Ongoing research projects

IMMC

Ongoing research projects in iMMC (August 2022)


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:

Biomedical engineering

Computational science

Civil and environmental engineering

Dynamical and electromechanical systems

Energy

Fluid mechanics

Processing and characterisation of materials

Chemical engineering

Solid mechanics


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List of projects related to: micromechanics




DeltaT
Researcher: Valentin Marchal-Marchant
Supervisor(s): Pascal Jacques

obtained his degree in engineering in materials science from the Université catholique de Louvain in 2011. Then, he accomplished his PhD under the supervision of prof. Pascal Jacques, on the study of Physical Vapor Deposition of thick copper films on steel.

His research is now focused on the development of thermoelectric materials and thermoelectric generators for energy harvesting and passive electromechanical systems. It aims at using common and non-toxic materials to generate electrical power from thermal gradients. Nowadays, attention is put on large scale applications owing to more than 7 years of research about thermoelectric materials leaded in IMAP.

The big challenge of this topic is the development of new tools and equipments for material production and assembly, and specific characterization methods. Such a wide range of different tasks can only be achieved thanks to the versatility of technical and scientific expertises of the IMAP team members as well as Lacami support.



Coupled mechanical-electrical effects in highly strained Ge thin films
Researcher: Marie-Stéphane Colla
Supervisor(s): Thomas Pardoen

Graduated in chemical and materials science engineering at the Université catholique de Louvain in 2009 (Belgium). Then, under the supervision of Prof. Thomas Pardoen (iMMC) and Prof. Jean-Pierre Raskin (ICTEAM), she accomplished a PhD on the study of the mechanical properties of thin films, more specifically on the plasticity and creep of freestanding nanocrystalline Pd films. The lab-on-chip technique developed previously at the UCL was adapted to deform Pd thin films. After the PhD, she worked for more than two years at the CRM Group in Liège on the development of industrially viable thin film solar cells on steel. From June 2016 to September 2018, she is back at the UCL as a research engineer involved in projects dealing with the understanding of fracture behaviour of high strength steels under a wide range of strain rates.​ In 2018, she received a 'Chargée de recherches - FNRS grant' and is now working on coupled mechanical-electrical effects in highly strained germanium thin films. Germanium is a promising material for optoelectronic device owing to its compatibility with the standard complementary metal-oxyde-semiconductor (CMOS) technology and to the possibility to convert it into a direct bandgap semiconductor by straining it.



BIODEC, STOCC
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: Sahar Jaddi
Supervisor(s): Thomas Pardoen

The aim of this research is to develop a new testing method based on an-on-chip concept to measure the fracture toughness of freestanding submicron films. This device consists of two major components, a notched specimen and two actuators. When the test structure is released by etching the sacrificial layer, the two actuators contract, this in turn loads the specimen in traction. In order to define the stress intensity factor expression, which is given by this new model, analytical analysis and finite element simulations must be performed in addition to the experimental part, which is based on the microfabrication techniques. Silicon nitride, silicon oxide and metallic glass thin films will be studied during this work. The major goal of this model is to extract fracture toughness of 2D materials like graphene.



Development of thermo-tensile nano devices operating ex situ or in situ in transmission electron microscopes (TEM)
Researcher: Alex Pip
Supervisor(s): Hosni Idrissi

The main goal of my research project is to develop modern miniaturized devices dedicated to quantitative small-scale thermo-tensile testing in-situ inside a transmission electron microscope. These unique devices will be used to investigate the effect of T on the plasticity/failure mechanisms in selected materials, nanocrystalline palladium films and olivine. My project builds up on already existing MEMS devices, namely the commercial Push-to- Pull from Bruker.Inc and UCLouvain’s ‘lab-on-chip’ nano tensile testing devices. Currently, those devices are limited to room temperature experiments. My work will be dedicated to the integration of heating systems inside these two devices, in order to heat samples up to hundreds of °C. This will allow performing in-situ TEM thermo-tensile tests on Pd films and olivine samples where the coupling between tensile loading and heating could lead to unprecedented results regarding the effect of T on the mechanical response and the plasticity/failure mechanisms.

This project has a direct application in the field of geology, as one of the selected material is olivine, the material that makes up most of the upper part of the Earth’s mantle. Thermo-tensile testing of olivine at the micro/nano scale will bring crucial data about its rheology under conditions similar to the Earth’s mantle. This part of the project involving olivine will be performed in close contact with prof. Patrick Cordier and his team at UMET (Université de Lille). The other selected material is Pd, a material that is well known by the UCLouvain’s IMMC researchers used here as a benchmark. I will mostly work within the WINFAB platform, where I will develop and build the new thermo-tensile devices using the nanofabrication equipment. As theses devices are expected to be used in-situ inside a TEM, I will also partly work at the EMAT research center (UAntwerpen).




Analysis and understanding of the damage and fracture mechanisms in advanced high strength steels for automotive applications
Researcher: Thibaut Heremans
Supervisor(s): Pascal Jacques, Thomas Pardoen

The environmental challenge the world is facing today is driving car manufacturers to limit their vehicule weight in order to reduce their fuel consumption. As a consequence, steels with higher specific strength performances are being constantly developed, while insuring that proper ductility and toughness levels are retained to allow for forming operations and passengers safety. Lately, the so-called "third generation" of advanced high strength steels (AHSS) has emerged, among which one finds the Quenching & Partioning (Q&P) steels. These Q&P steels demonstrate an excellent combination of ultimate tensile strength (UTS = 1500 MPa) and adequate ductility (TE = 18%). Nevertheless, their fracture properties and the underlying mechanisms are still not fully understood and start raising concerns as the strength levels of these steels increase. Indeed, recent studies have highlighted a shift in failure mechanism, from ductile to brittle, depending on the loading conditions. Although often left behind strength and elongation, toughness issues constitute essential stakes not only for ever more demanding applications but also for forming processes during which edge cracking is a key concern. The objective of my research project is to investigate the failure properties of these Q&P steels in order to understand how microstructural and micromechanical parameters influence the competition between three possible mechanisms : ductile flat, ductile slant and brittle intergranular.



Micromechanics of crystallization of thermoplastic matrices in the interfiber regions of high-toughness composites
Researcher: Sophie Vanpée
Supervisor(s): Thomas Pardoen

A major effort is being made all over the world by industrial and research actors to lead the technological mutation of the field of advanced continuous fibers polymer composites from the current use of thermosetting matrices to thermoplastic ones which gather economic (increased production rates), environmental (recyclable) and performance advantages (tougher matrices). However, until recently, this transformation was strongly hindered by processing difficulties. Today, a precise prediction of the behavior of these materials based on the processing conditions becomes essential for many actors, such as the company Solvay, the industrial partner of the present thesis.















It is in this context that the thesis will be carried out. The objective of the STOUGH project is to unravel the influence of the composite microstructure on the kinetics and morphology of crystallization within the matrix, particularly in the neighborhood of fibers, in order to evaluate their influence on mechanical properties of the matrix and, hence, of the composite. The project is thus intrinsically multi-scale, which necessitates a combination of analyses at the different levels of the composite system, from its constituents themselves to the unidirectional (UD) ply level and eventually to the macroscopic composite.















The main questions are around the positive or negative impact of the conditions and the type of crystallization on the fracture toughness via local damage or decohesion of the fibers, as well as on the transfer of these effects to the macroscopic scale and the properties of use. To do so, it is necessary to understand what makes the behavior of the semi-crystalline polymer confined between fibers and the non-reinforced version of the same polymer different, and how factors related to transcrystallization condition the local mechanical behavior. Does the crystal morphology induce a local softening of the strength or the opposite? Are macroscopic constitutive models adaptable to this scale? Do the local internal stresses affect the first order strength of the interfaces? These are some of the major scientific questions that motivate the fundamental side of this project and justify the framework of a PhD thesis in collaboration with Solvay.















The thesis will be based on an innovative methodology relying on the use of the appropriate experimental methods for each level of investigation. For instance, it will combine atomic probing and nanoindentation for the nano- and microscopic characterization of the matrix, fiber-matrix interface properties measurements, image correlation analyses at the scale of the representative volume of the UD ply as well as macroscopic tests at the coupon level. Additionally, the project will also include the specimens processing and manufacturing steps, as well as numerical aspects to incorporate the acquired knowledge in existing models.