European Journal of Mechanics A-Solids最新文献

{"title":"Assessment of the viscoelastic and multi-axial mechanical response of POM using hypoelastic and hyperelastic constitutive models","authors":"Björn Stoltz ,&nbsp;Martin Kroon","doi":"10.1016/j.euromechsol.2025.105625","DOIUrl":"10.1016/j.euromechsol.2025.105625","url":null,"abstract":"<div><div>The mechanical behaviour of thermoplastics is strongly rate-dependent. One thermoplastic that is commonly used in industrial applications is polyoxymethylene (POM). In a previous paper (Mechanics of Time-dependent Materials, 2024, vol 28, p 43-63), the uniaxial tensile properties of POM were tested, and in the present study, those tests are complemented by compression tests, bending tests, and punch tests.</div><div>The test data in this study can be divided into calibration data and verification data. The calibration experiments consist of both tensile and compression tests carried out in monotonic loading, stress relaxation, and zero-stress creep. Three-point bending and quasi-static punch tests are used as verification tests. Overall, the experiments showed good repeatability, and there was a low dispersion in the experimental results.</div><div>The paper compares the performance of three constitutive models that have been developed for modelling these materials. Two hyperelastic models and one hypoelastic model are compared. The models are calibrated using the uniaxial data and then applied to the results from the more advanced tests. The material models are calibrated by utilizing commercially available optimization software.</div><div>All models have the ability to model visco-elasticity. Two of the models are network models with three visco-elastic branches/legs/phases. These two models are built in a similar way with two main novelties. The first novelty is that the stiffness can vary with the elastic deformation (in contrast to a standard neo-Hookean and Hookean model). The second novelty is that the exponent of viscous relaxation can vary with viscous deformation. The third model is an Eulerian model, meaning that all state variables are defined in the current state of the material.</div><div>Taken together, the models were able to describe the experimental results relatively well. It was concluded that they have different strengths and weaknesses. The hypoelastic model was able to describe the uniaxial calibration data best. On the other hand, this model became unstable at large deformations when simulating the punch tests. The two hyperelastic models could not model the zero-stress creep in the uniaxial tests but were able to predict the outcome from the punch tests quite well.</div><div>It was clear from the simulations that further model development is needed in order to capture all aspects of the experimental results.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"112 ","pages":"Article 105625"},"PeriodicalIF":4.4,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143563169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dragonfly-like wing structure enabled by a novel skeleton-reinforced neural style transfer assisted topology optimization and additive manufacturing","authors":"He Gang ,&nbsp;Zhou Yang ,&nbsp;Han Zhengtong ,&nbsp;Xu Ze ,&nbsp;Lv Hao","doi":"10.1016/j.euromechsol.2025.105631","DOIUrl":"10.1016/j.euromechsol.2025.105631","url":null,"abstract":"<div><div>Natural flyers, such as dragonflies, serve as excellent models for obtaining wing structures with superior performance due to their excellent mechanical characteristics, motivating the design of bionic structures with similar features. Therefore, this paper proposed a novel skeleton-reinforced neural style transfer assisted topology optimization (SNST-TO) method that integrates density-based topology optimization with a convolutional neural network to impose stylistic feature constraints, while rigorously controlling the minimum length scale using a structural skeleton. The core of this method is the incorporation of geometric skeleton information into the topology optimization process, which prevents unmanufacturable structural features by relying on geometric knowledge rather than solely on pixel similarity. The influence of the key parameters in the algorithm were deeply studied through a series of numerical examples, and the effectiveness and the robustness of the SNST-TO method were completely proved. Furthermore, the dragonfly-like wing structures were designed using the proposed SNST-TO method and commercial software ABAQUS under uniform boundary conditions for clear comparison. Especially, these designs were fabricated using fused deposition modeling additive manufacturing technology and tested through compression experiments in both spanwise and chordwise directions. Results show that the bionic dragonfly wing structure designed using the proposed algorithm outperforms the ABAQUS-optimized structure in mechanical performance, with enhanced spanwise and chordwise load capacities. The findings show that the SNST-TO method facilitates the design of lightweight, load-bearing dragonfly-like wing structures, with potential applications in creating biomimetic structures for other organisms.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"112 ","pages":"Article 105631"},"PeriodicalIF":4.4,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143552137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonlinear free vibration of sandwich beam with data-driven inverse-designed auxetic core based on deep learning","authors":"Xi Fang,&nbsp;Hui-Shen Shen,&nbsp;Hai Wang","doi":"10.1016/j.euromechsol.2025.105626","DOIUrl":"10.1016/j.euromechsol.2025.105626","url":null,"abstract":"<div><div>This paper presents a novel data-driven inverse design approach for auxetic sandwich beams using a deep generative model (DGM). By integrating a conditional estimator with enhanced loss backpropagation, the DGM can produce 3D truss auxetic unit cells exhibiting the desired negative Poisson's ratio, which serve as the microstructures for the auxetic core of sandwich beams. Employing finite element analysis and advanced 3D metal printing techniques, both numerical and experimental investigations on the linear and nonlinear free vibration characteristics of the 3D lattice specimens are conducted. Remarkably, the free vibration analysis results demonstrate that auxetic sandwich beams designed with DGM achieve significantly higher natural frequencies than those optimized using common topological approaches. We conclude that the proposed DGM-based inverse design methodology holds substantial promise within the field of sandwich structure design. The parametric studies are carried out and the numerical results reveal that factors such as the functionally graded configuration of the core, the facesheet-to-core thickness ratio, boundary conditions, and thermal environments critically influence both linear and nonlinear vibration characteristics of the DGM-engineered sandwich beams.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"112 ","pages":"Article 105626"},"PeriodicalIF":4.4,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spectra and pseudospectra in the evaluation of material stability in phase field schemes","authors":"Michele Benzi ,&nbsp;Daniele La Pegna ,&nbsp;Paolo Maria Mariano","doi":"10.1016/j.euromechsol.2025.105613","DOIUrl":"10.1016/j.euromechsol.2025.105613","url":null,"abstract":"<div><div>We consider the dynamics of bodies with ‘active’ microstructure described by vector-valued phase fields. For waves with time-varying amplitude, the associated evolution equation involves a matrix that can be non-normal, depending on the constitutive choices adopted for the microstructural actions associated with the considered phase field. The occurrence of non-normality requires to look at the pseudospectrum of the considered matrix, namely the set of all possible eigenvalues of matrices in a <span><math><mi>ɛ</mi></math></span>-neighborhood of the matrix itself, because the eigenvalues of non-normal matrices can be very sensitive to small perturbations and therefore the spectral analysis alone would not be sufficient to distinguish with certainty between stable and unstable behavior. We develop the relevant analyses in the case of quasicrystals for which the values of some constitutive parameters are not known or are uncertain from an experimental point of view, a circumstance suggesting parametric analyses. We find circumstances in which the pseudospectra obtained by means of the so-called structured perturbations predict instability when, instead, the spectral analysis indicates stability.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"112 ","pages":"Article 105613"},"PeriodicalIF":4.4,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143518941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Error propagation from microstructure changes to apparent stiffness in 2D biphase matrix-inclusion composites","authors":"Anna Gorgogianni ,&nbsp;Tanguy Ramanantsoavina ,&nbsp;Chloé Arson","doi":"10.1016/j.euromechsol.2025.105612","DOIUrl":"10.1016/j.euromechsol.2025.105612","url":null,"abstract":"<div><div>The representation of material microstructure in most existing analytical homogenization models is condensed into a set of well-known “classical” microstructure descriptors, such as the volume fraction and morphology of the individual phases of a composite. This study considers an enriched set of micro descriptors, containing both those “classical” descriptors as well as “non-classical” descriptors which quantify the spatial correlations of any two given micro material points inside a random heterogeneous material. We focus on 2D composites consisting of a matrix with embedded inhomogeneities (or inclusions) of random spatial arrangement. Both phases are treated as homogeneous, linearly elastic and isotropic. Starting from a rich database of reference microstructures, new datasets of perturbed microstructures are created, by inducing changes emulating the physical processes of inclusion nucleation and growth. All microstructures are characterized using the enriched set of micro descriptors, while their apparent stiffness tensor is computed numerically with the finite element (FE) method. A sensitivity analysis between the changes of the micro descriptors and corresponding changes of the apparent stiffness tensor reveals that the “non-classical” descriptors are consistently highly important to the macroscopic behavior. This suggests that enhanced homogenization models, made dependent on the identified pertinent “non-classical” micro descriptors, could be of higher predictive capability than existing approaches.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"112 ","pages":"Article 105612"},"PeriodicalIF":4.4,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calibration of non-local damage models from full-field measurements: Application to discrete element fields","authors":"Louis Védrine ,&nbsp;Flavien Loiseau ,&nbsp;Cécile Oliver-Leblond ,&nbsp;Rodrigue Desmorat","doi":"10.1016/j.euromechsol.2025.105611","DOIUrl":"10.1016/j.euromechsol.2025.105611","url":null,"abstract":"<div><div>Continuous damage models are increasingly used in numerical simulations to design structures, but their local formulations are sensitive to mesh size and present localization of strains in an infinitely thin region. To overcome these problems non-local damage models and related regularization methods, have been developed introducing a characteristic/internal length, thus avoiding pathological mesh dependence. Those methods make the damage evolution depends on the mechanical quantities at the current material point (local) and its neighborhood (non-local).</div><div>Existing approaches to calibrate the internal length use global quantities in the calibration process, although local data is now becoming accessible (<em>e.g.</em>, using digital image correlation). In this study, we investigate the use of full-field displacement measurements an propose a new methodology for calibrating a non-local damage model based on local field measurements and we apply it to calibrate the Eikonal Non-local Gradient (ENL-G) approach from the measured strain and damage field. After detailing the calibration procedure, we then apply it on a simple ideal case. We illustrate, and analyze the robustness of the calibration procedure with respect to the choice of evolution law and measurement noise of the proposed calibration method. To confront the procedure to a more realistic case, we employed a 2D beam-particle model. This discrete model is first identified with respect to the size and shape effect based on one of the comprehensive experimental data sets available in the literature, including four shapes with three sizes each. Then, it is used to generate a “reference” evolution of the damage and strain fields in beams of different sizes subjected to uniaxial tension.</div><div>The parameters of the discrete model used have been calibrated to represent the scale and size effects, giving a very good representation of the experiments. We also illustrate the evolution of non-local interactions in the Eikonal approach using Green functions. Finally, the application of the calibration procedure shows that it is possible to determine the internal length of the non-local problem studied as well as the damage evolution law and its parameters. The outcomes of this study contribute to shed light on a new methodology to identify non-local damage models based on full-field measurements, and call for experimental size effect campaign with displacement field.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"112 ","pages":"Article 105611"},"PeriodicalIF":4.4,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143519618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Corrigendum to ‘Fast and robust RSDM shakedown solutions of structures under cyclic variation of loads and imposed displacements’ [Eur. J. Mech. / A Solids 95 (2022) 1–19/104657]","authors":"K.V. Spiliopoulos,&nbsp;I.A. Kapogiannis","doi":"10.1016/j.euromechsol.2025.105618","DOIUrl":"10.1016/j.euromechsol.2025.105618","url":null,"abstract":"","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"111 ","pages":"Article 105618"},"PeriodicalIF":4.4,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spinodal decomposition-inspired metamaterial: Tailored homogenized elastic properties via the dimensionless Cahn-Hilliard equation","authors":"B. Mandolesi,&nbsp;C. Iandiorio,&nbsp;V.G. Belardi,&nbsp;F. Vivio","doi":"10.1016/j.euromechsol.2025.105615","DOIUrl":"10.1016/j.euromechsol.2025.105615","url":null,"abstract":"<div><div>Metamaterials are increasingly gaining attention due to their ability to exhibit exceptional properties through architectural design. Among these, spinodal topologies, inspired by minimal surface structures, represent a novel class derived from the spinodal decomposition process occurring in certain metal alloys. In metamaterials research, the spinodal decomposition process is typically approximated using statistical methods, such as the superposition of Gaussian random fields, which are only valid during the initial stages of the phenomenon. In this study, we advance the exploration of metamaterials inspired by spinodal decomposition by addressing the full nonlinear dynamic evolution governed by the Cahn-Hilliard partial differential equation (PDE). While solving this nonlinear PDE at the natural scales of spinodal decomposition usually demands <em>ad hoc</em> algorithms, our approach focuses on scales orders of magnitude larger—those relevant to the production of metamaterials. This scale adjustment allows us to employ a straightforward finite difference algorithm, which is computationally efficient and well-suited to the structural scales of interest. To design metamaterials with tailored elastic properties, we solve the Cahn-Hilliard equation in its dimensionless form, governed by two key dimensionless parameters. The solution fields generated are then transformed into CAD models via a dedicated algorithm, enabling subsequent finite element analysis (FEA) to extract the homogenized elastic properties of the resulting structures. Our analysis investigates how variations in the two dimensionless parameters influence the anisotropic elastic properties of the metamaterial unit-cell. By constructing response surfaces for these properties, we enable a reverse homogenization approach, allowing to design materials with targeted mechanical characteristics. This capability offering precise control over the elastic behavior of metamaterials, of interest in the field of material design. Finally, numerical and experimental validations demonstrate the accuracy of the proposed homogenization framework in predicting displacement fields, even for the complex topologies of spinodal decomposition-inspired metamaterial.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"112 ","pages":"Article 105615"},"PeriodicalIF":4.4,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143529451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploiting flexi-rigid behaviour for complex insertion in limited spaces: Towards a flexi-gripper for heavy objects","authors":"Oliver Jorg,&nbsp;Livio Baccelli,&nbsp;Gualtiero Fantoni","doi":"10.1016/j.euromechsol.2025.105614","DOIUrl":"10.1016/j.euromechsol.2025.105614","url":null,"abstract":"<div><div>This paper introduces a novel two-phase gripper that exploits a flexible be-haviour during actuation and is rigid during grasping and handling. It uses form closure but keeps the footprint at the minimum, thus allowing complex insertions in limited spaces. The main advantages of the gripper are its capability of grasping fragile objects with different shapes, sizes and weights, its low footprint and simple architecture (low number of degrees of freedom), as well as the easy actuation. The gripper has been designed as the end effector of a robot for cores manipulation in casting moulds in steel industry. Indeed, in foundry the casting operation takes place pouring steel in a mould where fragile sand cores plugs are delicately and precisely placed. The gripper is based on a rigid flexible beam, that is flexible in one direction and becomes rigid in the opposite one, so it bends and curves with almost no force in a direction but behaves like a beam in the other one. When approaching it exploits the flexibility to wrap the core, then, thanks to an engagement and by exploiting the weight of the object, it acts as a rigid beam. The paper illustrates how the gripper is conceived and modelled, and a prototype developed, tested and evaluated. The prototype showed a very good adaptability to different object shapes and sizes.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"112 ","pages":"Article 105614"},"PeriodicalIF":4.4,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143463478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hexagonal element-based topology optimization of dual-axial compliant mechanisms with decoupled kinematics","authors":"Dongpo Zhao ,&nbsp;Haofeng Xu ,&nbsp;Hanheng Du ,&nbsp;Zhiwei Zhu","doi":"10.1016/j.euromechsol.2025.105617","DOIUrl":"10.1016/j.euromechsol.2025.105617","url":null,"abstract":"<div><div>Compliant mechanisms are widely applied in fast-tool-servo machining and micro/nano-positioning devices. However, for multi-degree-of-freedom mechanisms, designing them is a multi-objective, multi-constraint problem where multiple factors need to be considered, such as large stroke, nanometer-level positioning accuracy, and static failure. Currently, traditional design methods may not be able to comprehensively address these factors. To solve these problems, this study proposes a topology optimization-based design method to develop a compliant mechanism with fully decoupled kinematics and two degrees of freedom, where a hexagonal element mesh with Wachspress shape functions is utilized. Besides, a coupling constraint formulation is designed to avoid the motion coupling in the input end and output end of the compliant mechanism and enhance positioning accuracy. Furthermore, a normalized p-norm stress method is used to restrict the compliant mechanism's maximum stress, which aims to prevent static failure and enhance its reliability. Finally, a dual-axial compliant mechanism with decoupled kinematics, as the numerical example, is designed by the proposed topology optimization method, and its performance specifications are verified by the finite element simulation, which demonstrates the effectiveness and superiority of the proposed topology optimization method on the design of the compliant mechanism.</div></div>","PeriodicalId":50483,"journal":{"name":"European Journal of Mechanics A-Solids","volume":"112 ","pages":"Article 105617"},"PeriodicalIF":4.4,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}