Laboratoire de mécanique des solides
Laboratoire de mécanique des solides
Laboratoire de mécanique des solides

Publications

Publications

2024

  • Numéro spécial hommage à Pierre Bérest
    • Blanco-Martín Laura
    • Brouard Benoît
    • Constantinescu Andréi
    • Cosenza Philippe
    • Dimanov Alexandre
    • Sulem Jean
    Revue française de Géotechnique, edp sciences, 2024 (177), pp.E1. Ce numéro spécial de la <i>Revue Française de Géotechnique</i> constitue pro parte les actes de la conférence internationale «&nbsp;Underground Storage and Geoenergies: Solutions for Energy Transition?&nbsp;» qui s’est tenue les&nbsp;14 et 15&nbsp;juin 2023 à l’École Polytechnique&nbsp;(X). Cette conférence internationale labellisée par le centre interdisciplinaire Energy4Climate (E4C) de l’Institut Polytechnique de Paris et l’École des Ponts ParisTech a été organisée sous l’impulsion du CFMR, du Laboratoire de Mécanique des Solides de l’X et du centre de Géosciences de l’École des Mines de Paris pour rendre hommage à une grande figure de la mécanique des roches&nbsp;: Pierre Bérest. Cette conférence internationale et donc ce numéro spécial permettent de dresser un état des lieux des recherches sur le stockage géologique et plus particulièrement des problématiques de mécanique des roches associées au stockage souterrain. Cet état des lieux fait évidemment la «&nbsp;part belle&nbsp;» à la mécanique du sel gemme qui fascinait tant Pierre Bérest. Ainsi les trois premiers articles de ce numéro spécial concernent directement le comportement du sel gemme et des cavités salines. Dans le premier article, Blanco-Martín, Jiménez-Camargo, Jaworowicz, Gharbi, Dimanov, Bornert et Brouard abordent la difficile caractérisation du comportement en fluage sous faible déviateur (typiquement inférieur à 5 MPa) du sel gemme. Les auteurs exploitent une idée lumineuse de Pierre Bérest&nbsp;: l’utilisation de galeries reculées de mines souterraines soumises à des conditions de température et d’hygrométrie extrêmement stables pour y mener des essais de fluage de longue durée sous faible contrainte. Dans le deuxième article de cette série «&nbsp;salifère&nbsp;», Karimi-Jafari et Brouard s’intéressent notamment au fluage «&nbsp;inverse&nbsp;», une caractéristique curieuse et très particulière du comportement mécanique transitoire du sel gemme. Ils soulignent également la nécessité d’intégrer la redistribution des contraintes induite par le comportement viscoplastique de la roche dans l’étude de la stabilité des cavités salines. En utilisant une modélisation thermomécanique couplée, l’article de Djizanne, Brouard, Hévin et Lekoko explore l’intégrité structurelle d’une cavité saline soumise à des conditions de chargement extrêmes sur une longue période. Il apporte ainsi des informations pour le dimensionnement, l’exploitation et la maintenance des futurs sites de stockage souterrain d’hydrogène gazeux. D’un point de vue plus fondamental, l’article de Gratier présente un panorama très complet sur le rôle du mécanisme de dissolution-cristallisation dans les processus de fluage et de cicatrisation des failles et plus largement dans la déformation géologique de la croûte terrestre. Il souligne l’intuition qu’avait Pierre Bérest sur l’importance d’un tel micro-mécanisme de déformation dans le comportement en fluage du sel gemme aux faibles déviateurs. Le dernier article, de David, de ce numéro témoigne de l’intérêt qu’avait Pierre Bérest pour les développements expérimentaux originaux de mécanique des roches. Il présente un nouveau dispositif expérimental versatile pour la mesure de la ténacité en mode&nbsp;I des roches. La conférence hommage à Pierre Bérest et donc ce numéro spécial n’auraient pas vu le jour sans le soutien précieux du centre interdisciplinaire Energy4Climate (E4C) et surtout de son directeur Philippe Drobinski, qui a accueilli avec enthousiasme l’ensemble de ces initiatives. Qu’il en soit ici remercié. Nous tenons également à remercier l’ensemble des auteurs pour leurs contributions de qualité et pour nous avoir partagé ainsi les passions scientifiques de Pierre Bérest. (10.1051/geotech/2024021)
    DOI : 10.1051/geotech/2024021
  • Microstructure mastering and fatigue behavior of duplex stainless steel obtained with laser powder bed fusion
    • Piras Maxime
    • Hor Anis
    • Charkaluk Eric
    , 2024, pp.290-299. Microstructure and mechanical behavior of duplex stainless steels (DSS) are well known when elaborated with conventional processes. Nowadays, many studies aimed to characterize this material for additive manufacturing (AM) processes like laser powder bed fusion (LPBF) [1], [2]. The as-built LPBF microstructure of this alloy is totally ferritic [1]. Heat treatments are therefore necessary to recover the duplex microstructure. These heat treatments need to be optimized. The effects of annealing heat treatments on the microstructure and mechanical behavior of DSS are now known [2], but the consequences on its fatigue strength need to be explored. In this study, firstly, the duplex microstructure will be controlled by heat treatments to obtain austenitic phase with different grain morphology. Then, the influence of microstructure on tensile high cycle fatigue behavior will be investigated. As a result, a microstructure with coarser austenite grains has no effect on fatigue behavior compared to the fully ferritic As-built material whereas the finer microstructure allows an improvement. Even if there is austenite phase improving the material ductility, fatigue damage initiation is always due to pore defects. (10.21741/9781644903131-33)
    DOI : 10.21741/9781644903131-33
  • Well-posedness and potential-based formulation for the propagation of hydro-acoustic waves and tsunamis
    • Dubois Juliette
    • Imperiale Sébastien
    • Mangeney Anne
    • Sainte-Marie Jacques
    ESAIM: Mathematical Modelling and Numerical Analysis, Société de Mathématiques Appliquées et Industrielles (SMAI) / EDP, 2024. We study a linear model for the propagation of hydro-acoustic waves and tsunami in a stratified free-surface ocean. A formulation was previously obtained by linearizing the compressible Euler equations. The new formulation is obtained by studying the functional spaces and operators associated to the model. The mathematical study of this new formulation is easier and the discretization is also more efficient than for the previous formulation. We prove that both formulations are well posed and show that the solution to the first formulation can be obtained from the solution to the second. Finally, the formulations are discretized using a spectral element method, and we simulate tsunamis generation from submarine earthquakes and landslides. (10.1051/m2an/2024076)
    DOI : 10.1051/m2an/2024076
  • Using a micro-device with a deformable ceiling to probe stiffness heterogeneities within 3D cell aggregates
    • Jain Shreyansh
    • Belkadi Hiba
    • Michaut Arthur
    • Sart Sébastien
    • Gros Jérôme
    • Genet Martin
    • Baroud Charles N
    Biofabrication, IOP Publishing, 2024, 16 (3), pp.035010. Recent advances in the field of mechanobiology have led to the development of methods to characterise single-cell or monolayer mechanical properties and link them to their functional behaviour. However, there remains a strong need to establish this link for three-dimensional (3D) multicellular aggregates, which better mimic tissue function. Here we present a platform to actuate and observe many such aggregates within one deformable micro-device. The platform consists of a single polydimethylsiloxane piece cast on a 3D-printed mould and bonded to a glass slide or coverslip. It consists of a chamber containing cell spheroids, which is adjacent to air cavities that are fluidically independent. Controlling the air pressure in these air cavities leads to a vertical displacement of the chamber’s ceiling. The device can be used in static or dynamic modes over time scales of seconds to hours, with displacement amplitudes from a few µ m to several tens of microns. Further, we show how the compression protocols can be used to obtain measurements of stiffness heterogeneities within individual co-culture spheroids, by comparing image correlations of spheroids at different levels of compression with finite element simulations. The labelling of the cells and their cytoskeleton is combined with image correlation methods to relate the structure of the co-culture spheroid with its mechanical properties at different locations. The device is compatible with various microscopy techniques, including confocal microscopy, which can be used to observe the displacements and rearrangements of single cells and neighbourhoods within the aggregate. The complete experimental and imaging platform can now be used to provide multi-scale measurements that link single-cell behaviour with the global mechanical response of the aggregates. (10.1088/1758-5090/ad30c7)
    DOI : 10.1088/1758-5090/ad30c7
  • Multi-scale experimental deformation and damage initiation of clay-rich rocks
    • Lusseyran Matthieu
    • Tanguy Alexandre
    • Bonnelye Audrey
    • Dimanov Alexandre
    • Fortin Jerome
    , 2024. Understanding the damage processes in clay-bearing rocks is a decisive factor in geological engineering, and for instance considering nuclear waste deep geological repositories. But, more generally they may also contribute to localized deformation, and thus the rupture of fault gauges in seismic zones. However, owing to their complex mineralogy, multiscale microstructures and anisotropy, the mechanisms of clay-rich rock damage and their chronology are not yet well understood. Here we focus on the impact of micro-damage on ultrasonic wave propagation velocity, which is confronted with the corresponding full deformation fields calculated by digital image correlation (DIC). The aim is to associate the acoustic signature with the active deformation mechanisms identified by DIC. To this end, an integrated experimental approach is proposed to characterize localization and to identify the related deformation micro-mechanisms during uniaxial compression of natural clayey rock samples (Tournemire shales) with two simultaneous measurements: (i) the evolution of P-wave velocity within the sample by active acoustics, (ii) the development of the 2D mechanical full field by digital image correlation. Both experimental techniques are well known, but the innovation of our approach is to combine simultaneously both measurements. Deformation localization is a multiscale problem, which obviously occurs at the sample scale, but also at the fines scales of the microstructure. Therefore, we developed two different experimental setups. On the one hand, during uniaxial compression with a standard MTS loading frame the macro-scale localization patterns are characterized by optical observations, which image resolution is well suited to the cm sample scale (sample diameter: 3.6 cm and double in length). On the other hand, in order to characterize the initiation of micro-damage at the microstructure scale of the composite type of rock, the same loading protocol is reproduced (while keeping the acoustic diagnosis) on smaller scale mm-sized specimens (sample diameter : 8 mm, double in length), using a home-designed miniature loading frame fit for an environmental scanning electron microscope (ESEM). The latter analysis is carried out under controlled relative humidity of RH = 80%, hence preventing the samples to dry out due to the high vacuum Damage processes measured by digital image correlation (DIC) are usually represented over time as a series of deformation maps. This method is well suited to identify major damage events (macro-cracks). However, these highly localized events have little impacts on acoustic wave propagation velocity, unlike densely distributed micro-cracks. Therefore, we propose a method for analyzing the same data, to our knowledge original, revealing the temporal evolution of all deformation scales. A single map summarizes the entire temporal process with deformation classes as x-axis and time as y-axis. We call this representation the “Chronogram of Strain Distribution" (CSD). This projection has a number of advantages: (i) it removes micro-deformations from the ground noise of DIC; (ii) it explicitly links volumetric integration, inherent to Vp wave velocity measurement, to the full deformation field; (iii) it keeps the chronology of the different deformation process.
  • Rock salt creep: a cross-check test to cover the full relevant range of deviatoric stresses
    • Blanco-Martín Laura
    • Jiménez-Camargo Jubier
    • Jaworowicz Jerzy
    • Gharbi Hakim
    • Dimanov Alexandre
    • Bornert Michel
    • Brouard Benoît
    Revue française de Géotechnique, edp sciences, 2024 (177). The time-dependent response of rock salt has been mainly investigated using confined creep tests covering a differential stress range between 5 and 20 MPa. In recent years, efforts have been made to investigate the range 0.1–4.5 MPa, using dead-end drifts in underground mines to take advantage of the very stable ambient conditions (temperature, relative humidity). Up to now, the combination of experimental data in the two ranges is difficult because of the use of different salt facies, sample preparation methods, test temperatures and experimental conditions ( e.g. , confined vs. unconfined tests, scale of measurements). In this work, we conduct two long-term creep tests on two natural salt samples from the same origin and prepared using the same protocol. The thermo-mechanical loading path is the same for the two tests, with only a small difference in the lateral load. One test is performed in a remote drift in a salt mine and the other test is performed in a climatic chamber in the laboratory. The comparison of the results is consistent, allowing to investigate a large range of deviatoric stresses by combining results in the two facilities. The final goal of this approach is to reduce stress extrapolation by investigating the whole deviatoric range that is relevant for underground operations. Next steps include investigating in more detail the effect of intergranular fluids, testing different temperatures and performing confined tests in the mine. (10.1051/geotech/2024017)
    DOI : 10.1051/geotech/2024017
  • Coupling Phase Field Crystal and Field Dislocation Mechanics for a consistent description of dislocation structure and elasticity
    • Upadhyay Manas V
    • Viñals Jorge
    , 2024. This work addresses differences in predicted elastic fields created by dislocations either by the Phase Field Crystal (PFC) model, or by static Field Dislocation Mechanics (FDM). The PFC order parameter describes the topological content of the lattice, but it fails to correctly capture the elastic distortion. In contrast, static FDM correctly captures the latter but requires input about defect cores. The case of a dislocation dipole in two dimensional, isotropic, elastic medium is studied, and a weak coupling is introduced between the two models. The PFC model produces compact and stable dislocation cores, free of any singularity, i.e., diffuse. The PFC predicted dislocation density field (a measure of the topological defect content) is used as the source (input) for the static FDM problem. This coupling allows a critical analysis of the relative role played by configurational (from PFC) and elastic (from static FDM) fields in the theory, and of the consequences of the lack of elastic relaxation in the diffusive evolution of the PFC order parameter.
  • Deformation of Aluminum Investigated by Digital Image Correlation: Evidence of Simultaneous Crystal Slip and Grain Boundary Sliding
    • Dimanov A.
    • El Sabbagh A.
    • Raphanel J.
    • Bornert M.
    • LE Thien-Nga
    • Hallais S.
    • Tanguy A.
    Metallurgical and Materials Transactions A, Springer Verlag/ASM International, 2024, 55 (6), pp.1814-1835. We investigate the multiscale micromechanical behavior of nearly pure polycrystalline aluminum exhibiting randomly oriented coarse grains (ca. 300 m in size) between room temperature and 400°C. We present results from in situ mechanical testing obtained through scanning electron microscopy and full-field strain measurements by digital image correlation (DIC) during uniaxial compression, with controlled displacement rate. Direct observation of the process of developing strain heterogeneities allows for identification of the active mechanisms, characterization of their interactions and quantification of their respective contributions to the overall strain. The full-field strain measurements were carried out, from the sample scale, to the scales of the aggregate of grains, and finally the single grain. DIC analysis was performed thanks to specific surface marking patterns obtained by electron microlithography appropriate for the different scales of interest. The strain localization patterns showed dominant crystal plasticity. Except at room temperature, we always observed simultaneous and continuous activity of grain boundary sliding, whose relative contribution increased with temperature. We suggest that for coarse-grained microstructures grain boundary sliding acts as a complementary mechanism for the accommodation of local plastic incompatibilities inherent to the anisotropy of crystal plasticity. (10.1007/s11661-024-07349-0)
    DOI : 10.1007/s11661-024-07349-0
  • Effect of the elevated temperature on the wear behavior of Laser Metal Deposition IN718 repairs
    • Zurcher Théo
    • Bouvard Gaëtan
    • Abry Jean-Christophe
    • Fridrici Vincent
    • Charkaluk Éric
    Tribology International, Elsevier, 2024, 192, pp.109276. IN718, a nickel-based superalloy popular in aerospace, has good high-temperature mechanics/corrosion resistance. Laser Metal Deposition (LMD) repairs using IN718 are extensively explored, yet few studies delve into their tribological aspects. This research examines post-treated IN718 coatings, mimicking rapid repairs, investigating their high-temperature tribological behavior. Samples underwent tribological tests at diverse loads and temperatures. Results show the scanning strategy does not impact the wear behavior. At elevated temperatures, a glaze layer forms in the contact zone, impacting lubrication and surface protection based on its uniformity. Despite its advantageous lubricating ability, at 400°C and 50 N force, the oxidized debris layer lacks mechanical stability. IN718 LMD repairs manifest enhanced high-temperature wear resistance compared to ambient conditions, attributed to the glaze layer. (10.1016/j.triboint.2024.109276)
    DOI : 10.1016/j.triboint.2024.109276
  • In-situ localization of damage in a Zn-Al-Mg coating deposited on steel by continuous hot-dip galvanizing
    • Chaieb Houssem Eddine
    • Maurel Vincent
    • Ammar K
    • Forest Samuel
    • Tanguy Alexandre
    • Héripré Eva
    • Nozahic Franck
    • Mataigne Jean-Michel
    • de Strycker Joost
    Scripta Materialia, Elsevier, 2024, 243, pp.115960. (10.1016/j.scriptamat.2023.115960)
    DOI : 10.1016/j.scriptamat.2023.115960
  • Sharp-Interface Cohesive Fracture Models with Consistent Bulk Energies: Numerical Investigations
    • Rodella A
    • Marigo J.-J
    • Maurini C
    • Vidoli S
    , 2025. We investigate sharp-interface cohesive fracture models formulated as energy minimization problems. We argue that models with arbitrary cohesive interfaces are incompatible with linear bulk elasticity, in the sense that they cannot feature solutions in the form of a regular crack with a simple tip. To this end, we provide analytical and numerical solutions for a model problem consisting of a single straight crack under mode-III loading, where we show that the stress magnitude exceeds the cohesive yield threshold in a finite region around the crack tip. Our findings are consistent with the unavailability of existence results for such models, related to the lack of lower semicontinuity of the associated variational problem. In the mathematical literature, lower semicontinuity and existence of solutions is recovered by introducing a relaxed functional combining the cohesive surface energy on the crack set with a bulk behavior comparable to perfect plasticity, where the bulk strength is determined by the maximal allowable traction of the cohesive law. The relaxed energy provides a homogenised macroscopic model of the possible microscopic structuring of a dense distribution of cracks with vanishing displacement jumps. We report numerical simulations in antiplane shear that illustrate that the relaxed model admits an equilibrium solution in the form of straight cracks that capture both crack nucleation and propagation. Cracks emerging from pre-existing flaws and notches exhibit a smooth transition from classical crack tip plasticity solutions near the notch to a propagating cohesive crack accompanied by an elongated zone around the tip where the nonlinear bulk behavior is active and the stress is constant. We discuss how these observations can inform the development of mathematically consistent coupled models with a minimal number of constitutive parameters, highlighting the inconsistencies observed when arbitrarily combining models with different surface and bulk strengths.
  • An implicit–explicit time discretization for elastic wave propagation problems in plates
    • Methenni Hajer
    • Imperiale Alexandre
    • Imperiale Sébastien
    International Journal for Numerical Methods in Engineering, Wiley, 2024, 125, pp.e7393. We propose a new implicit–explicit scheme to address the challenge of modeling wave propagation within thin structures using the time‐domain finite element method. Compared to standard explicit schemes, our approach renders a time marching algorithm with a time step independent of the plate thickness and its associated discretization parameters (mesh step and order of approximation). Relying on the standard three dimensional elastodynamics equations, our strategy can be applied to any type of material, either isotropic or anisotropic, with or without discontinuities in the thickness direction. Upon the assumption of an extruded mesh of the plate‐like geometry, we show that the linear system to be solved at each time step is partially lumped thus efficiently treated. We provide numerical evidence of an adequate convergence behavior, similar to a reference solution obtained using the well‐known leapfrog scheme. Further numerical investigations show significant speed up factors compared to the same reference scheme, proving the efficiency of our approach for the configurations of interest. (10.1002/nme.7393)
    DOI : 10.1002/nme.7393
  • Introduction aux équations aux dérivées partielles hyperboliques et à leur approximation numérique
    • Fliss Sonia
    • Bonnet-Ben Dhia Anne-Sophie
    • Joly Patrick
    • Moireau Philippe
    , 2024.
  • Multi-scale Modeling of the Lung Parenchyma
    • Manoochehrtayebi Mahdi
    , 2024. Idiopathic pulmonary fibrosis (IPF), a type of interstitial lung disease that causes thickening and stiffening of particular alveoli septa, is poorly diagnosed, prognosed, and treated. From the clinical point of view, multiple investigations are required for a precise diagnosis, which is time-consuming with respect to the life expectancy of the patient. IPF targets the structure of the lung and its geometrical and mechanical properties, which are connected to the organ-scale behavior of the lung and respiratory problems. Understanding such a connection can be addressed through mechanical modeling, which can quantify the primary clinical data, namely CT scans, and return a relatively quick diagnosis. In this work, we have proposed a multi-scale modeling of the lung parenchyma through a mechanical approach. A general micro-poro-mechanical model is proposed to simulate the behavior of the compressible and incompressible porous materials at the microscopic scale and link the microscopic mechanical and morphological features to the macroscopic scale behavior. Such a model is defined based on a periodic microstructure with different choices that undergo finite strains. Moreover, the micro-poro-mechanical model can show not only the microscopic stress and strain distribution under various loadings such as macroscopic stress, macroscopic strain, and fluid pressure but also their average manifestations at the macroscopic scale. This model is first compared to the macro-poromechanics to investigate the relevance of the macroscopic approach to the microscopic ones. Second, the model is updated to reproduce the experimental behavior of the lung parenchyma. Surface tension, as a microscopic physiological phenomenon on the alveolar walls, which is a response for maintaining stability and lung parenchyma in the presence of fluid pressure, is encountered in the model. Moreover, the parameters of the model are identified with some existing experimental data.
  • A unified theoretical modeling framework for soft and hard magnetorheological elastomers
    • Danas Kostas
    , 2024, 610, pp.59-139. These notes put together a number of theoretical and numerical models and results obtained for magnetically soft and hard magnetorheological elastomers, denoted as s-MREs and h-MREs, respectively over the last five years in our group. We present in a unified manner both sand h-MREs. In particular, we regard MREs, in the general case, as magnetically dissipative nonlinear elastic composite materials comprising a mechanically-soft, non-magnetic elastomeric matrix in which mechanically-rigid, magnetically-dissipative particles are embedded isotropically and randomly. The proposed incremental variational frameworks are general enough to deal with more complex microstructures such as particle-chains or others that do not yet exist in the lab. More importantly, we propose homogenization-guided, analytical, explicit models that are consistent as one moves from the dissipative h-MREs to the purely energetic s-MREs. In parallel, we propose numerical frameworks allowing to simulate a very wide variety of microstructures and boundary value problems in magneto-mechanics. (10.1007/978-3-031-48351-6_3)
    DOI : 10.1007/978-3-031-48351-6_3
  • The effect of echoes interference on phonon attenuation in a nanophononic membrane
    • Hadi Mohammad
    • Luo Haoming
    • Pailhès Stéphane
    • Tanguy Anne
    • Gravouil Anthony
    • Capotondi Flavio
    • de Angelis Dario
    • Fainozzi Danny
    • Foglia Laura
    • Mincigrucci Riccardo
    • Paltanin Ettore
    • Pedersoli Emanuele
    • Pelli-Cresi Jacopo
    • Bencivenga Filippo
    • Giordano Valentina
    Nature Communications, Nature Publishing Group, 2024, 15 (1), pp.1317. Abstract Nanophononic materials are characterized by a periodic nanostructuration, which may lead to coherent scattering of phonons, enabling interference and resulting in modified phonon dispersions. We have used the extreme ultraviolet transient grating technique to measure phonon frequencies and lifetimes in a low-roughness nanoporous phononic membrane of SiN at wavelengths between 50 and 100 nm, comparable to the nanostructure lengthscale. Surprisingly, phonon frequencies are only slightly modified upon nanostructuration, while phonon lifetime is strongly reduced. Finite element calculations indicate that this is due to coherent phonon interference, which becomes dominant for wavelengths between ~ half and twice the inter-pores distance. Despite this, vibrational energy transport is ensured through an energy flow among the coherent modes created by reflections. This interference of phonon echos from periodic interfaces is likely another aspect of the mutual coherence effects recently highlighted in amorphous and complex crystalline materials and, in this context, could be used to tailor transport properties of nanostructured materials. (10.1038/s41467-024-45571-x)
    DOI : 10.1038/s41467-024-45571-x
  • Comportement en fissuration d’une colle thermoplastique pour application de joints de pales éoliennes
    • Coq Arnaud
    , 2024. Cette thèse aborde l'étude du comportement en fissuration d'un adhésif thermoplastique acrylique, développé dans le but de remplacer les adhésifs thermodurcissables de type époxy habituellement utilisés dans le collage de pâles éoliennes. Le travail s'inscrit dans une démarche globale de substitution des polymères thermodurcissables par des polymères thermoplastiques, en raison de leur capacité à être recyclés. Cependant une telle démarche vertueuse d’un point de vue environnemental doit s’appuyer sur une validation de la tenue mécanique des nouveaux polymères de substitution. Dans ce contexte, l’objectif du travail développé ici a été de caractériser expérimentalement la fissuration de la colle en masse et d’en proposer une modélisation numérique pour extraire un critère objectif de fissuration en mode d’ouverture. La démarche scientifique s’articule donc autour de deux axes principaux. Premièrement, une étude expérimentale a été menée pour déterminer le comportement de la colle et sa fissuration en mode d’ouverture par des essais DCDC (Double Cantilever Beam Test) et SENB (Single Edge Notch Bending) correspondant à des états de chargements différents. Deuxièmement, une modélisation numérique a été mise en place pour simuler l'endommagement de la colle en utilisant un comportement élasto-plastique. Deux approches d'endommagement ont été envisagées, l'une basée sur la théorie du champ de phase et l'autre sur les éléments cohésifs. Les résultats obtenus grâce à ces deux approches ont été confrontées aux résultats expérimentaux afin de déterminer les propriétés de fissuration du matériau. Cette recherche permet d'évaluer quantitativement la fissuration de la colle étudiée et plus largement d'étudier la caractérisation de la fissuration des polymères amorphes à l’état vitreux.
  • Preparative supercritical fluid chromatography as green purification methodology
    • Peyrin Eric
    • Lipka Emmanuelle
    Trends in Analytical Chemistry, Elsevier, 2024, 171, pp.117505. <div xmlns="http://www.tei-c.org/ns/1.0"><p>In this work, a tentative of answer is given to the question: to which extent preparative scale supercritical fluid chromatography can be considered as a green method. In the introduction, we present how supercritical liquid chromatography theoretically meets the six concepts of green analytical chemistry. Then, a first part is devoted to the greenness assessment indicators of the chomatographic methods involved. The metrics are defined together with some applications of those calculations. A second part decribes the recent evolutions aiming at lowering the environmental impact of preparative separation. Firstly through instrumentation improvements, such as computer-assisted method development, performances enhancement or using supercritical fluid-based processes. And secondly through the implementation of greener mobile phases, involving either the addition of water, the use of azeotropic ethanol or chaotropic agents. The review covers the frame of 2018 to 2022, but seminal papers are also given when needed.</p></div> (10.1016/j.trac.2023.117505)
    DOI : 10.1016/j.trac.2023.117505
  • From emissions to resources: mitigating the critical raw material supply chain vulnerability of renewable energy technologies
    • Mertens Jan
    • Dewulf Jo
    • Breyer Christian
    • Belmans Ronnie
    • Gendron Corinne
    • Geoffron Patrice
    • Goossens Luc
    • Fischer Carolyn
    • Du Fornel Elodie
    • Hayhoe Katharine
    • Hirose Katsu
    • Le Cadre-Loret Elodie
    • Lester Richard
    • Maigné Fanny
    • Maitournam Habibou
    • de Miranda Paulo Emilio Valadão
    • Verwee Peter
    • Sala Olivier
    • Webber Michael
    • Debackere Koenraad
    Mineral Economics, Springer, 2024, 37 (3), pp.669-676. The massive deployment of clean energy technologies plays a vital role in the strategy to attain carbon neutrality by 2050 and allow subsequent negative CO2 emissions in order to achieve our climate goals. An emerging challenge, known as ‘From Emissions to Resources,’ highlights the signifcant increase in demand for critical raw materials (CRMs) in clean energy technologies. Despite the presence of ample geological reserves, ensuring sustainable access to these materials is crucial for the successful transition to clean energy, taking into account the environmental and social impacts. The commentary centers on four renewable energy technologies namely solar photovoltaics, wind turbines, Li-ion batteries, and water electrolysers. Four pathways for mitigation are quantitatively examined to assess their potential in reducing the vulnerability of the CRM supply chain for these four clean energy technologies: (i) Enhancing material efciency, (ii) employing substitutivity strategies, (iii) exploring recycling prospects, and (iv) promoting relocalisation initiatives. It is important to note that no single mitigation lever can completely eliminate the risk of CRM supply, rather the accelerated adoption of all four levers is necessary to minimize the CRM supply risk to its absolute minimum. Hence, the study underscores the signifcance of increased research, innovation, and regulatory initiatives, along with raising social awareness, in efectively addressing the challenges faced by the CRM supply chain and contributing to a sustainable energy transition. (10.1007/s13563-024-00425-2)
    DOI : 10.1007/s13563-024-00425-2
  • Comparison of the phase-field approach and cohesive element modeling to analyze the double cleavage drilled compression fracture test of an elastoplastic material
    • Coq Arnaud
    • Diani Julie
    • Brach Stella
    International Journal of Fracture, Springer Verlag, 2024. Brittle material Mode I fracture may be characterized by the double cleavage drilled compres- sion test. For linear elastic materials, the critical energy release rate, or fracture toughness, can be estimated simply using the linear elastic fracture mechanics. For other types of constitutive behavior, the material parameter has to be determined with numerical fracture modeling. In this paper, we have used two approaches, the phase-field damage model and the cohesive ele- ments, in order to estimate the critical energy release rate of an elastoplastic material. Firstly, we assessed the numerical models and discussed their parameters by comparison of available data from double cleav- age drilled compression experimental tests run on a sil- ica glass. Both phase-field damage and cohesive zone models were able to reproduce fracture initiation at the observed macroscopic stress for the linear elastic mate- rial. However, the material toughness could not be pre- dicted by the phase-field approach due to the result dependence on the model regularization parameter. Secondly, an elastoplastic methyl methacrylate poly- mer was submitted to the compression test in our lab. Both models were then extended for elastic-perfectly plastic materials. Crack initiation was obtained at the observed macroscopic strain for similar critical energy release rate ranges for both approaches, providing good confidence in the estimated material toughness. (10.1007/s10704-023-00755-2)
    DOI : 10.1007/s10704-023-00755-2
  • M-Voronoi and other random open and closed-cell elasto-plastic cellular materials: Geometry generation and numerical study at small and large strains
    • Hooshmand-Ahoor Z
    • Luo H
    • Danas K
    International Journal of Solids and Structures, Elsevier, 2024, 290. The present study deals with a numerical design strategy of a novel class of three-dimensional random Voronoitype geometries, called M-Voronoi. These materials comprise random, non-quadratic convex void shapes and non-uniform intervoid ligament thicknesses, and can span high-to-low relative densities. The starting point for their generation is a random adsorption algorithm (RSA) construction with spherical voids embedded in an incompressible, nonlinear elastic matrix phase. The initial RSA geometry is subjected to large elastic volume changes by prescribing Dirichlet boundary conditions. Due to the incompressibility of the matrix phase, the externally imposed volume changes lead to significant void growth. The numerical growth process may be stopped at any desired porosity. The proposed M-Voronoi process is general and allows the formation of isotropic (or anisotropic) designs. As a byproduct of the developed approach, we also present a novel remeshing technique allowing to read arbitrary geometries of one or multiple phases. The elasto-plastic properties of the M-Voronoi porous materials are numerically investigated at small strains as well as large compressive and shear loads. Their response is assessed by comparison with other well-known random and periodic porous geometries such as polydisperse porous materials with spherical voids (RSA), classical TPMS Gyroid geometries and random Spinodoid topologies. The results show that M-Voronoi and RSA (with spherical voids) geometries exhibit the stiffest elastic and highest flow stress response compared to the other two geometries. This study shows unambiguously that randomness may or may not lead to enhanced mechanical response such as higher stiffness or flow stress. (10.1016/j.ijsolstr.2024.112680)
    DOI : 10.1016/j.ijsolstr.2024.112680
  • QuadWire: an extended one dimensional model for efficient mechanical simulations of bead-based additive manufacturing processes
    • Preumont Laurane
    • Viano Rafaël
    • Weisz-Patrault Daniel
    • Margerit Pierre
    • Allaire Grégoire
    , 2024. This paper presents the basis of a new mechanical model named QuadWire dedicated to efficient simulations of bead-based additive manufacturing processes in which elongated beads are assembled to form 3D parts. The key contribution is to use a multi-particular approach containing 4 particles per material point to develop an extended 1D model capable of capturing complex 3D mechanical states, while significantly reducing computation time with respect to conventional approaches. Indeed, 3D models usually require at least 3 to 4 elements across the bead section, which results in fine discretization along the tangential direction to avoid conditioning issues, and therefore very fine mesh of the entire 3D part. In the QuadWire model, the bead height and thickness are internal dimensions, enabling a significantly coarser mesh along the tangential direction. Thus, despite the QuadWire has 12 degrees of freedom per material point instead of 3 for classical models, the total number of degrees of freedom is reduced by several order of magnitudes for large parts. The proposed model is classically developed within the framework of the principle of virtual power and standard generalized elastic media. Furthermore, the proposed approach includes native and manageable kinematic constraints between successive beads so that the stress state properly evolves during fabrication. Finite element analysis is used for numerical implementation, and the QuadWire stiffness parameters are optimized so that the mechanical response fit conventional 3D approaches. To validate and demonstrate the capabilities of the proposed strategy, the evolution of displacements and stresses in fused deposition modeling of polylactide is simulated.
  • Very fast simulation of growth competition between columnar dendritic grains during melt pool solidification
    • Dollé Quentin
    • Weisz-Patrault Daniel
    , 2024. This paper presents a very fast numerical approach to simulate microstructures resulting from melt pool solidification including growth competition of columnar dendritic grains, and equiaxed grains nucleated from the melt. To reduce computation time, an upscaling strategy is proposed, which instead of considering each dendrite individually consists in defining an average solidification front based on physically-informed dendritic growth velocity. The proposed approach also relies on dendritic preferred growth direction, and favorably oriented grain criterion to determine which grain survives the competition. One of the key contribution to significantly reduce the total number of degrees of freedom is to use Voronoi tessellations instead of regular grids for numerical implementation. Results have been compared to experimental data, and to phase field and cellular automaton simulations. Simulated microstructures are similar as those obtained with cellular automaton, while computation cost is dramatically reduced. In addition, a convergence analysis is provided for three-dimensional simulations, with thermal conditions corresponding to metal additive manufacturing to demonstrate how the present work can be used in practice.
  • Very fast simulation of growth competition between columnar dendritic grains during melt pool solidification
    • Dollé Quentin
    • Weisz-Patrault Daniel
    Computational Materials Science, Elsevier, 2024, 243, pp.113112. This paper presents a very fast numerical approach to simulate microstructures resulting from melt pool solidification including growth competition of columnar dendritic grains, and equiaxed grains nucleated from the melt. To reduce computation time, the key contribution is the development of an upscaling strategy, which instead of considering each dendrite individually consists in defining an average solidification front based on physically-informed dendritic growth velocity. The proposed approach also relies on dendritic preferred growth direction, and favorably oriented grain criterion to determine which grain survives the competition. To significantly reduce the total number of degrees of freedom Voronoi tessellations are used instead of regular grids for numerical implementation. Indeed, 3D regular grids typically leads to ${N}^3$ degrees of freedom while Voronoi tessellations lead to only 3${N}$, which dramatically reduces computation cost. This work is therefore a high-throughput approach enabling large data set generation to explore statistical features of microstructures with respect to melt pool properties. Results have been compared to experimental data, and to phase field and cellular automaton simulations in 2D only. Simulated microstructures are similar as those obtained with cellular automaton. Comparisons in 3D are left for future work. In addition, a convergence analysis is provided for 3D simulations, with thermal conditions corresponding to metal additive manufacturing to demonstrate how the present work can be used in practice. (10.1016/j.commatsci.2024.113112)
    DOI : 10.1016/j.commatsci.2024.113112
  • The T-coercivity approach for mixed problems
    • Barré Mathieu
    • Ciarlet Patrick
    Comptes Rendus. Mathématique, Académie des sciences (Paris), 2024, 362, pp.1051-1088. Classically, the well-posedness of variational formulations of mixed linear problems is achieved through the inf-sup condition on the constraint. In this note, we propose an alternative framework to study such problems by using the T-coercivity approach to derive a global inf-sup condition. Generally speaking, this is a constructive approach that, in addition, drives the design of suitable approximations. As a matter of fact, the derivation of the uniform discrete inf-sup condition for the approximate problems follows easily from the study of the original problem. To support our view, we solve a series of classical mixed problems with the T-coercivity approach. Among others, the celebrated Fortin Lemma appears naturally in the numerical analysis of the approximate problems. (10.5802/crmath.590)
    DOI : 10.5802/crmath.590
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