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IMMC

Aude Simar
Professor
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Recent publications

Aude Simar has as main research topic the mechanical behavior of light metallic alloys (mainly aluminum, but also magnesium and titanium). Her focus is on material processing in particular by additive manufacturing (Selective laser melting) and friction stir welding and processing. She studies the link between the material structure, the process conditions, the resulting microstructural features and the mechanical properties including damage, fatigue, impact and toughness. She recently received an ERC starting grant (ALUFIX project) to develop new self-healing aluminum based materials and mitigate damage in existing aluminum alloys.

IMMC main research direction(s):
Processing and characterisation of materials
Solid mechanics

Keywords:
additive manufacturing
fracture mechanics
metallurgy
micromechanics
nanocomposites
plasticity
welding and joining

Research group(s): IMAP

PhD and Post-doc researchers under my supervision:

Florent Hannard

graduated as a materials science engineer at Université catholique de Louvain (Belgium) in 2013. He is currently doing a PhD thesis (funded by a FRIA grant), started in September 2013 and under the joint supervision of Prof. Thomas Pardoen and Prof. Aude Simar from UCLouvain. His research focuses on the contribution from microstructure heterogeneities on the micromechanisms of ductile damage and cracking in metallic alloys. In order to address these effects on damage accumulation, a combined experimental and a modeling strategy is developed. The experimental strategy relies on in situ tensile testing coupled to 3D microtomography, in situ laminography during sheet loading and a variety of more classical mechanical tests. A cellular automaton type modeling is used to capture particle size distribution and cluster effects on the void nucleation and coalescence processes. His project also involves the use of friction stir processing (FSP) in order to increase the ductility of industrial aluminium alloys of the 6xxx series. From an applicability viewpoint, this method has the potential to locally improve ductility of sheets at locations where forming involves large strains or of structural components at stress concentration points.

Sophie Ryelandt

graduated as a physical engineer at Université catholique de Louvain in 1991. After having worked for six years at the R&D center of the Spadel company, she came back at UCLouvain as a senior scientist. She is involved in various applied research projects in collaboration with the industry. Her research domains are dealing with material science, metallic composites, multilayered materials and coatings, additive manufacturing of metals, nanomechanical and mechanical testing and the link between microstructure and mechanical properties.

LongLifeAM & MultiMat3D (additive manufacturing)
Camille van der Rest

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 additive manufacturing, friction stir processing and thermoelectric 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 Laser Powder Bed Fusion and the developpment of new materials for additive manufacturing. The link between the process parameters and the final microstructure/properties is a key issue. The optimisation of the post-treatments, both thermal treatments and Friction Stir Processing (FSP), is another of her research topics in order to reach improved mechanical properties. Finally, multi-material additive manufacturing is also studied, in order to understand the influence of both metallic alloys and their interactions (diffusion, reaction,...) on the final microstructures and properties.
On another hand, 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.
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.

WAALU: wire arc additive manufacturing (WAAM) of high strength aluminium alloys
Matthieu Baudouin Lezaack

The WAALU project aims at manufacturing structures in high strength aluminium alloys by wire arc additve manufacturing (WAAM). The WAAM application on aluminium alloys is currently limited to easy to weld alloys (Mg enriched 5xxx series). The WAALU project is investigating the feasability of deposing high strength alloys like 2xxx and 7xxx series by WAAM technique. The current challenges are the need of manufacturing aluminium wires in the targetted series and the identification of the WAAM working parameters to avoid deposition defects in the built pieces. Step by step, the project proposes a methodology for processing the high strenght alloys by WAAM, with extensive characterization of the obtained microstructures. Mechanical performances of printed parts are extracted in all configuration, in order to achieve excellence in WAAM manufacturing in Belgium.

Vieillissement thermomécanique des brasures d'assemblage de composants électroniques pour applications spatiales
Vincent Voet

Les développements d’électroniques pour applications spatiales nécessitent de garantir une durée de vie de 15 ans avec une probabilité d’échec très faible. L’objet de la recherche sera d’établir des outils de conception permettant l’analyse préalable du comportement en fatigue de ces équipements électroniques. La fatigue des circuits électroniques est dominée par la rupture des brasures des composants montés sur circuits imprimés. Une fois solidaires du circuit imprimé, les brasures subissent tout au long de leur vie des contraintes thermomécaniques liées entre autres à l’inhomogénéité des différents coefficients de dilatation thermique des matériaux qui constituent le montage. Chaque composant combiné à chaque type de report doit donc être caractérisé en vieillissement. Cette caractérisation consiste à réaliser des centaines de cycles thermiques en étuve. Ces essais de vieillissement accélérés prennent plusieurs mois et sont coûteux d’où le besoin de pouvoir estimer les probabilités d’échec ou de succès de façon anticipée.
Cette évaluation permettra de donner un intervalle de confiance sur le succès ou l’échec de la qualification d’un nouveau report de composant ou de l’extrapolation d’un report qualifié dans un environnement étendu. La construction de ces outils sera basée sur de la caractérisation par plans d’expériences physiques ou virtuels et de l’analyse de données relatives aux essais déjà réalisés dans le passé par Thalès Alenia Space.
L’analyse des mécanismes et conditions de fissuration impliquera notamment: Métallurgie des brasures SnPb en lien avec les paramètres de fabrication; Identification de lois de comportement thermoviscoplastiques des brasures SnPb à l’aide de la nanoindentation instrumentée; Calcul, par méthodes numériques, des champs de contraintes dans les composants et les brasures, provoqués par l’inhomogénéité des coefficients de dilatation thermique des constituants sur base du modèle constitutif choisi, de la géométrie locale de la soudure et des paramètres identifiés ;Identification des mécanismes de propagation de fissures et identification des liens avec la géométrie et la métallurgie ; en particulier, un élément clé est de pouvoir déterminer la part prise par la phase d’initiation versus propagation des fissures, dans le but éventuel de justifier qu’une des deux puisse être négligée. Dans ce cadre, il est prévu de générer des soudures avec des défauts artificiels contrôlés afin de voir leur impact sur le processus d’initiation de la fissuration, et de le quantifier. L’utilisation de la microtomographie exploitant aussi la corrélation d’image volumique sera un élément important à ce niveau; Vieillissement des brasures sur base des lois de vieillissement établies ; Quantification des incertitudes par approche statistique et probabilité à partir des données expérimentales et également par variation des paramètres clés dans leur plage d’incertitude (défauts géométriques, variations des paramètres constitutifs, présence des pré-défauts, variations de T° extrêmes, etc); Estimation d’un intervalle de confiance préalable de succès ou d’échec des essais envisagés.

Improving the fatigue life of high strength aluminum parts (7xxx) produced by laser powder bed fusion
Nicolas Nothomb

Laser Powder Bed Fusion (L-PBF) is a fast-growing metal Additive Manufacturing (AM) technique (commonly known as 3D printing) that allows for complex part manufacturing and small production series. One of the main drawbacks is the limited material palette currently available and the often poor fatigue performance of the resulting parts. Currently, L-PBF does not allow the production of high performances aluminium alloys parts adapted for the aerospace industry. Indeed, these alloys exhibit severe cracking due to the high thermal gradients during L-PBF process.

The overarching objective of my PhD thesis project is to overcome the challenges of the L-PBF processing of the 7xxx series Al alloys in order to improve their fatigue life. This objective involves the elimination of the three classical issues associated with this process ; (i) the elimination of the deleterious hot cracking, (ii) closing of the porosity and (iii) overcoming the poor surface quality classically observed for AM components. The proposed approach has two major advantages. First, the application of friction stir processing (FSP) to selected regions of structural components ensures defect-free microstructures at locations of stress concentration. This is essential to enhance the quality and reliability needed for generalizing the adoption of metal AM for structural components. Indeed, even very small fractions of porosity will affect fatigue properties. Second, the surface roughness is improved in situ, i.e. AM components can be used in as-printed condition, as opposed to classical surface post-treatments currently preventing the design of AM components with complex internal geometries (where surface finishing by conventional post-treatments is impossible).

Mechanisms leading to failure under static or cyclic loading will be analysed using in-situ techniques (microtomography and crack propagation with image correlation).

Sanjay Channappa Krishnamurthy

Design and characterisation of a new self-healing high strength aluminium alloy produced by additive manufacturing
Sophie De Raedemacker

Laser powder bed fusion (LPBF) is a rapidly growing technique for additive manufacturing of metal parts in the aerospace and automotive industries. The parts used in these two fields can be subjected to overloads during their use and the porosities linked to the LPBF process are preferential places for crack initiation. In order to increase the lifetime of these parts, an innovative approach is to think about the mechanisms called "self-healing" in literature.
The objective of my thesis is to develop a new high-strength aluminium alloy that can be produced by LPBF and that is capable of “self-healing” during Hot Isostatic Pressing (HIP). The AlMg14 alloy is capable of self-healing due to the presence of a eutectic phase that melts under heat treatment. Nevertheless, under a simple heat treatment, the characteristic size repaired is of the order of 1 µm, much smaller than the LPBF-related defects causing fatigue crack initiation (~50 µm). Thus, the addition of pressure will allow the cracks to be sealed prior to welding by melting the eutectic phase.
Another limitation of this AlMg14 alloy is its very low mechanical strength (~150 MPa). Therefore, alloying elements will be added (e.g. Zn, Sc, Zr) in order to create hardening precipitates. These additions can also allow the control of hot cracking.
The new alloy as well as reference alloys (no repair/no pressure) will be statically and cyclically loaded using macroscopic and in-situ tests to reveal the underlying failure mechanisms.

Recent publications

See complete list of publications

Journal Articles

1. Dimov, Nicolas; Weisz-Patrault, Daniel; Tanguy, Alexandre; Sapanathan, Thaneshan; Benoist, Julien; Charkaluk, Eric; Simar, Aude. Strain and damage analysis using high resolution digital image correlation in the stir zone of an AA6061-AA7075 dissimilar friction stir weld. In: Materials Today Communications, Vol. 34, p. 105359 (2023). doi:10.1016/j.mtcomm.2023.105359. http://hdl.handle.net/2078.1/269843

2. Song, Lubin; Yuan, Shulin; Zhao, Lv; Zhu, Yaxin; Liang, Shuang; Huang, Minsheng; Simar, Aude; Li, Zhenhuan. Deciphering phase stress partition and its correlation to mechanical anisotropy of laser powder bed fusion AlSi10Mg. In: Additive Manufacturing, Vol. 71, p. 103594 (2023). doi:10.1016/j.addma.2023.103594. http://hdl.handle.net/2078.1/274703

3. Gheysen, Julie; Tingaud, David; Villanova, Julie; Hocini, Azziz; Simar, Aude. Exceptional fatigue life and ductility of new liquid healing hot isostatic pressing especially tailored for additive manufactured aluminum alloys. In: Scripta Materialia, Vol. 233, p. 115512 (2023). doi:10.1016/j.scriptamat.2023.115512. http://hdl.handle.net/2078.1/274418

4. Han, Sutao; Lezaack, Matthieu Baudouin; Pyka, Grzegorz; Gomes Affonseca Netto, Nelson; Simar, Aude; Wahab, Magd Abdel; Hannard, Florent. On the Competition between Intergranular and Transgranular Failure within 7 Al Alloys with Tailored Microstructures. In: Materials, Vol. 16, no.10, p. 3770 (2023). doi:10.3390/ma16103770. http://hdl.handle.net/2078.1/274986

5. Krishnamurthy, Sanjay Channappa; Arseenko, Mariia; Kashiwar, Ankush; Dufour, Philippe; Marchal, Yves; Delahaye, Jocelyn; Idrissi, Hosni; Pardoen, Thomas; Mertens, Anne; Simar, Aude. Controlled precipitation in a new Al-Mg-Sc alloy for enhanced corrosion behavior while maintaining the mechanical performance. In: Materials Characterization, Vol. 200, p. 112886 (2023). doi:10.1016/j.matchar.2023.112886. http://hdl.handle.net/2078.1/274100

6. Gheysen, Julie; Kashiwar, Ankush; Idrissi, Hosni; Villanova, Julie; Simar, Aude. Suppressing hydrogen blistering in a magnesium-rich healable laser powder bed fusion aluminum alloy analyzed by in-situ high resolution techniques. In: Materials & Design, Vol. 231, p. 112024 (2023). doi:10.1016/j.matdes.2023.112024. http://hdl.handle.net/2078.1/275034

7. Heidarzadeh, Akbar; Mohammadzadeh, Roghayeh; Jafarian, Hamid Reza; Pruncu, Catalin; Simar, Aude. Role of geometrically necessary dislocations on mechanical properties of friction stir welded single-phase copper with medium stacking fault energy. In: Journal of Materials Research and Technology, Vol. 16, p. 194-200 (2022). doi:10.1016/j.jmrt.2021.11.162. http://hdl.handle.net/2078.1/254558

8. Avettand-Fènoël, M.-N.; Gomes Affonseca Netto, Nelson; Simar, Aude; Marinova, M.; Taillard, R. Design of a metallic glass dispersion in pure copper by friction stir processing. In: Journal of Alloys and Compounds, Vol. 907, p. 164522 (2022). doi:10.1016/j.jallcom.2022.164522. http://hdl.handle.net/2078.1/259509

9. Santos Macías, Juan Guillermo; Zhao, Lv; Tingaud, David; Bacroix, Brigitte; Pyka, Grzegorz; van der Rest, Camille; Ryelandt, Laurence; Simar, Aude. Hot isostatic pressing of laser powder bed fusion AlSi10Mg: parameter identification and mechanical properties. In: Journal of Materials Science, Vol. Special issue on Additive Manufacturing (2022). doi:10.1007/s10853-022-07027-9. http://hdl.handle.net/2078.1/259038

10. Song, Lubin; Zhao, Lv; Ding, Lipeng; Zhu, Yaxin; Huang, Minsheng; Simar, Aude; Li, Zhenhuan. Microstructure and loading direction dependent hardening and damage behavior of laser powder bed fusion AlSi10Mg. In: Materials Science and Engineering: A, Vol. 832, p. 142484 (2022). doi:10.1016/j.msea.2021.142484. http://hdl.handle.net/2078.1/254707

Patents

1. Jacques, Pascal; van der Rest, Camille; Simar, Aude. Method for Welding at least two layers. http://hdl.handle.net/2078.1/135184 http://hdl.handle.net/2078.1/135184

2. Jacques, Pascal; Simar, Aude; van der Rest, Camille; Matagne, Ernest; Roy, Geoffrey; Shmitz, Alain. Thermoelectric conversion module and method for making it. http://hdl.handle.net/2078.1/135212 http://hdl.handle.net/2078.1/135212

Conference Papers

1. De Raedemacker, Sophie; Gheysen, Julie; Pyka, Grzegorz; Hannard, Florent; Winiarski, Bartłomiej; Tingaud, David; Hocini, Azziz; Villanova, Julie; Smith, Albert; Donoghue, Jack; Simar, Aude. Design of a new high strength liquid assisted healable AlMg alloy produced by Laser Powder Bed Fusion (LPBF). 2023 xxx. http://hdl.handle.net/2078.1/267833

2. Krishnamurthy, Sanjay Channappa; Simar, Aude. Process parameter influence and characterization of spot friction melt bonded titanium and aluminium alloy. 2023 xxx. http://hdl.handle.net/2078.1/271853

3. Nothomb, Nicolas; Longin, Julien; Rodriguez-Barber, Ignacio; Pérez Prado, Maria Teresa; Avettand-Fénoël, Marie-Noeëlle; Simar, Aude. Fully dense Al7075 produced by laser powder bed fusion (L-PBF) undergoing a tailored innovative heat treatment showing high tensile properties and interesting fatigue crack growth behaviour. In: BDFM-2023_Book of abstracts, 2023, p. Poster No. 10 xxx. http://hdl.handle.net/2078.1/275121

4. De Raedemacker, Sophie; Gheysen, Julie; Pyka, Grzegorz; Hannard, Florent; Winiarski, Bartłomiej; Tingaud, David; Hocini, Azziz; Villanova, Julie; Smith, Albert; Donoghue, Jack; Jiang, Lin; Simar, Aude. Development of a high strength liquid assisted healable AlMg alloy with Zr addition produced by additive manufacturing. 2023 xxx. http://hdl.handle.net/2078.1/273253

5. De Raedemacker, Sophie; Gheysen, Julie; Pyka, Grzegorz; Hannard, Florent; Winiarski, Bartlomiej; Tingaud, David; Hocini, Azziz; Villanova, Julie; Smith, Albert; Donoghue, Jack; Jiang, Lin; Simar, Aude. Development of a new healable aluminium alloy produced by Laser Powder Bed Fusion (LPBF) and improvement of its strength through strengthening element addition. In: BDFM-2023_Book of abstracts, 2023, p. Poster No. 15 xxx. http://hdl.handle.net/2078.1/275123

6. Simar, Aude. Healing damage in aluminium alloys. 2023 xxx. http://hdl.handle.net/2078.1/274994

7. Santos Macias, Juan Guillermo; Elangeswaran, Chola; Van Hooreweder, Brecht; Buffière, Jean-Yves; Bacroix, Brigitte; Tingaud, David; Pyka, Grzegorz; Zhao, Lv; Simar, Aude. Fatigue resistance improvement of laser powder bed fusion AlSi10Mg by post-processing. 2022 xxx. http://hdl.handle.net/2078.1/259623

8. Voet, Vincent; De Fruytier, Christophe; Simar, Aude; Pardoen, Thomas. Thermal ageing of electronic component solder joints for space applications: a combined finite element and deep learning approach. 2022 xxx. http://hdl.handle.net/2078.1/259627

9. Gomes Affonseca Netto, Nelson; Zhao, Lv; Charkaluk, Eric; Simar, Aude. Enhancing fatigue crack growth resistance of high strength aluminum alloys reinforced by shape memory alloy. 2022 xxx. http://hdl.handle.net/2078.1/259626

10. Nothomb, Nicolas; van der Rest, Camille; Santos Macias, Juan Guillermo; Zhao, Lv; Delmée, Maxime; Simar, Aude. Fatigue life improvement of high strength aluminium alloys produced by laser powder bed fusion (L-PBF). 2022 xxx. http://hdl.handle.net/2078.1/263164

Book Chapters

1. Simar, Aude; Poncelet, Olivier; Desrayaud, Christophe; Eimer, Eloise. Les microstructures des alliages d'aluminium. In: La fabrication additive des alliages métalliques 2 - microstructures, post-traitements et propriétés d'usage , xxx, 2022, p. 79-92. 9781789480559. xxx xxx. http://hdl.handle.net/2078.1/259584

2. Arseenko, Mariia; Gheysen, Julie; Hannard, Florent; Nothomb, Nicolas; Simar, Aude. Self-Healing in Metal-Based Systems. In: Engineering Materials and Processes : Self-Healing Construction Materials , Springer, 2022, p. 43-78. 9783030868796. xxx xxx. doi:10.1007/978-3-030-86880-2_3. http://hdl.handle.net/2078.1/259310

3. Simar, Aude; Avettand-Fenoël, Marie-Noëlle. Friction Stir Processing for Architectured Materials. In: Architectured Materials in Nature and Engineering (Springer Series in Materials Science; xxx), Springer, Cham, 2019, p. 195-229. 978-3-030-11941-6. xxx xxx. doi:10.1007/978-3-030-11942-3_7. http://hdl.handle.net/2078.1/214932

Dissertations

1. Simar, Aude. A multiscale multiphysics investigation of aluminum friction stir welds : from thermal modelling to mechanical properties through precipitation evolution and hardening/, prom. : Pardoen, Thomas ; de Meester, Bruno, 2006-07-17. http://hdl.handle.net/2078.1/5203