Article
Mechanics
Praveen Ailawalia, Deepali Gupta
Summary: This research article investigates deformation in a non-homogeneous orthotropic micropolar medium and analyzes the effect of anisotropy on physical quantities using normal mode analysis and numerical computations.
MECHANICS BASED DESIGN OF STRUCTURES AND MACHINES
(2023)
Article
Materials Science, Multidisciplinary
Natsuki Mukai, Andrey O. Leonov
Summary: This study revisits the theoretical phase diagram of a two-dimensional chiral magnet and focuses on the phase transition between the cycloid and the hexagonal skyrmion lattice. The research highlights the dynamics of merons, which possess fractional topological charges, and their nonreciprocal current-driven behavior. The study also examines the ordering of skyrmions into hexagonal and square lattices and reveals the stability of the square lattice as a saddle point state.
Article
Mechanics
M. E. Fares, M. G. Salem, Doaa Atta, M. Kh. Elmarghany
Summary: A mixed variational principle is established for the micropolar elasticity theory, treating displacements, microrotations, force stresses, and couple stresses as independent fields. This principle helps to overcome inconsistencies between simple kinematic assumptions and boundary conditions and presents an improved 2D model for micropolar plates. Bending and free vibration applications are studied, considering different edge conditions and assessing the importance of normal strain and microrotation effects.
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
(2023)
Article
Engineering, Mechanical
Zekun Wang, Yufeng Xing, Gen Li
Summary: The extended separation-of-variable method proposed in this work provides more accurate modes and frequencies for the vibrating problem of orthotropic plates based on 3-D elasticity theory. Numerical experiments validate the accuracy of the present solutions.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Materials Science, Multidisciplinary
Zeyang Chi, Jinxing Liu, Ai Kah Soh
Summary: The homogenization procedure of planar chiral structures within micropolar theory predicts constitutive behaviors, demonstrating a strong coupling between stretch and shear in square lattices. Microstructural geometric parameters influence the homogenized Young's modulus and Poisson's ratio. Micropolar characteristic lengths are given explicitly in terms of microstructural parameters for adjusting size effects.
MECHANICS OF MATERIALS
(2021)
Article
Engineering, Mechanical
Lihao Huang, Huang Yuan, Haiyan Zhao
Summary: Lattice metamaterials are increasingly used in weight-critical applications, and additive manufacturing technology provides more design freedoms. A new homogenization method based on finite element methods was proposed for accurate modeling of the mechanical behavior of complex microstructures. The mapping relation between lattice and finite element mesh, as well as edge effects, were clarified and modeled. The homogenization approach showed high numerical accuracy and outperformed the classical continuum model.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Materials Science, Multidisciplinary
Swapneel Amit Pathak, Riccardo Hertel
Summary: The study on FeGe nanospheres reveals a variety of equilibrium magnetization states, which could be described by a phase diagram. This diversity may offer useful features for multistate memory devices. The negligible magnetodipolar interaction in these systems suggests potential high-density arrangements of particles without unwanted coupling.
Article
Mathematics, Applied
M. Kohansal-Vajargah, R. Ansari, M. Faraji-Oskouie, M. Bazdid-Vahdati
Summary: Based on the micropolar theory, a two-dimensional element is proposed to describe the free vibration response of structures. In this study, a 2D formulation is developed within the ABAQUS finite element software. The effect of micropolar on the vibration behavior of 2D structures with arbitrary shapes is studied, showing a dominant role of micro-inertia and a decrease in frequencies by considering micropolar effects. It was also found that there is a considerable discrepancy between predicted micropolar and classical frequencies at small scales, but this difference decreases as the side length-to-length scale ratio becomes large.
APPLIED MATHEMATICS AND MECHANICS-ENGLISH EDITION
(2021)
Article
Engineering, Civil
M. Kohansal-Vajargah, R. Ansari
Summary: The paper presents a free vibration analysis of three-dimensional micropolar structures with different geometries and studies the effects of length scale parameter on the dimensionless natural frequencies of micropolar structures with various geometries.
THIN-WALLED STRUCTURES
(2021)
Article
Multidisciplinary Sciences
Yangyang Chen, Xiaopeng Li, Colin Scheibner, Vincenzo Vitelli, Guoliang Huang
Summary: Mechanical metamaterials exhibit unique properties not found in ordinary materials, such as active metamaterials with self-sensing characteristics demonstrated by the authors. These active metamaterials can convert electrical energy into mechanical work, and their odd modulus allows for localized vibrational modes at sample boundaries.
NATURE COMMUNICATIONS
(2021)
Article
Mechanics
Jianfei Yao, Rujie Sun, Fabrizio Scarpa, Chrystel Remillat, Yu Gao, Yongfei Su
Summary: This study investigates the in-plane uniaxial tensile mechanical properties of two-dimensional graded rectangular perforations metamaterials using numerical homogenization finite element approaches benchmarked by experimental results. The metamaterial configuration is based on graded patterns of center-symmetric perforated cells that can exhibit an auxetic behavior. The overall stiffness behavior of the graded perforated metamaterial plates features a higher degree of compliance that depends on both the geometries of the cells of the graded areas and the graded pattern used.
COMPOSITE STRUCTURES
(2021)
Article
Mathematics, Applied
Alexis Bejar-Lopez, Cleyton Cunha, Juan Soler
Summary: This paper examines the interaction between microstructures and the appearance or persistence of singular configurations in the Cauchy problem for the two-dimensional model of incompressible micropolar fluids. Through integral techniques, the existence of weak solutions local or global in time is established, and the uniqueness and stability of these solutions is analyzed.
PHYSICA D-NONLINEAR PHENOMENA
(2022)
Article
Mechanics
Tiantian Li, Yaning Li
Summary: The anisotropic elastic mechanical properties of a family of single material chiral mechanical metamaterials were systematically explored, and an integrated constitutive model was developed to quantify the anisotropic mechanical properties of the chiral designs with different geometries.
JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME
(2022)
Article
Materials Science, Multidisciplinary
Zhihao Yuan, Zhiming Cui, Jaehyung Ju
Summary: The study establishes a generalized micropolar homogenization method to characterize the elastic constants of chiral and achiral lattices, revealing coupling effects and directional Poisson's ratio properties of different structures. This offers a powerful platform for designing metamaterials by adjusting both anisotropy and chirality through geometric reconfiguration of lattice structures.
MATERIALS & DESIGN
(2021)
Article
Engineering, Civil
C. S. Huang, W. C. Chung
Summary: This study presents, for the first time, analytical solutions based on Fourier series and 3D elasticity for the vibrations of functionally graded material (FGM) rectangular plates. The proposed solutions, validated by comparisons with published results and convergence studies, provide insights into the effects of boundary conditions and material parameters on vibration frequencies.
INTERNATIONAL JOURNAL OF STRUCTURAL STABILITY AND DYNAMICS
(2023)
Article
Physics, Applied
Mingye Zheng, Chung Il Park, Xiaoning Liu, Rui Zhu, Gengkai Hu, Yoon Young Kim
APPLIED PHYSICS LETTERS
(2020)
Article
Multidisciplinary Sciences
Yi Chen, Muamer Kadic, Martin Wegener
Summary: Recent work explored isotropic chiral phonon dispersion relations in cubic crystalline approximants, finding that they have smaller effects compared to highly anisotropic chiral cubic metamaterial crystals. A proposed chiral triclinic metamaterial crystal exhibits larger effects but is more susceptible to fabrication tolerances due to an 'accidental' degeneracy in momentum space.
PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2021)
Article
Materials Science, Multidisciplinary
Yi Chen, Tobias Frenzel, Quan Zhang, Muamer Kadic, Martin Wegener
Summary: A chiral simple-cubic metamaterial crystal exhibiting chiral phonons for all phonon propagation directions in 3D space with nearly isotropic acoustical activity has been successfully designed, offering a blueprint with simple cubic crystal symmetry that is easier to fabricate using 3D additive manufacturing methods. This breakthrough in metamaterial design has been demonstrated through electron micrographs of microstructured samples produced using 3D laser nanoprinting.
PHYSICAL REVIEW MATERIALS
(2021)
Article
Physics, Applied
Hongfei Qu, Xiaoning Liu, Gengkai Hu
Summary: This study introduces a sonic topological insulator using an acoustic fluid of the Willis type, exhibiting the valley Hall effect. The valley Hall phase transition can be triggered by tuning the coupling vector, and the tunability of the valley offset offered by Willis coupling helps achieve equally robust one-way transport for different types of domain walls and wave channels.
APPLIED PHYSICS LETTERS
(2021)
Article
Multidisciplinary Sciences
Yi Chen, Muamer Kadic, Martin Wegener
Summary: The authors introduce beyond-nearest-neighbour interactions as a mechanism for molding the flow of waves in acoustic metamaterials. They find that for strong third-nearest-neighbour interactions, this mechanism allows for engineering roton-like acoustical dispersion relations under ambient conditions.
NATURE COMMUNICATIONS
(2021)
Article
Materials Science, Multidisciplinary
Yu Wei, Xiaoning Liu, Gengkai Hu
Summary: This study investigates the potential of QM materials with four zero eigenvalues in controlling elastic waves and designing devices, and proposes a new type of SH wave polarizer for mode conversion prevention. It opens up a new research direction for exploring the wave properties of QM extremal materials.
MATERIALS & DESIGN
(2021)
Article
Multidisciplinary Sciences
Julio Andres Iglesias Martinez, Michael Fidelis Gross, Yi Chen, Tobias Frenzel, Vincent Laude, Muamer Kadic, Martin Wegener
Summary: The research reports the direct experimental observation of roton-like dispersion relations in two different three-dimensional metamaterials under ambient conditions. Two different experiments using ultrasound and audible frequencies respectively were conducted to identify the roton-like minimum in the dispersion relation associated to a triplet of waves at a given frequency. The work demonstrates that designing interactions in metamaterials beyond the nearest neighbors can open unprecedented experimental opportunities to tailor the lowest dispersion branch.
Article
Engineering, Mechanical
Hongfei Qu, Xiaoning Liu, Gengkai Hu
Summary: This paper explores the coupling tensor in elastic Willis media based on a mass spring model and demonstrates material design with customized Willis coupling for elastic wave control. The homogenization and designability of the model are validated through free wave analysis, and the wave transmission properties across a sandwiched Willis layer are analyzed. Two illustrative examples of asymmetric reflection and wave mode conversion are demonstrated using specifically designed lattice models.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Materials Science, Multidisciplinary
Ming Cai, Xiaoning Liu, Gengkai Hu, Pingzhang Zhou
Summary: This study proposes a method for designing extremal materials using topology optimization techniques, which can design more anisotropic materials and customize the eigenvectors. The effectiveness of the method is verified through numerical examples, and extremal materials with arbitrary values of soft or hard modes can be designed. This research provides an important foundation for exploring the properties of extremal materials.
MATERIALS & DESIGN
(2022)
Article
Physics, Applied
Binghao Zhao, Dongwei Wang, Pingzhang Zhou, Xiaoning Liu, Gengkai Hu
Summary: This study investigates how the elastic anisotropy of materials can achieve both extremely low impedance and high stiffness. A dimensionless quality factor is proposed to comprehensively evaluate the performance on sound insulation and load bearing of anisotropic materials. By optimizing the microstructure, materials with optimized integrated performance on waterborne sound insulation and load bearing are designed. The effectiveness of the optimized material is validated through numerical simulations and comparisons with similar low impedance waterborne sound insulation materials. This study opens up possibilities for designing load-bearing materials with extremely low impedance and controlling low-frequency underwater waves.
PHYSICAL REVIEW APPLIED
(2022)
Article
Chemistry, Multidisciplinary
Yi Chen, Mahmoud A. A. Abouelatta, Ke Wang, Muamer Kadic, Martin Wegener
Summary: Introduces reconfigurable plug-and-play electromagnetic metamaterials, where the building blocks are standard bayonet Neill-Concelman (BNC) connectors and the effective properties are achieved by tailoring local and nonlocal interactions mediated by standard coaxial cables. Demonstrates unprecedented dispersion relations with multiple regions of slow waves and backward waves in the lowest band. Importantly, the dispersion relation of such metamaterials is not limited by causality as in the case of local resonances.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Yi Chen, Jonathan L. G. Schneider, Michael F. Gross, Ke Wang, Sebastian Kalt, Philip Scott, Muamer Kadic, Martin Wegener
Summary: This paper introduces the possibility of unusual roton-like acoustical-phonon dispersion relations in 3D elastic materials based on chiral micropolar effective-medium theory. Firstly, the inverse problem is solved by designing a specific 3D chiral elastic metamaterial structure that follows the effective-medium description. The structure consists of cubic lattice cubes with three translational and three rotational degrees of freedom, coupled by a chiral network of slender rods. The manufactured polymer form of the complex metamaterial is characterized experimentally, and the results are in good agreement with theoretical predictions.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Michael Fidelis Gross, Jonathan Ludwig Guenter Schneider, Yu Wei, Yi Chen, Sebastian Kalt, Muamer Kadic, Xiaoning Liu, Genkai Hu, Martin Wegener
Summary: In classical Cauchy elasticity, 3D materials have six eigenmodes of deformation. Extremal elastic materials are classified based on the number of easy eigenmodes out of these six, leading to hexamode (N=6), pentamode (N=5), tetramode (N=4), trimode (N=3), dimode (N=2), and monomode (N=1) materials. Pentamode metamaterials have attracted significant attention, and in this study, microstructured 3D polymer-based tetramode metamaterials were designed, characterized, and compared to theoretical expectations. The potential application as a compact and broadband polarizer for acoustical phonons at ultrasound frequencies was demonstrated.
ADVANCED MATERIALS
(2023)
Article
Physics, Multidisciplinary
Yi Chen, Ke Wang, Muamer Kadic, Sebastien Guenneau, Changguo Wang, Martin Wegener
Summary: Previous theory and experiment have shown that introducing strong nonlocal interactions in addition to local interactions into metamaterials can lead to unusual wave dispersion relations. In this study, the authors investigate the frequency-dependent acoustical phonon transmission in a slab of nonlocal metamaterial. They find a series of bound states in the continuum and sharp transmission resonances next to sharp transmission minima. The findings are validated by numerical calculations on three-dimensional metamaterial microstructures.
COMMUNICATIONS PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Ke Wang, Yi Chen, Muamer Kadic, Changguo Wang, Martin Wegener
Summary: By introducing a two-dimensional metamaterial platform, we utilize nonlocal effects as a powerful design tool to control the wave properties of metamaterials. The study shows that the lowest band can be engineered by Fourier synthesis, and waves can be transferred from a local metamaterial to a nonlocal metamaterial through a carefully designed transition region.
COMMUNICATIONS MATERIALS
(2022)
