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SSRN 2024年

作者： Liu, Nianqi Yuan, Zifeng HEDPS Center for Applied Physics and Technology Department of Mechanics and Engineering Science Peking University Beijing100871 China State Key Laboratory for Turbulence and Complex Systems Peking University Beijing100871 China

This manuscript proposes a novel multiscale multi-phase-field method based on reduced-order-homogenization (ROH) approach to investigate the damage initiation and crack evolution for the composites, namely the Ms-PFM. Unlike many existing multi-phase-field methods that are applied to fiber reinforced composites which consist of two different phases, the Ms-PFM can handle any number of phase fields. In the Ms-PFM, each phase of the composite has its phase field. The composite's overall response is then obtained by averaging and homogenization approaches through the ROH framework in order to obtain the macroscopic stress and consistent material moduli. In the present work, we derive the governing equations in terms of the displacement field and each phase field. Through the ROH and the Francfort-Marigo variational principle, we can obtain the governing elliptical partial differential equation for each phase field regarding the stress states of different phases of the composites. Through the Ms-PFM, we can identify the damage mechanism at the microscale and simultaneously predict the macroscale load-deformation response. The corresponding weak form is derived, and the numerical algorithm through the finite element method is derived as well. Finally, several sets of numerical examples are adopted to verify the Ms-PFM. The damage evolution predicted by the Ms-PFM shows good agreement with the experiments. © 2024, The Authors. All rights reserved.

关键词： Numerical methods

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Effect of Filler Content on Flexural and Viscoelastic Properties of Coir Fibers and Argania Nut-shells Reinforced Phenolic Resin Composites

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Journal of Bionic engineering 2022年第6期19卷 1886-1898页

作者： Hala Bensalah Marya Raji Kamal Gueraoui Abdelazziz Khtira Hamid Essabir Rachid Bouhfid Abou el kacem Qaiss Group of Mechanics and Materials Energy Research CenterFaculty of ScienceMohammed V University in Rabat10100RabatMorocco Composites and Nanocomposites Center Moroccan Foundation for Advanced ScienceInnovation and Research(MAScIR)10100RabatMorocco Mohammed Ⅵ Polytechnic University Lot 660 Hay Moulay Rachid43150Ben GuerirMorocco Group of Simulation in Mechanics and Energy Energy Research CenterFaculty of ScienceMohammed Ⅴ University10100RabatMorocco Group of Semiconductors and Environmental Sensor Technologies Energy Research CenterFaculty of ScienceMohammed V University10100RabatMorocco Mechanic Materials and Composites(MMC) Laboratory of Energy EngineeringMaterials and SystemsNational School of Applied Sciences of AgadirIbn Zohr University80000AgadirMorocco

The characteristics of two different kinds of lignocellulosic materials(vegetable fillers)with two morphologies as Argania nut-shells(ANS)particles and Coir Fibers(CF)were used as reinforcement for phenolic resin(Bakelite)in this work,and the composite are studied as a function of filler types,shape,content(10,20,and 30%***)and manufacturing loading force(1500 and 3000 LBs).Compression molding was used to create the composites,which were then evaluated using Scanning electronic microscopy(SEM),Fourier-transform infrared spectroscopy(FTIR),bending,dynamic-mechanical-thermal and rheological *** morphology of broken samples demonstrates that both fillers are well dispersed and *** fillers are added to the matrix,the flexural characteristics improve,and the optimal values are attained in the case of Argania *** results showed that the kind and shape of the fillers had a direct influence on the dynamic mechanical characteristics of the composites due to the reinforcement's modulus *** was noticed that,the increment of manufacturing loading force decreased the mechanical and dynamical properties of *** optimum properties obtained indicate that the composites can only be manufactured at low manufacturing loading force(1500 LBs).

关键词： Phenolic resin composites Bionic materials Coir Fibers Argania nut-shells Dynamical mechanical properties Rheological properties

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Electro-mechanically controlled assembly of reconfigurable 3D mesostructures and electronic devices based on dielectric elastomer platforms

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National Science Review 2020年第2期7卷 342-354页

作者： Wenbo Pang Xu Cheng Haojie Zhao Xiaogang Guo Ziyao Ji Guorui Li Yiming Liang Zhaoguo Xue Honglie Song Fan Zhang Zheng Xu Lei Sang Wen Huang Tiefeng Li Yihui Zhang Applied Mechanics Laboratory Department of Engineering Mechanics Tsinghua University Center for Flexible Electronics Technology Tsinghua University School of Microelectronics Soft Membrane Electronic Technology Laboratory Hefei University of Technology Zhejiang Lab State Key Laboratory for Manufacturing and Systems Engineering School of Mechanical Engineering Xi'an Jiaotong University Center for X-Mechanics Zhejiang University

The manufacture of 3D mesostructures is receiving rapidly increasing attention, because of the fundamental significance and practical applications across wide-ranging areas. The recently developed approach of buckling-guided assembly allows deterministic formation of complex 3D mesostructures in a broad set of functional materials, with feature sizes spanning nanoscale to centimeter-scale. Previous studies mostly exploited mechanically controlled assembly platforms using elastomer substrates, which limits the capabilities to achieve on-demand local assembly, and to reshape assembled mesostructures into distinct 3D configurations. This work introduces a set of design concepts and assembly strategies to utilize dielectric elastomer actuators as powerful platforms for the electro-mechanically controlled 3D assembly. Capabilities of sequential, local loading with desired strain distributions allow access to precisely tailored 3D mesostructures that can be reshaped into distinct geometries, as demonstrated by experimental and theoretical studies of30 examples. A reconfigurable inductive–capacitive radio-frequency circuit consisting of morphable 3D capacitors serves as an application example.

关键词： 3D assembly buckling reconfigurable structures dielectric elastomers reconfigurable RF circuits

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Micromechanics of composites with interface effects

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Acta Mechanica Sinica 2022年第4期38卷 1-20,I0001页

作者： Huiling Duan Jianxiang Wang Zhuping Huang State Key Laboratory for Turbulence and Complex Systems Department of Mechanics and Engineering Science.Beijing Innovation Center for Engineering Science and Advanced TechnologyCollege of EngineeringPeking University.Beijing 100871China Center for Applied Physics and Technology Key Laboratory of High Energy Density Physics Simulations and IFSA Collaborative Innovation Center of the Ministry'of EducationPeking UniversityBeijing 100871China

In terfaces that exist in composites greatly influence their mechanical and conductive *** are usually three interface models to characterize the elastic and conductive properties of the interface in *** elastic problems,they are the interface stress model(ISM),linear spring model(LSM),and interphase *** conductive problems,they are the high conducting(HC)interface model,low conducting(LC)interface model,and interphase *** elastic problems with the interface effects,they can be divided into two *** first kind of elastic problem concerns the solution of boundary value problems and aims to predict the effective properties of composites with interface *** second kind of elastic problem concerns the surface/interface stress effects on the elastic properties of nanostructured materials,which is usually characterized by the *** this paper,three aspects in the elastic problems with interface effects are first reviewed,i.e.,equivalent relations among the three interface models,Eshelby formalism,and micromechanical *** emphasis is placed on the ISM to show how classical models can be extended to the nano-scale by supplementing the interface elasticity to the basic equations of the classical elastic ***,the conductive problems of the composites with the interface effects are also reviewed,and the general frameworks for predicting the effective conductivity of the composites are ***,scaling laws depicting the size-dependent elastic and conductive properties of the composites are discussed.

关键词： Interface effect.Micromechanics Composites Effective properties Scaling law

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A comparative analysis for different finite element types in strain-gradient elasticity simulations performed on Firedrake and FEniCS

arXiv

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arXiv 2024年

作者： Sarar, B. Cagri Yildizdag, M. Erden Fabbrocino, Francesco Abali, B. Emek International Research Center on Mathematics and Mechanics of Complex Systems University of L'Aquila L'Aquila Italy Department of Architecture Design and Urban Planning University of Sassari Alghero07041 Italy Faculty of Naval Architecture and Ocean Engineering Istanbul Technical University Istanbul34469 Turkey Department of Engineering Telematic University Pegaso Napoli80143 Italy Department of Materials Science and Engineering Division of Applied Mechanics Uppsala University Box 35 Uppsala751 03 Sweden

The layer-upon-layer approach in additive manufacturing, open or closed cells in polymeric or metallic foams involve an intrinsic microstructure tailored to the underlying applications. Homogenization of such architectured materials creates metamaterials modeled by higher-gradient models, specifically when the microstructure's characteristic length is comparable to the length scale of the structure. In this study, we conduct a comparative analysis of various finite elements methods for solving problems in strain-gradient elasticity. We employ open-source packages from Firedrake and FEniCS. Different finite element formulations are tested: we implement Lagrange, Argyris, Hermite elements, a Hu-Washizu type (mixed) formulation, as well as isogeometric analysis with Non-Uniform Rational B-Splines (NURBS). For the numerical study, we investigate one- and twodimensional problems discussed in the literature of strain-gradient modeling. All developed codes are open-access to encourage research in Finite Element Method (FEM) based computation of generalized continua. Copyright © 2024, The Authors. All rights reserved.

关键词： Microstructure

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Bifurcation Analysis of Incompressible Fluid Flow by a High Order Mesh-Free Indicator with Padé Approximants 15th

Bifurcation Analysis of Incompressible Fluid Flow by a Hi...

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15th International Moroccan Congress of mechanics, CMM 2022

作者： Rammane, M. Mesmoudi, S. Askour, O. Tri, A. Braikat, B. Damil, N. Laboratory of Materials Signals Systems and Physical Modeling Department of Physics Faculty of Sciences Agadir University Ibn Zohr BP 8106 Agadir80000 Morocco Hassan First University of Settat National School of applied Sciences LISA Laboratory Berrechid26100 Morocco Mathematics Computer Science and Communication Systems Laboratory National School of Applied Sciences of Safi Cadi Ayyad University BP 63 Safi Sidi Bouzid46000 Morocco Laboratory of Mechanics Faculty of Sciences Ain Chock Hassan II University of Casablanca Casablanca Morocco Km 7 Route d’El Jadida Casablanca Morocco Laboratory of Engineering and Materials Faculty of Sciences Ben M’sik Hassan II University of Casablanca B.P 7955 Sidi Othman Casablanca Morocco Central Casablanca Complex Systems and Interactions Research Center Green City Bouskoura27182 Morocco

ISBN: (纸本)9783031469725

In this work, a mesh-free indicator is proposed to detect the bifurcation points of incompressible viscous fluid flow in a 2D sudden expansion. This indicator is mainly based on the high order mesh-free algorithm (HO-MFA) to solve the nonlinear problems obtained from the linear stability analysis. The Padé approximants are then used to improve the validity range of the HO-MFA and to determinate the roots of the indicator. The combination of these mathematical tools allows us to determine the zero of the indicator corresponding to the critical point. The Lyapunov-Schmidt reduction is used to search all the bifurcated branches from the critical point. To show the accuracy of our model, comparisons of the obtained results with those of the literature are made. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Linear stability analysis

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Elastic 3D Microelectrodes with Jellyfish-Like Microbumps and Grapping Strips as a Reliable Neural Interface

Elastic 3D Microelectrodes with Jellyfish-Like Microbumps an...

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IEEE International Conference on Micro Electro Mechanical systems

作者： Fanqi Sun Qing Liu Xiaoli You Zekai Liang Kai Xue Jun Guo Minghao Wang Jiahao Wang Kai Tao Honglong Chang Bowen Ji Unmanned System Research Institute Northwestern Polytechnical University Xi’an China Ministry of Education Key Laboratory of Micro/Nano Systems for Aerospace School of Mechanical Engineering Northwestern Polytechnical University Xi’an China Collaborative Innovation Center of Northwestern Polytechnical University Shanghai China Department of Engineering Mechanics Applied Mechanics Laboratory Tsinghua University Beijing China Laboratory of Flexible Electronics Technology Tsinghua University Beijing China College of Electronics and Information Hangzhou Dianzi University Hangzhou China

This work reports an elastic 3D microelectrode array with jellyfish-like microbumps and grapping strips for the first time. The soft silicone microbump wrapped by thin-film polyimide (PI) strips is formed by stress-free premolding and post injection molding. The elastic structure serves as a reliable neural interface to push the microelectrode sites closer to the dura mater for high-quality electrocorticogram (ECoG) recording. Besides, the elastic interface with sufficient mechanical strength can withstand the external pressure from overlay of dental cement or cranial window, thanks to its self-compression capability without debonding of grapping strips or electrochemical degradation. Thus, this bionic structure has advantages to reshape the traditional 2D electrodes to 3D for more durable neural recording, and avoid the unbuffered contact of the overlaid sealing cement or window to the underlying soft tissue.

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A Simple Quantitative Model of Neuromodulation. Part I: Ion Flow Through Neural Ion Channels

arXiv

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arXiv 2023年

作者： Werneck, Linda Han, Mertcan Yildiz, Erdost Keip, Marc-André Sitti, Metin Ortiz, Michael Institute of Applied Mechanics University of Stuttgart Stuttgart Germany Physical Intelligence Department Max Planck Institute for Intelligent Systems Stuttgart Germany Institute for Biomedical Engineering ETH Zurich Zurich Switzerland School of Medicine College of Engineering Koc University Istanbul Turkey Division of Engineering and Applied Science California Institute of Technology PasadenaCA United States Hausdorff Center for Mathematics University of Bonn Bonn Germany

We develop a simple model of ionic current through neuronal membranes as a function of membrane potential and extracellular ion concentration. The model combines a simplified Poisson-Nernst-Planck (PNP) model of ion transport through individual mechanosensitive ion channels with channel activation functions calibrated from ad hoc in-house experimental data. The simplified PNP model is validated against bacterial Gramicidin A ion channel data. The calibrated model accounts for the transport of calcium, sodium, potassium, and chloride and exhibits remarkable agreement with the experimentally measured current-voltage curves for the differentiated human neural cells. All relevant data and code related to the ion flow models are available at [1]. © 2023, CC BY.

关键词： Ions

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Atomic-scale simulations for lithium dendrite growth driven by strain gradient

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applied Mathematics and mechanics(English Edition) 2020年第4期41卷 533-542页

作者： Gao XU Feng HAO Jiawang HONG Daining FANG State Key Laboratory for Turbulence and Complex Systems&Center for Applied Physics and Technology College of EngineeringPeking UniversityBeijing 100871China Department of Engineering Mechanics Shandong UniversityJinan 250100China School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China

Dendrite formation is a major obstacle, e.g., capacity loss and short circuit,to the next-generation high-energy-density lithium(Li)-metal batteries. The development of successful Li dendrite mitigation strategies is impeded by an insu?cient understanding in Li dendrite growth mechanisms. The Li-plating-induced internal stress in Li-metal and its e?ects on dendrite growth have been widely studied, but the underlying microcosmic mechanism is elusive. In the present study, the role of the plating-induced stress in dendrite formation is analyzed through ?rst-principles calculations and ab initio molecular dynamic(AIMD) simulations. It is shown that the deposited Li forms a stable atomic nano?lm structure on the copper(Cu) substrate, and the adsorption energy of Li atoms increases from the Li-Cu interface to the deposited Li surface, leading to more aggregated Li atoms at the interface. Compared with the pristine Li-metal, the deposited Li in the early stage becomes compacted and su?ers the in-plane compressive stress. Interestingly,there is a giant strain gradient distribution from the Li-Cu interface to the deposited Li surface, making the deposited atoms adjacent to the Cu surface tend to press upwards with perturbation and causing the dendrite growth. This provides an insight into the atomicscale origin of Li dendrite growth, and may be useful for suppressing the Li dendrite in Li-metal-based rechargeable batteries.

关键词： lithium(Li)-metal-based battery Li dendrite strain gradient depositing

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Consistent lifting relations for the initialization of total-energy double-distribution-function kinetic models

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Physical Review E 2023年第6期108卷 065301-065301页

作者： Yiming Qi (岐亦铭) Lian-Ping Wang (王连平) Zhaoli Guo (郭照立) Shiyi Chen (陈十一) State Key Laboratory for Turbulence and Complex Systems College of engineering Peking University Beijing 100871 China Guangdong Provincial Key Laboratory of Turbulence Research and Applications Center for Complex Flows and Soft Matter Research and Department of Mechanics and Aerospace Engineering Southern University of Science and Technology Shenzhen Guangdong 518055 China Institute of Interdisciplinary Research for Mathematics and Applied Science Huazhong University of Science and Technology Wuhan Hubei 430074 China Eastern Institute for Advanced Study Eastern Institute of Technology Ningbo Zhejiang 315200 China

A lifting relation connecting the distribution function explicitly with the hydrodynamic variables is necessary for the Boltzmann equation-based mesoscopic approaches in order to correctly initialize a nonuniform hydrodynamic flow. We derive two lifting relations for Guo et al.'s total-energy double-distribution-function (DDF) kinetic model [Z. L. Guo et al., Phys. Rev. E 75, 036704 (2007)], one from the Hermite expansion of the conserved and nonconserved moments, and the second from the O(τ) Chapman-Enskog (CE) approximation of the Maxwellian exponential equilibrium. While both forms are consistent to the compressible Navier-Stokes-Fourier system theoretically, we stress that the latter may introduce numerical oscillations under the recently optimized discrete velocity models [Y. M. Qi et al., Phys. Fluids 34, 116101 (2022)], namely a 27 discrete velocity model of the seventh-order Gauss-Hermite quadrature (GHQ) accuracy (D3V27A7) for the velocity field combined with a 13 discrete velocity model of the fifth-order GHQ accuracy (D3V13A5) for the total energy. It is shown that the Hermite-expansion–based lifting relation can be alternatively derived from the latter approach using the truncated Hermite-polynomial equilibrium. Additionally, a relationship between the order of CE expansions and the truncated order of Hermite equilibria is developed to determine the minimal order of a Hermite equilibria required to recover any multiple-timescale macroscopic system. Next, three-dimensional compressible Taylor-Green vortex flows with different initial conditions and Ma numbers are simulated to demonstrate the effectiveness and potential issues of these lifting relations. The Hermite-expansion–based lifting relation works well in all cases, while the Chapman-Enskog-expansion–based lifting relation may produce numerical oscillations and a theoretical model is developed to predict such oscillations. Furthermore, the corresponding lifting relations for Qi et al.'s total energy

关键词： Three-dimensional turbulence Turbulence simulations Direct numerical simulations Lattice-Boltzmann methods

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