Publications

2026

• High strain-rate failure mechanisms of additively manufactured IN718 Gyroid structures: Experiments and numerical insights
  
  • Weller Alexis
  • Querois Julie
  • Vallino Nicolas
  • Francart Charles
  • Forquin Pascal
  • Constantinescu Andrei
  International Journal of Impact Engineering, Elsevier, 2026, 218, pp.105826. (10.1016/j.ijimpeng.2026.105826)
  DOI : 10.1016/j.ijimpeng.2026.105826
• A VARIATIONAL FRAMEWORK FOR INCOMPATIBILITY-DRIVEN DEFORMATIONS
  
  • Amstutz Samuel
  • Le Thien-Nga
  • van Goethem Nicolas
  , 2026. We propose an incremental, variational model for elasto-plastic deformations in which a newly constructed incompatible strain tensor, linked to dislocation density through Kr¨oner’s relation, serves as the primary kinematical descriptor. The model also introduces a scalar internal variable, the compatibility modulus, governing both dissipation and the tangent elastic response, thereby providing a rate-independent framework capable of describing strain hardening. Numerical simulations exhibit localized deformation patterns and residual stresses consistent with dislocation-mediated plasticity. The higher-order structure arises intrinsically from strain incompatibility, providing a geometrically natural and unified framework for size-dependent effects.
• Equilibrium gigahertz acoustics reveals long-range confinement in liquids
  
  • Chaban Ievgeniia
  • Pezeril Thomas
  , 2026. Understanding how the mechanical properties of liquids confined within nanometer-scale gaps differ from bulk behavior is central to biophysics, lubrication, catalysis, electrochemistry, and surface science. Yet the characterization of ultrathin confined liquids remains challenging, as many existing approaches rely on destructive or intrusive contact-based techniques, mostly measuring the liquid flow in the low frequency regime. Here, we present a non-invasive, all-optical technique based on ultrafast laser ultrasonics that probes confined liquids at equilibrium in the gigahertz frequency range. The method measures the phase and amplitude of time-domain Brillouin scattering signals transmitted through liquid layers whose thickness is varied step by step with subnanometer effective sampling. Supported by numerical modeling of acoustic propagation and optical detection, these signals allow us to extract the thickness-dependent acoustic velocity and attenuation of confined liquids. We show that nanometric confinement modifies the GHz acoustic response of glycerol, the liquid crystal 8CB, and a butyl-based ionic liquid over unexpectedly long spatial scales. These effects extend from a few nanometers to several tens of nanometers and reveal bound interfacial layers, acoustic stiffening, and enhanced solid-like behavior under confinement. Our results open a route to probing liquid confinement in a scarcely explored regime: dynamically measured at gigahertz frequencies, yet sufficiently weakly perturbative to preserve the equilibrium confined state.
• Homogenization of an elastic laminate with a boundary. Part II: Illustration and validation at second order
  
  • Thbaut Manon
  • Audoly Basile
  • Bleyer Jeremy
  • Lestringant Claire
  , 2026. Based on the method proposed in the companion paper, we derive an effective model for a two-phase laminate having spatial period~$\eta$. The laminate occupies an infinite strip-like domain in the plane, having width~$L$ along the transverse direction~$x_1$. It has piecewise-constant, periodic elastic properties in the longitudinal direction~$x_2$. We consider a periodic loading, so that the macroscopic displacement~$\mathbf{U}_{\eta} (x_1)$ is one-dimensional in the limit of well-separated scales ($\eta \rightarrow 0$, fixed $L$). We derive the effective one-dimensional energy functional $\Phi_{\eta} [\mathbf{U}]$ to order~$\eta^2$. It depends on the strain gradients, and includes boundary terms that capture the boundary layers in an effective way. By making $\Phi_{\eta} [\mathbf{U}]$ stationary order by order, we obtain the equilibrium boundary-value problem for $\mathbf{U}_{\eta} (x_1)$. The order-$\eta^2$ accuracy of the effective model is verified numerically by comparing its predictions to finite-element solutions of the microscopic problem. The comparison is based on the apparent stiffness in a variety of loading scenarios, {\emph{i.e.}}, compression in the direction transverse to the fibers, traction applied on one of the phases at the boundary, and body forces that are either parallel or transverse to the microstructure. The effective model predicts in a unified and asymptotically correct way the size effect associated with the different loading scenarios.
• Homogenization of an elastic laminate with a boundary. Part I: effective model at all orders
  
  • Thbaut Manon
  • Audoly Basile
  • Lestringant Claire
  , 2026. By combining higher-order homogenization and boundary-layer analysis, we derive an effective model for a periodic elastic laminate occupying a half-plane in 2D. The analysis is based on formal two-scale expansions and is asymptotically correct in the limit $\eta \rightarrow 0$ where the spatial period of the microstructure is much smaller than the macroscopic scale of the loading. The homogenization and boundary-layer problems are worked out at all orders in~$\eta$ and their solution is inserted into the microscopic energy of the laminate. Hierarchical integration formulas are then used to eliminate the fast variable, delivering the effective energy functional~$\Phi^{\star}_{\eta} [\mathbf{V}]$ in the form of an infinite series in powers of~$\eta$, depending on the macroscopic displacement~$\mathbf{V} (\mathbf{X})$. The effective model is thus identified at the energy level. By making the effective energy~$\Phi^{\star}_{\eta} [\mathbf{V}]$ stationary order by order in~$\eta$, we obtain the boundary-value problem for the macroscopic displacement~$\mathbf{V} (\mathbf{X})$. The boundary layers produced by the microscopic model are rendered in an effective way by the boundary terms. We identify compatibility conditions satisfied by these boundary terms, and show that they generate redundant effective boundary conditions at successive orders. Although this behavior is non-generic in the calculus of variations, we argue that it is desirable in the context of higher-order effective models.
• GreenMelt: Part-Scale Ultra-Fast Melt Pool Prediction in Laser Powder Bed Fusion Accounting for Latent Heat and Marangoni Convection
  
  • Weisz-Patrault Daniel
  , 2026. Predicting microstructure in Laser Powder Bed Fusion (LPBF) or laser surface scanning requires accurate thermal analysis—including melt pool shape resolution at the part scale—yet remains computationally prohibitive due to the coupling between macro-scale heat accumulation and meso-scale melt pool phenomena. Thermal history governs solidification microstructure, making its rapid and accurate prediction a prerequisite for process parameter optimization. In this work, we propose a two-scale thermal model, named GreenMelt, that couples a macroscopic module, capturing part-scale heat accumulation, with an ultra-fast mesoscopic module resolving the melt pool under conduction mode assumption and especially the zone where solidification takes place. The approach is formulated using Green's functions supplemented by physically-based distributed heat sources that account for the principal nonlinearities of the problem: latent heat of solidification, and temperature redistribution induced by outward or inward Marangoni convection, which is the main novelty of this contribution. The framework supports arbitrary laser scan paths and nonlinear thermal contributions without compromising computational efficiency and without requiring calibration of internal parameters. Experimental validation was conducted on five single laser traces on a bare IN625 plate, demonstrating agreement within 2.5\% on average on cross-section profiles. Comprehensive code-to-code verification was performed for single-track numerical experiments under various process parameters and across four different materials (IN718, IN625, 316L, and Ti6Al4V). The temperature field in the melt pool is computed in less than 20 seconds in average on a laptop, compared to more than 5~hours in average for equivalent computational fluid dynamics (CFD) simulations. Good quantitative agreement is maintained, with an average relative error in the mushy zone lower than 2\% in average. The model's capabilities are further demonstrated on a full three-dimensional LPBF numerical experiment, confirming its applicability at the part scale. This approach makes the rapid numerical optimization of process parameters — including laser power, velocity, and scan strategy — tractable, enabling fine control over microstructure and mechanical properties in industrial LPBF components.
• Efficient spectral Galerkin framework for nonlinear transient heat transfer in finite domains
  
  • Andrieux Théo
  • Ntinos Andreas
  • Upadhyay Manas V
  , 2026. Accurately modelling the temporal evolution of heterogeneous temperature fields requires resolving strong nonlinearities in the heat equation arising from temperature-dependent thermophysical properties, latent heats of transformation and any local heat sources/sinks. In this work, we present a spectral Galerkin (SG) framework to solve the fully nonlinear transient heat equation in finite domains to attain the accuracy of high-fidelity finite element (FE) simulations at considerably lower computational cost. The heat equation is reformulated into a linear reference problem with constant thermophysical properties and residual forcing terms. Solving the reference problem provides a complete three-dimensional orthonormal trigonometric basis, whose Galerkin projection reduces the heat equation to a set of modal ordinary differential equations (ODEs) in time; the reference operator is diagonal in the modal basis, and results in independent modal updates for a fixed nonlinear forcing. These ODEs can be integrated using exponential time differencing and iteratively corrected for nonlinearities. The SG method eliminates the global solve required by FE methods, and its use of structured grids allows efficient GPU parallelization. Applied to rapid laser-metal interactions, the SG solver reproduces high-fidelity FE temperature fields with less than 1% relative error while achieving 227-fold faster GPU runtimes. Applied to a partscale laser scanning study [Ramani et al., Additive Manufacturing 52 (2022) 102643], the method shows that accounting for evaporation and latent heat more than halves their proposed processing metric. The source code of the SG heat solver and some worked examples are available at https://github.com/manasvupadhyay/spectral_galerkin_heat under the Apache 2.0 license.
• 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
• 4D Printing of Magneto‐Active Soft Elastomers via Efficient Active Mixing Direct Ink Writing
  
  • Selvam Vignesh
  • Danas Kostas
  • Bodelot Laurence
  Advanced Materials Technologies, Wiley, 2026. ABSTRACT 4D printing relies on the 3D printing of materials that respond to various stimuli after printing. Among these, magneto‐active elastomers readily react to magnetic fields, particularly at high magnetic particle loadings. For soft silicones with high particle contents, direct ink writing (DIW) is the most appropriate printing technique. However, a major challenge remains, especially for very‐short‐pot‐life silicones: crosslinking starts once the base is mixed with the curing agent. Hence, a helical mixer with large blades operating at low speed within a large chamber is introduced for the first time in active mixing DIW to specifically address high‐particle‐content, short‐pot‐life silicones. This method offers a steady and efficient mixing of the two silicone components, both loaded with magnetic particles and a rheology modifier, just before extrusion, leading to consistent filament extrusion with even particle distribution in addition to extended printing times without further additives or elaborate control systems. A framework is presented for selecting print parameters, where only the extruder speed needs to be adjusted when switching between inks having different particle contents. The impact of printing strategy on mechanical properties is assessed, and magneto‐active structures that can find applications in tunable actuators, soft robotics, deployable structures, and surface morphing are demonstrated. (10.1002/admt.71264)
  DOI : 10.1002/admt.71264
• A probabilistic framework for irreversible kinetics
  
  • Upadhyay Manas V
  , 2026. A probabilistic framework for irreversible kinetics is proposed in which a constrained path functional $\mathcal J$ encodes constitutive physics and observations on the admissible history space $\mathcal H_{\rm ad}$, while a discrete Gibbs-type measure proportional to $\exp(-\mathcal{J}/\Theta)$ assigns probabilities to a candidate set $\mathcal{H} \subseteq \mathcal{H}_{\rm ad}$. The framework unifies forward-in-time evolution and inverse inference, which differ only through observations and how they constrain admissible histories. The parameter $\Theta$ controls epistemic uncertainty, and the measure is interpreted as a Bayesian posterior over histories. Maximizing this posterior is equivalent to simultaneous minimization of $\mathcal{J}$ over $\mathcal{H}$, distinguishing the continuous minimizer $h_{\rm cont}$ over $\mathcal{H}_{\rm ad}$ from the discrete maximum a posteriori (MAP) history $h_{\rm MAP}$ over $\mathcal{H}$. As $\Theta\to0$, the posterior concentrates on the discrete MAP set. For generalized standard material(GSM)-type incremental energy--dissipation functionals, seven forward-in-time examples show that, despite using the same incremental functionals, causal GSM evolution is generally only incrementally optimal. When minimizers are unique, observations are absent, and $h_{\rm cont}\in\mathcal{H}$, the strict ordering $\mathcal{J}(h_{\rm cont}) = \mathcal{J}(h_{\rm MAP}) < \mathcal{J}(h_{\rm GSM})$ holds, showing that the GSM history does not minimize the cost of the entire history. Finally, an endpoint-conditioned inverse problem with nonconvex energy demonstrates the finite-$\Theta$ capability of the framework to infer unobserved states and quantify uncertainty over admissible histories.
• Comparative Evaluation of Camera Modules for Real-time Deep Learning-Based Detection of Tomato Plants and Weeds on a Raspberry Pi Platform
  
  • Sharma Apoorva
  • Kumar Arun
  • Sharma Hemant Kumar
  Archives of Current Research International, Sciencedomain International, 2026, 26 (8), pp.332-342. Aims: To evaluate and compare three camera modules, namely a USB webcam, a smartphone camera, and a Raspberry Pi Camera Module, for real-time detection of tomato plants and weeds, in order to identify the most suitable imaging sensor for deployment in a precision spraying system. Study Design: Comparative experimental evaluation of camera hardware under static and simulated dynamic field conditions. Place and Duration of Study: Department of Farm Machinery and Power Engineering, G. B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India, between July and September 2024. Methodology: A You Only Look Once (YOLO)11n object detection model, trained to identify tomato plants and weeds, was deployed on a Raspberry Pi 4B for real-time inference. Three imaging sensors, a 2-megapixel (MP) USB webcam, a 64 MP smartphone camera (POCO M4 Pro) interfaced via the DroidCam application over Wi-Fi, and a 5 MP Raspberry Pi Camera Module interfaced through the Camera Serial Interface (CSI), were evaluated under static conditions and under conveyor-simulated dynamic conditions at 1 km/h. The modules were compared on resolution, interface type, integration complexity, image quality, detection accuracy, processing latency, and power requirement. Results: The USB webcam exhibited poor image quality and a processing latency of 1250–1365 milliseconds (ms). The smartphone camera achieved the highest image quality and detection accuracy but showed a latency of approximately 2,000–3,000 ms due to Wi-Fi-based streaming. The Raspberry Pi Camera Module recorded the lowest latency (700–900 ms), moderate-to-high detection accuracy, and required no external power source, giving it the most favourable overall balance among the three sensors. Conclusion: Data transmission pathway, rather than sensor resolution alone, was the decisive factor determining real-time deployability. The Raspberry Pi Camera Module was accordingly selected for the final precision spraying prototype, and these findings offer practical guidance for imaging sensor selection in edge-deployed, real-time precision agriculture systems. (10.9734/acri/2026/v26i82061)
  DOI : 10.9734/acri/2026/v26i82061
• Mechanics of surface accretion with application to inelastic bodies
  
  • Nevenchannyy Yury
  • Jabbour Michel
  • Guin Laurent
  , 2026, pp.106788. We derive a continuum theory of surface accretion that allows for inelastic behavior, thus going beyond existing 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 inelastic and elastic strains arising at attachment and their subsequent evolution. In doing so, 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, and isotropic viscoplasticity. By solving examples with spherical symmetry, we first demonstrate that our framework recovers existing analytical solutions for elastic bodies, while making explicit the assumptions underlying them. Second, for viscoplastic bodies, we show that, unlike in the elastic case where the solution is rate-independent, the mass flux acts as a mechanical loading parameter that determines the interplay between material addition and stress relaxation. This is of particular relevance to growth of rate-dependent materials such as lithium-metal electrodes in solid-state batteries. (10.1016/j.jmps.2026.106788)
  DOI : 10.1016/j.jmps.2026.106788
• 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
• On the limits of the energetic coupling between field dislocation mechanics and phase field crystal
  
  • Graini Aymane
  • Viñals Jorge
  • Upadhyay Manas V
  , 2026. This paper investigates the energetic coupling between Field Dislocation Mechanics (FDM) and the Phase Field Crystal (PFC) model proposed in Phys. Rev. B 102, 064109, 2020. While FDM correctly solves the initial boundary value problem of a continuum body with dislocation fields, PFC captures the underlying crystallographic structure. The coupling, which penalizes the L 2 distance between elastic distortion from FDM and configurational distortion from PFC in the L 2 sense, had been proposed to reconcile dislocation mechanics with crystallography in a single continuum framework. Variational analysis reveals that the coupling term acts as a divergence-driven forcing in the phase-field evolution that matches only the compatible (curl-free) parts of the distortion fields. Consequently, its contributions are insensitive to the incompatible (divergence-free) elastic distortion carrying all the information on dislocation topology. Furthermore, the nature of the configurational distortion causes mechanical boundary conditions to be transmitted diffusively from FDM to PFC rather than elastically. Numerical simulations demonstrate that this coupling cannot prevent the unnatural core spreading in FDM. Finally, it is shown that even in the most general case, an energetic coupling suffers from the same drawbacks, which limits its ability to integrate dislocation mechanics with crystallography.
• 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
• NN-PGD for surrogate modeling of PDEs on parametrized domains
  
  • Škardová Kateřina
  • Daby-Seesaram Alexandre
  • Genet Martin
  , 2026. This work presents an extension of the Neural Network-Proper Generalised Decomposition (NN-PGD) framework for constructing surrogate models of PDEs defined on parametrized domains. Using a mapping onto a reference domain, the method allows a single model to provide solutions across a range of geometries. The framework combines the PGD with physics-informed training, enabling the modes to be learned directly from the governing equations. The approach is demonstrated on a 2D linear elasticity problem on a parametrized hexagonal domain.
• Data-driven reduced modeling of pleural pressure
  
  • Álvarez-Barrientos Felipe
  • Herszkowicz Quentin
  • Duwat Adrien
  • Fetita Catalin
  • Maître Xavier
  • Rodriguez Dima
  • Genet Martin
  , 2026. Pulmonary digital twins could enhance clinical diagnosis and treatment, but still rely on simplified boundary conditions for mechanical simulations. To address this, we build a pleural pressure model based on dynamic MRI using a poromechanical approach. Higher-order SVD is applied to pressure estimates from 10 volunteers to extract distinct spatial and temporal modes and quantify their separability. This reduced-order model identifies common patterns across subjects, potentially related to physiological variables, supporting the development of more realistic boundary conditions.
• 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.
• 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