Publications

2026

• Longitudinal waves in two-dimensional quasi-periodic lattices
  
  • Comi Claudia
  • Moscatelli Marco
  • Marigo Jean-Jacques
  European Journal of Mechanics - A/Solids, Elsevier, 2026, 119, pp.106194. We study longitudinal wave propagation in a two-dimensional elastic lattice formed by parallel bars coupled by slender beams whose out-of-plane thickness is modulated according to an Aubry-André-Harper profile. This modulation can yield periodic or quasi-periodic architectures depending on the choice of the parameters. Starting from the continuous bar-beam model, we derive a discrete formulation and analyze the existence of bounded solutions and band-gaps as functions of the modulation amplitude and geometry. We provide analytical criteria for band-gap nucleation and explicit estimates of gap widths, and we show how quasiperiodicity can both create new gaps and shrink existing ones relative to the periodic case. The results offer new insights on the influence of quasi-periodicity in 2D elastic lattices. We show numerically how this class of structures can be exploited to achieve topological pumping of elastic waves. (10.1016/j.euromechsol.2026.106194)
  DOI : 10.1016/j.euromechsol.2026.106194
• Mechanical Cloaking of Halftoned Imagery
  
  • Martínez Jonàs
  • Brisard Sébastien
  • Danas Kostas
  • Garner Eric
  • Kumar Siddhant
  • Lefebvre Sylvain
  ACM Transactions on Graphics, Association for Computing Machinery, 2026, 45 (4). Cloaking objects with metamaterials has been extensively studied to hide internal objects across various physical properties, including optical, acoustic, and thermal. We explore a new direction in mechanical cloaking: halftoning an image using a porous structure that behaves like a uniform, linear, isotropic material and visually matches a target image. For an external observer, this creates the surprising effect where the object appears mechanically isotropic and homogeneous while its porous structure resembles a target image. We introduce a parametric class of porous structures suitable for this problem, as demonstrated by numerical experiments. The structures we define offer a wide range of visual contrasts, enabling effective halftoning while maintaining near isotropic effective mechanical properties. (10.1145/3811394)
  DOI : 10.1145/3811394
• Unraveling plastic strain localization in aluminum polycrystals by coupling of in situ high-resolution digital image correlation and crystal plasticity
  
  • Girault Florian
  • Toualbi Louise
  • Tanguy Alexandre
  • Ask Anna
  • Charkaluk Eric
  Mechanics of Materials, Elsevier, 2026, 217, pp.105645. This study investigates the localization of plastic deformation in a small-grain 7xxx-series aluminum polycrystal. A particular focus is placed on analyzing the contribution of certain key features of the microstructure in the onset of local plasticity. One of the strengths of this study is the use of diverse experimental and numerical approaches. Particular attention was given to the methodological aspects of these approaches, which are used both for statistical and local analyses. A nanometric speckle pattern was used to track the intra-granular deformations of tensile specimens using high-resolution digital image correlation (HRDIC). These deformations were then correlated with relevant microstructure data. In parallel, a crystal plasticity model was implemented. Its purpose was to complete the experimental results and provide additional data inaccessible with DIC. A very weak correlation between plastic activity and crystallographic grain-averaged data was demonstrated, even for the Schmid factor. This shows the significance of the polycrystal effect due to the interactions between neighbor grains. Intermetallics exhibit a hard and brittle behavior, which triggers strain localization in their vicinity. However, particle clusters do not manifest any specific behavior. In addition, the experimental maps showed deformation concentrations near grain boundaries, of which the most deformed ones were detected using a machine learning procedure. The associated deformation mechanisms were numerically investigated, and it was shown that most grain boundaries can lead to stress and/or strain localization, even those featuring a good slip compatibility. (10.1016/j.mechmat.2026.105645)
  DOI : 10.1016/j.mechmat.2026.105645
• Modélisation à double porosité d'une microstructure à trois phases pour la perfusion pulmonaire
  
  • Xiao Haotian
  • Genet Martin
  , 2026. Modélisation à double porosité d'une microstructure à trois phases pour la perfusion pulmonaire
• Modélisation biomécanique des muscles extra-oculaires appliqué à un modèle optique
  
  • Bonnafé Julien
  • Allain Jean-Marc
  • Rio David
  , 2026. Nous développons un modèle éléments finis de l’œil, incluant le globe oculaire, les muscles extra-oculaires, le nerf optique et la graisse orbitale, afin d’analyser les efforts mécaniques lors de mouvements oculaires. Nous utilisons un modèle de Hill pour les muscles. Notre modèle inclut des contraintes internes (pression intraoculaire...). Au travers d’une géométrie simplifiée, nous montrons l’importance des contraintes internes et de la prise en compte de la graisse pour reproduire des mouvements réalistes de l’œil, et leurs conséquences sur la réfraction.
• A class of optimal virtual fields for inverse problems in elasticity
  
  • Chibli Nagham
  • Genet Martin
  • Imperiale Sébastien
  Comptes Rendus. Mécanique, Académie des sciences (Paris), 2026, 354 (G1), pp.417-449. This work addresses the identification of nonhomogeneous constitutive parameters from full-field measurements in both linear and nonlinear elasticity, considering incompressible as well as compressible materials. The inverse identification procedure relies on the Virtual Fields Method (VFM), which is based on the principle of virtual work with specifically chosen virtual fields. We propose an optimal class of virtual fields, designed to optimize the reconstruction stability with respect to measurement noise. A series of numerical experiments illustrate the effectiveness of the proposed approach. The method exhibits moderate sensitivity to measurement noise and remains robust even when the boundary conditions are only partially known. (10.5802/crmeca.361)
  DOI : 10.5802/crmeca.361
• Homogenizing elastic lattices with mechanisms
  
  • Audoly Basile
  • Lestringant Claire
  • Nassar Hussein
  European Journal of Mechanics - A/Solids, Elsevier, 2026, 117, pp.105956. We propose an asymptotic method for homogenizing periodic elastic lattices that works in the presence of mechanisms, both of the macroscopic type (strain-producing modes) and of the microscopic type (internal modes). When a microscopic mechanism is present, the unit-cell problem produced by classical homogenization is singular. It can be fixed by including the amplitude~$\theta (\mathbf{X})$ of the mechanism as an additional macroscopic degree of freedom (enrichment variable) contributing to the effective energy via its gradient $\nabla \theta (\mathbf{X})$. When a macroscopic mechanism is present, homogenization delivers a degenerate effective energy at leading order, which can be regularized by accounting for the strain gradient. We introduce an asymptotic second-order homogenization scheme that integrates these two features: it delivers an effective energy capturing both the strain-gradient effect $\nabla \mathbf{\varepsilon} (\mathbf{X})$ relevant to macroscopic mechanisms, and the $\nabla \theta (\mathbf{X})$ regularization relevant to microscopic mechanisms, if any is present. The versatility of the approach is illustrated with a selection of lattices displaying a variety of effective behaviors. It follows a unified pattern that leads to a classification of these effective behaviors. Whereas the procedure delivers known effective models for elastic lattices without mechanisms, it can generate novel effective models for lattices possessing mechanisms. (10.1016/j.euromechsol.2025.105956)
  DOI : 10.1016/j.euromechsol.2025.105956
• Experimental Investigation of Rock Salt Rheology Under Multiple Load Paths Applied in the Laboratory and in Salt Mines
  
  • Blanco-Martín Laura
  • Jiménez Camargo Jubier Alonso
  • Gharbi Hakim
  • Dimanov Alexandre
  • Bornert Michel
  • Brouard Benoit
  Rock Mechanics and Rock Engineering, Springer Verlag, 2026. An extensive experimental program on rock salt comprising short-term and long-term tests has been performed on samples from the same origin and prepared and preconditioned using the same protocols. The main targets are to investigate the thermo-mechanical response of rock salt under different load paths and to produce a large database on which constitutive models can be formulated and calibrated. A total of 17 tests have been conducted, including four uniaxial experiments. Temperatures range between 8 and 60 °C, and some tests last more than 2 years. The experiments cover a differential stress range relevant for underground applications. Deviators within 0.2−4.5 MPa have been investigated through uniaxial creep experiments in salt mines to take advantage of very stable ambient conditions (particularly, temperature and relative humidity). Deviators up to 35 MPa have been investigated through confined experiments in the laboratory. Additionally, a cross-check quasi-uniaxial test (confinement of 0.2 MPa) has been performed in the laboratory under conditions similar to those of the mine, and proves that experiments in both settings can be combined to extend the range of investigated stresses. However, uniaxially loaded samples show higher strain rates than confined samples. X-Ray computed tomography suggests more micro-fracturing during the former. The results obtained under confined conditions are consistent and confirm the different stress dependency of the creep rate under low and high deviators. A modified Lemaitre model is used to analyze the results. Next steps include microstructural investigations to gain insight into the dominant deformation mechanisms under different thermo-mechanical loads, allowing for more predictive constitutive models. (10.1007/s00603-026-05496-x)
  DOI : 10.1007/s00603-026-05496-x
• On the accuracy of 2D microstructure simulations to predict formation of intergranular residual mechanical fields during rapid laser-metal interactions
  
  • Mohanan Nikhil
  • Chadwick Alexander F
  • Samaei Arash
  • Bleyer Jérémy
  • Helfer Thomas
  • Wagner Gregory J
  • Voorhees Peter W
  • Upadhyay Manas V
  , 2026. The extent to which a three-dimensional extrusion of a two-dimensional microstructure (2DM) can reproduce the thermomechanical response of a fully three-dimensional microstructure (3DM) is investigated. A multi-physics numerical framework coupling computational thermal fluid dynamics (CFD), phase-field (PF) solidification, and thermo-elasto-viscoplastic finite element (TEVP-FE) modeling is employed to simulate a single laser line scan on a 316L stainless steel substrate. The temperature evolution obtained from CFD and the final microstructure predicted by PF simulations are used to perform two TEVP-FE simulations that differ only in the representation of the microstructure: 2DM and 3DM. Residual stresses, plastic strains, and Nye's tensor are compared at both local and statistical levels. The 2DM approximation captures the overall spatial evolution trends and the order of magnitude of residual stresses, but it does not reproduce the localization of shear stresses, plastic strains, and Nye's tensor, which is strongly influenced by the 3D grain morphology. Nevertheless, comparison of grain surface-averaged quantities on the lasered surface shows that the intergranular mechanical fields predicted by 2DM and 3DM match well in magnitudes and evolution trends. These results quantify the advantages and limitations of 2D microstructure approximations and provide guidance on the model complexity required for predicting intergranular mechanical fields at local and statistical levels.
• Mechanics of surface accretion with application to inelastic bodies
  
  • Nevenchannyy Yury
  • Jabbour Michel
  • Guin Laurent
  , 2026. This paper presents a continuum theory of surface accretion that allows for inelastic behavior thus going beyond the models for elastic growth. We employ a Lagrangian framework with a time-dependent arbitrary reference configuration and adopt a multiplicative decomposition of the deformation gradient to account for both the inelastic and elastic strains arising at attachment and their subsequent evolution. Specifically, we formulate the governing equations and identify the additional boundary conditions required at the accreting boundary. The inelastic behavior is then specialized to isochoric, irrotational, isotropic viscoplasticity. Addressing examples with spherical symmetry, we first demonstrate that our framework recovers existing analytical solutions for elastic bodies, while making explicit their underlying assumptions. Second, for viscoplastic bodies, we show that, unlike the elastic case, where the solution is rate-independent, the mass flux acts as a mechanical loading parameter, determining the interplay between material addition and stress relaxation. This is of particular relevance for growth of rate-dependent materials such as lithium-metal electrodes in solid-state batteries.
• Stability of time stepping methods for discontinuous Galerkin discretizations of Friedrichs' systems
  
  • Imperiale Sébastien
  • Joly Patrick
  • Rodríguez Jerónimo
  , 2025. In this work we study new various energy-based theoretical results on the stability of s-stages, s-th order explicit Runge-Kutta integrators as well as a modified leap-frog scheme applied to discontinuous Galerkin discretizations of transient linear symmetric hyperbolic Friedrichs' systems. We restrict the present study to conservative systems and Cauchy problems.
• Continuous microstructure variations with graded properties in directed energy deposition
  
  • Bréhier Michèle
  • Weisz-Patrault Daniel
  • Tournier Christophe
  Additive Manufacturing Letters, Elsevier, 2026, 17, pp.100372. <div><p>Directed energy deposition additive manufacturing is a versatile technique for fabricating complex geometries, where precise control of process parameters is crucial for tailoring microstructure and part properties. Microstructure control strategies usually involve variation of material composition (i.e., functionally graded materials) or interlayer time delay. However, the obtained microstructures are usually uniform in the print direction and exhibit sharp transitions from one layer to the next in the build direction. This paper targets continuous microstructural variation by exploiting active cooling strategies to control cooling conditions. To do so, the scanning speed is continuously varied, necessitating accommodating the bead size variations with non-standard trajectory generation based on a phenomenological law. The proposed strategy is demonstrated on thin-wall structures made of IN718 using a powder-based laser directed energy deposition. The results reveal a continuous microstructural transition along the print direction, characterized by two distinct microstructural regimes with markedly different morphological features and crystallographic textures. This demonstrates the capability of scanning speed modulation to engineer heterogeneous microstructures within a single component, offering insights into tailoring material properties for specific engineering applications.</p></div> (10.1016/j.addlet.2026.100372)
  DOI : 10.1016/j.addlet.2026.100372
• Microscale Architected Materials for Elastic Waveguiding: Fabrication and Dynamic Characterization across Length and Time Scales
  
  • Kannan Vignesh
  • Dorn Charles
  • Drechsler Ute
  • Kochmann Dennis
  Physical Review X, American Physical Society, 2026, 16 (1), pp.011047. We present an experimental protocol for the fabrication and characterization of scalable microarchitected elastic waveguides. Using silicon microfabrication techniques, we develop free-standing 2D truss-based architected waveguides with a maximum diameter of 80 mm, unit cells size of 100 μ m , and minimum beam width of 5 μ m , thus achieving scale separation. To characterize elastic wave propagation, we introduce a custom-built scanning optical pump-probe experiment that enables contactless excitation of elastic wave modes and full spatiotemporal reconstruction of wave propagation across hundreds of unit cells with subunit cell resolution. Results on periodic architectures show excellent agreement with finite element simulations and equivalent experimental data at larger length scales. Motivated by scalable computational inverse design, we fabricate a specific example of a spatially graded waveguide and demonstrate its ability to guide elastic waves along an arbitrary predesigned path. (10.1103/21w4-zn1s)
  DOI : 10.1103/21w4-zn1s
• Locally implicit and stabilized explicit time schemes for transient visco-elastic wave propagation problems
  
  • Vasanthan Vinduja
  • Imperiale Alexandre
  • Imperiale Sébastien
  Journal of Numerical Mathematics, De Gruyter, 2026. In the context of numerical methods for time-domain wave propagation problems, combining high-order lumped finite elements with an explicit time scheme is a popular approach for either inviscid or visco-elastic models. This strategy has proven to be efficient in numerous cases. However, when dealing with non-uniform meshes or high-contrast materials, the stability condition on the time step becomes drastically stringent. One can encounter such configurations when meshing unfortunate CAD input le, e.g. when dealing with heterogeneous materials where neighboring heterogeneities produce very small elements in-between them, or when considering materials with high and localized wave velocities. To address efficiently these configurations, we propose to adapt the locally implicit and stabilized leapfrog methods to the Kelvin-Voigt, Maxwell and Zener visco-elastic models. We prove using energy arguments that the global stability condition of these schemes can be much more favorable compared to a fully-explicit scheme, decreasing the number of iterations for a fixed time window. We illustrate our approaches with 2D and 3D numerical test cases related to ultrasonic non-destructive testing experiments. (10.1515/jnma-2025-0044)
  DOI : 10.1515/jnma-2025-0044
• A projection scheme for an incompressible soft material poromechanics model
  
  • Barré Mathieu
  • Grandmont Céline
  • Moireau Philippe
  IMA Journal of Numerical Analysis, Oxford University Press (OUP), 2026. In this work, we propose and analyse a new scheme to discretize the linearized version of a rather general poromechanics model adapted to biological tissues perfusion. This model, which is related to – albeit different from – Biot equations, involves unsteady solid and fluid momentum balance equations that are further coupled through an incompressibility constraint, a pore pressure and permeability terms. The key feature of the scheme is to decouple the solid, fluid and pressure unknowns at each time step by means of a projection method, composed of a prediction and a correction step. We perform a complete stability analysis of the scheme depending on the implicit or explicit treatment of friction and pressure in the prediction step. Several boundary conditions are considered, including conditions coupling the solid and fluid phases on the boundary that are imposed at the discrete level using a Robin-Robin method. In the case of Dirichlet boundary conditions, we also provide a fully discrete error estimate as long as a discrete inf-sup condition is satisfied. The scheme properties and robustness with respect to physical parameters are illustrated by numerical experiments. Finally, its computational performance is compared with that of a monolithic approach.
• Stamps for Pattern Applications for DIC or Markers Tracking
  
  • Diani J.
  • Geraud G.
  • Coq A.
  • Kuzyara V.
  Experimental Techniques, Society for Experimental Mechanics, 2026. Digital image correlation requires a surface pattern to monitor deformation, and while spray paint is widely used for this purpose, it suffers from drawbacks such as limited reproducibility and poor control over speckle characteristics. This study aims to develop stamps to apply patterns with greater consistency and control, and to demonstrate that such pattern speckle performs comparably to traditional spray paint speckle. For that purpose, speckles were applied to polymer surfaces using two techniques, ink stamping of circular dots and conventional spray painting. Their quality was first evaluated through numerical assessments, followed by digital image correlation analyses under both small and large strains. Small-strain behavior was studied using synthetically deformed images based on sinusoidal displacements, while large-strain performance was assessed via uniaxial stretching of a holed elastomer sample. Both speckle application methods yielded similar results in terms of image correlation accuracy and robustness across deformation scales proving that the produced stamps offer a viable alternative to spray paint, providing significant advantages in terms of control, reproducibility, and customizability of the speckle pattern, without compromising performance. (10.1007/s40799-026-00875-z)
  DOI : 10.1007/s40799-026-00875-z
• Graded phononic metamaterials based on scalable microfabrication and design
  
  • Dorn Charles
  • Kannan Vignesh
  • Drechsler Ute
  • Kochmann Dennis
  Nature Communications, Nature Publishing Group, 2026, 17 (1), pp.3192. Abstract Metamaterials’ engineered internal structures enable customized material properties beyond those found in nature, such as the capability to guide, attenuate, and focus waves at will. Phononic metamaterials aim to manipulate mechanical waves, with broad applications in acoustics, elastodynamics and structural vibrations. A key bottleneck in the advancement of phononic metamaterials is their scalability beyond tens of unit cells per spatial dimension, which equally affects their design, simulation, and fabrication. Here, we present a framework for scalable inverse design of spatially graded phononic metamaterials for elastic wave guiding, together with a scalable microfabrication method. This framework enables the design and realization of complex waveguides including hundreds of thousands of unit cells, potentially extendable to millions with no change in protocol. Scalable designs are optimized with a ray tracing model for waves in spatially graded beam lattices and fabricated by photolithography and etching of silicon wafers, to create free-standing microarchitected films. Wave guiding is demonstrated experimentally by using pulsed laser excitation and interferometric displacement measurements. Broadband wave guiding is demonstrated, indicating the promise of our scalable design and fabrication methods for on-chip elastic wave manipulation. (10.1038/s41467-026-69888-x)
  DOI : 10.1038/s41467-026-69888-x
• Biointegration of a partially decellularized tracheal scaffold in a porcine model - preliminary results
  
  • Vigouroux Augustin
  • Bonnin Yannis
  • Gendron Nicolas
  • Kellouche Sabrina
  • Agniel Rémy
  • Bruneval Patrick
  • Balvay Daniel
  • Allain Jean-Marc
  • Chhun Stéphanie
  • Kempf Hervé
  • Hugon Romain
  • Devriese Magali
  • Sansac Caroline
  • Larghero Jérôme
  • Arakelian Lousineh
  • Thierry Briac
  Scientific Reports, Nature Publishing Group, 2026, 16 (1), pp.10121. Some pediatric tracheal pathologies remain therapeutic dead ends for which current palliative strategies are fraught with serious complications. With the aim of a tracheal replacement, our team has previously developed and patented a clinical grade partially decellularized trachea (PDT) from porcine tracheas. The aim of this work was to study and compare the biointegration mechanisms of this PDT in vivo, in a pig cervical muscle, with or without immunosuppressant. The secondary objective was to evaluate the optimal maturation time of the PDT in this heterotopic position. In total, 11 female Large White/Landrace pigs, weighing between 50 and 70 kg were included in this study. The mean age of the animals at the implantation was 4.8 months. The PDTs were implanted in a cervical muscle of pigs for either 28 days, with or without cyclosporin A treatment, or for 56 days without immunosuppression. Histological evaluation showed very good PDT biointegration, characterized by neovascularization and fibroblast colonization, and no detectabale infection. Additionally, tissue and blood analyses showed no signs of graft rejection or surrounding tissue necrosis. Immunosuppression did not show any superiority in terms of biointegration after 28 days of treatment. After 56 days of implantation, a more significant degradation of the cartilage. Therefore, the optimal condition for PDT maturation proved to be 28 days, without immunosuppression. (10.1038/s41598-026-37823-1)
  DOI : 10.1038/s41598-026-37823-1
• Rapid estimation of microstructure using infrared imaging and solidification modeling in wire-laser directed energy deposition
  
  • Dollé Quentin
  • Bréhier Michèle
  • Berté Emmanuel
  • Witz Jean-Francois
  • Tournier Christophe
  • El Bartali Ahmed
  • Weisz-Patrault Daniel
  , 2026. The widespread deployment of Directed Energy Deposition Additive Manufacturing is limited by the lack of control over the produced material depending on process parameters: in particular, the microstructure resulting from rapid solidification. While cost-efficient numerical simulations have been developed to predict temperature evolution and microstructure, their reliability hinges on high-quality experimental validation. This study first addresses this challenge by introducing a simple and cost-effective infrared measurement procedure that combines a single-band camera and a dual-band pyrometer to quantitatively measure temperature fields during wire-laser DED. To do so, the apparent emissivity field was identified and found to be highly heterogeneous due to localized cover gas and oxidation. In addition, to enable rapid microstructure estimation, fast computational procedures are proposed to (i) calculate the thermal gradient field using Fast Fourier Transform, and (ii) simulate solidification in the melt pool, including competitive growth between columnar dendritic grains, using a recent Voronoi tessellation-based model. The computation time is compatible with the development of an online monitoring procedure. The resulting microstructure predictions were validated against Electron Backscatter Diffraction measurements, demonstrating excellent qualitative agreement. This work validates the proposed approach as a promising tool for closed-loop control of microstructure during DED.
• One- and Two-Photon Polymerization of Solvent- and Filler-Free Aromatic Organic Precursors: Toward 3D-Printed Semiconducting Microstructures
  
  • Noè Camilla
  • Laroui Sami
  • Zucchi Gaël
  • Bodelot Laurence
  ACS Applied Engineering Materials, ACS, 2026, 4 (2), pp.926-935. Over the past decades, a great deal of attention has been dedicated toward developing semiconductive polymers (SP), which are now considered as a critical class of photoactive and electroactive materials. However, the processing of many SPs involves the use of solvents, leading to the fabrication of samples with limited shapes, mostly flat 2D thin films. To develop 3D-shaped materials with potential semiconducting properties, this work tackles the development of solvent-and filler-free resins for the fabrication via additive manufacturing of microscale organic semiconductors. Two molecular liquids based on electron-rich carbazole and triarylamine units are used to formulate photoresists. The successful reactivity of the formulations was investigated, both at the macroscopic scale (one-photon polymerization through UV curing) and at the microscopic scale (two-photon polymerization (2PP) via direct laser writing), with Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. Subsequently, the thermal properties of the macroscopic samples were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Optimization of the printing parameters for 2PP led to the elaboration of 3D micrometer-scale samples whose morphology was assessed by scanning electron microscopy (SEM). Finally, electrical measurements revealed a semiconducting behavior as the samples were found to conduct current after p-doping with iodine. (10.1021/acsaenm.5c01101)
  DOI : 10.1021/acsaenm.5c01101
• Mean stress effects and energy-based modeling of fatigue behavior in artificially cemented rock-like materials under cyclic loading
  
  • Darsanj Solmaz
  • Emami Tabrizi Mehrdad
  • Constantinescu Andrei
  Bulletin of Engineering Geology and the Environment, Springer Verlag, 2026, 85 (2), pp.113. (10.1007/s10064-025-04757-3)
  DOI : 10.1007/s10064-025-04757-3
• Additive Manufacturing repair of damaged parts of a reusable launcher
  
  • Girault Florian
  , 2026. The objective of the thesis is to answer the problem encountered by CNES in the repair of reusable launch vehicle parts. The particularity comes from the fact that the chemical nature of the alloys constituting the candidate parts does not allow theuse of the Additive Manufacturing processes conventionally used, which imply a passage in liquid phase ofthe material and induce, in addition to the problems of segregation and cracking which can be controlled, an evaporation of certain elements of alloy. This work studies, in the case of aerospace aluminium alloys, the effect on microstructures and mechanical behaviourof different alternative repair options. In particular,the use of so-called solid-phase friction-stir processessuch as AFSD (Additive Friction Stir Deposition) is investigated. The analyses performed are multi-scale,examining the quality of the deposited material, the interface with the damaged part, and the effects of the repair on the part.
• Finite element modelling for the reproduction of dynamic OCE measurements in the cornea
  
  • Merlini Giulia
  • Imperiale Sébastien
  • Allain Jean-Marc
  Journal of the Mechanics and Physics of Solids, Elsevier, 2026, 206, pp.106363. Recent advances in dynamic elastography, particularly through optical coherence tomography combined with transient excitations have enabled rapid, localized, and non-invasive mechanical data acquisition of the cornea. This dataopens the path to early-detection of pathologies and more accurate treatment. However, the analysis of the wave propagation is a complex mechanical problem: the cornea is a structure under pressure, with non-linear material behavior. Thus, computational analysis are needed to extract mechanical parameters from the data. In this study, we present a time-dependent finite element model for the reproduction of transient shear wave elastographic measurements in the cornea. The mechanical problem consists in a smallamplitude wave propagating in the cornea, largely deformed by intraocular pressure in physiological conditions. The model accounts for anisotropic, hyperelastic, and incompressible behavior of the cornea, as well as its accurate geometry, and the preloaded condition. We have implemented two different numerical approaches to solve first the static non-linear inflation of the cornea and then the linear wave propagation problem to reproduce the measurements. We investigate the impact of material anisotropy and prestress on wave propagation and demonstrate that intraocular pressure critically influences shear wave velocity. Additionally, by introducing a localized mechanical defect to simulate a pathological defect, we show that simulated shear wave can detect and quantify mechanical weaknesses, suggesting potential as a diagnostic tool to assess corneal health. (10.1016/j.jmps.2025.106363)
  DOI : 10.1016/j.jmps.2025.106363
• A stationarity principle generating effective boundary conditions for second-order homogenization
  
  • Thbaut Manon
  • Audoly Basile
  • Lestringant Claire
  Journal of Elasticity, Springer Verlag, 2026, 158 (1), pp.15. We derive an effective model for a periodic chain of linearly-elastic springs, achieving second-order accuracy in the scale separation parameter $\varepsilon \ll 1$. The chain has finite length and is made up of springs connecting both nearest- and next-nearest-neighbors: it serves as a one-dimensional prototype for higher-order periodic homogenization problems with boundaries. This type of problem has been approached by inserting two-scale expansions into the equations of equilibrium in the bulk and by matching them with boundary-layer solutions. We explore an alternative method operating at the energy level, bypassing the cumbersome matching procedure. We start from an ansatz of the microscopic displacement accounting for both boundary layers and for small-scale fluctuations in the bulk, and insert it into the discrete energy. This yields a continuous energy functional depending on the macroscopic displacement $u$, in the form of a series expansion in powers of $\varepsilon$. We call it a {\tmem{pseudo-energy}} $\Phi_{\varepsilon} [u]$ as it is not positive when truncated at order~$\varepsilon^2$. The boundary terms in the pseudo-energy account for boundary layers in an effective way. By making the pseudo-energy stationary order by order in $\varepsilon$, we derive the homogenized equations of equilibrium along with effective boundary conditions. We provide quantitative validation showing that the effective model is correct to second order. We point out the special form of the effective higher-order tractions, which has been overlooked in strain-gradient theories proposed so far. (10.1007/s10659-026-10190-8)
  DOI : 10.1007/s10659-026-10190-8
• SCAR : a self-consistent recurrent cell for real-time finite strain elastoplastic simulations
  
  • Lesueur Louis
  • Weisz-Patrault Daniel
  • Thorin Anders
  , 2026. Complex fabrication and forming processes operating under finite strains could benefit significantly from optimization loops of process parameters, which are often hindered by the prohibitive computational costs of process modeling. Neural networks present a promising solution to derive fast and accurate surrogate models, thereby enabling such optimizations. Furthermore, many processes involve substantial inherent variability, and hence often require manual process control. Neural networks could also provide real-time predictions that would greatly assist in decision-making. Although recursive neural networks have been applied in mechanics, their use in modeling elastoplastic behavior at finite strains remains underexplored. This paper introduces a new family of self-consistent recurrent cells, referred to as SCAR. These cells are specifically designed to address history-dependent problems, such as elastoplasticity, and ensure compliance with key properties required for such applications. To evaluate the SCAR cells, a generic architecture named PlastiNN, featuring a spatially resolved neural decoder, is employed. This approach results in faster training times and more accurate predictions in comparison to commonly used architectures. Additionally, PlastiNN can accommodate a series of successive loads on a workpiece, which is critical for most fabrication and forming processes. The effectiveness of this strategy is demonstrated by comparing SCAR cells to other recurrent cells within the PlastiNN architecture through a comprehensive benchmark including two datasets of 1D and 3D simulations, ranging from challenging toy applications to more realistic industrial test cases. Results highlight the superiority of the proposed recurrent neural network architecture for modeling elastic-plastic behavior at finite strains in engineering processes.