier Bollen
Supervisor(s): Benoît Raucent
obtained his master's degree in electromechanical engineering, with specialization in mechatronics in 2011 from the Université catholique de Louvain (UCL), Belgium. In 2016, he obtained his PhD degree from the UCL.
During his thesis, under the supervision of Pr. Benoît Raucent and Pr. Parla Astarci (Cliniques universitaires Saint Luc, Brussels), he developed a new device for minimally aortic valve resection. The device was used on patients undergoing open heart surgery in order to validate its design and its functional principle.
Now he still works on the design of the device and he also works on additive manufacturing inside the IMAP department. Since September 2015, he is invited lecturer at the Polytechnic School of Louvain where he teaches technical drawing to the first year bachelor's students in engineering.
Researcher: Audrey Favache
Supervisor(s): Thomas Pardoen
obtained a PhD degree in the domain of process control in 2009 at Université catholique de Louvain (Belgium), after having graduated there as chemical engineer in 2005. Since then, she is working as a "senior" researcher on several applied research projects in collaboration with the industry in the domain of mechanics of materials. More particularly, she is interested in the link between the mechanical properties of the individual components of a complex system and the global mechanical response of this system. She applied this approach to the framework of tribology and contact mechanics for understanding the scratch resistance of coatings and multilayered systems. Her work covers both experimental aspects and finite element simulations.
Researcher: Thaneshan Sapanathan
Supervisor(s): Aude Simar
completed a mechanical engineering degree and a PhD at Monash University (Australia) in 2010 and 2014, respectively. His thesis was entitled “Fabrication of axi-symmetric hybrid materials using combination of shear and pressure”. During his PhD, he worked on architectured hybrid materials fabrication using severe plastic deformation (SPD) processes. Two novel axi-symmetric SPD techniques were investigated to fabricate hybrid materials with concurrent grain refinements. After that, he started a research project at University of Technology of Compiègne (France) in which he investigated the weldability window for similar and dissimilar material combinations using numerical simulations for magnetic pulse welding. He also studied the interfacial phenomena, behavior of material under high strain rate deformation, modeling and simulation of the magnetic pulse welding/forming. Then, I was working as a postdoctoral research fellow at UCL on the topic of characterizations of aluminium to steel welds made by friction stir welds and friction melt bonding. At present, I am working as a FNRS reserch officer (Chargé de recherche) and investigating intermetallic induced residual stresses and mitigation of hot tear in innovative dissimilar joints.
|Numerical modeling of growth and remodeling in stented arteries|
Researcher: Colin Laville
Supervisor(s): Laurent Delannay
The project aims to predict the evolution of the radial contraction of stented arteries using a continuum mechanics model, with application to bio-resorbable stent development. The capture of the stress state evolution in the artery wall requires a material model that includes:
- the modeling of the main constituents such as collagen, elastin and smooth muscles ;
- time dependent evolution such as growth and structural remodeling.
Some developed tools are also used to predict fracture in bended stainless steels.
|Friction stir processing based local damage mitigation and healing in aluminium alloys|
Researcher: Matthieu Baudouin Lezaack
Supervisor(s): Aude Simar
Al 7XXX alloys will be characterized before and after friction stir process (FSP) in order to identify the damage mechanisms. The performances of FSPed alloys will be studied by macromechanical testing. Up to now, a 150% increase in ductility was reached by FSP + heat treatments compared to the base 7475 Al material. Then a numerical model will catch the 7XXX aluminium behavior in a close future.
|Improving the properties of glass fiber reinforced acrylic thermoplastic resin based composites|
Researcher: Sarah Gayot
Supervisor(s): Thomas Pardoen
For the manufacturing of continuous fiber reinforced thermoplastic composites (CFRTP), certain monomers can be infused through glass fabric and then polymerized in situ, in order to make a thermoplastic composite part. However, defects - e.g. porosity - can occur in the material, due to the thickness of the laminates and the shrinkage of the resin matrix during polymerization. Such phenomena must be understood, as well as their effects on the mechanical properties of the final composite part.
The originality of this work lies in the very nature of the polymeric matrix used for manufacturing the composite parts, which is thermoplastic instead of thermoset. Little is known about the behaviour of such thermoplastic composites, especially at a microscopic scale. During this PhD, we will try to understand how defects occurring in the material can influence the structural properties of the CFRTP, and we will try to mitigate (or at least control) the incidence of such defects. This will imply a better knowledge of how usual characterisation techniques can be applied from thin to thick composite parts. In particular, digital simulation will be used so as to predict the properties of thick composite parts from those of thinner samples.