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  • Open Access


    Topology Optimization of Metamaterial Microstructures for Negative Poisson’s Ratio under Large Deformation Using a Gradient-Free Method

    Weida Wu, Yiqiang Wang, Zhonghao Gao, Pai Liu*

    CMES-Computer Modeling in Engineering & Sciences, Vol.139, No.2, pp. 2001-2026, 2024, DOI:10.32604/cmes.2023.046670

    Abstract Negative Poisson’s ratio (NPR) metamaterials are attractive for their unique mechanical behaviors and potential applications in deformation control and energy absorption. However, when subjected to significant stretching, NPR metamaterials designed under small strain assumption may experience a rapid degradation in NPR performance. To address this issue, this study aims to design metamaterials maintaining a targeted NPR under large deformation by taking advantage of the geometry nonlinearity mechanism. A representative periodic unit cell is modeled considering geometry nonlinearity, and its topology is designed using a gradient-free method. The unit cell microstructural topologies are described with the material-field series-expansion (MFSE) method. The… More >

  • Open Access


    Dynamic Testing of Elastic Modulus, Shear Modulus, and Poisson’s Ratio of Bamboo Scrimber

    Xiaoyu Gu1, Linbi Chen2, Seithati Mapesela3, Zheng Wang1,*, Aijin Zhou4

    Journal of Renewable Materials, Vol.11, No.12, pp. 4197-4210, 2023, DOI:10.32604/jrm.2023.028768

    Abstract The bamboo scrimber is an anisotropic material. The elastic constant values of the bamboo scrimber specimens measured by the dynamic and static methods are consistent, and the dynamic test method has the advantages of rapidity, simplicity, good repeatability, and high precision. Bamboo scrimber has strong potential as a building material, and its elastic constant is an important index to measure its mechanical properties. To quickly, simply, non-destructively, and accurately detect the elastic constant of the bamboo scrimber, they were dynamically tested by the free plate transient excitation method and cantilever plate torsional vibration method. The static four-point bending method was… More >

  • Open Access


    Research on Dynamic and Static Test Methods for Evaluating the Poisson’s Ratio of Oriented Strand Board

    Yuhao Zhou, Yuhang He, Zhaoyu Shen, Zheng Wang*

    Journal of Renewable Materials, Vol.10, No.12, pp. 3459-3476, 2022, DOI:10.32604/jrm.2022.021251

    Abstract In this article, dynamic method and static method of testing Poisson’s ratio of OSB (Oriented Strand Board) were proposed. Through modal and static numerical analyses, the position where the transverse stress is equal to zero was determined. The binary linear regression method was applied to express the gluing position of the strain gauge as a relational expression that depended on the length-width ratio and width-thickness ratio of the cantilever plate. Then the longitudinal and transverse Poisson’s ratios of OSB were measured by the given dynamic and static methods. In addition, the test results of OSB Poisson’s ratio were analyzed with… More >

  • Open Access


    Topology and Shape Optimization of 2-D and 3-D Micro-Architectured Thermoelastic Metamaterials Using a Parametric Level Set Method

    Ellie Vineyard1, Xin-Lin Gao2,*

    CMES-Computer Modeling in Engineering & Sciences, Vol.127, No.3, pp. 819-854, 2021, DOI:10.32604/cmes.2021.015688

    Abstract 2-D and 3-D micro-architectured multiphase thermoelastic metamaterials are designed and analyzed using a parametric level set method for topology optimization and the finite element method. An asymptotic homogenization approach is employed to obtain the effective thermoelastic properties of the multiphase metamaterials. The -constraint multi-objective optimization method is adopted in the formulation. The coefficient of thermal expansion (CTE) and Poisson’s ratio (PR) are chosen as two objective functions, with the CTE optimized and the PR treated as a constraint. The optimization problems are solved by using the method of moving asymptotes. Effective isotropic and anisotropic CTEs and stiffness constants are obtained… More >

  • Open Access


    Inverse Analysis of Viscoelastic Material Properties Considering Time- and Temperature-Dependence of Poisson’s Ratio

    Shotaro Taguchi1,*, Satoru Yoneyama2

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.23, No.1, pp. 20-20, 2021, DOI:10.32604/icces.2021.08535

    Abstract This study proposes a method for identifying viscoelastic properties that considers time- and temperature dependence of Poisson's ratio using inverse analysis. In this method, displacement distribution, which are input values of inverse analysis, is measured by digital image correlation [1], and unknown material properties are determined using the virtual fields method [2]. This method targets plane stress condition and the Poisson's ratio of the viscoelastic body depends on the time and temperature [3]. This study focuses on the correspondence law and proposes a method for calculating stresses considering time- and temperature dependence of Poisson's ratio. In-plane strains are measured and… More >

  • Open Access


    Topological Design of Microstructures of Materials Containing Multiple Phases of Distinct Poisson’s Ratios

    Kai Long1,*, Xiaoyu Yang1, Nouman Saeed1, Zhuo Chen1, Yi Min Xie2

    CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.1, pp. 293-310, 2021, DOI:10.32604/cmes.2021.012734

    Abstract A methodology for achieving the maximum bulk or shear modulus in an elastic composite composed of two isotropic phases with distinct Poisson’s ratios is proposed. A topology optimization algorithm is developed which is capable of nding microstructures with extreme properties very close to theoretical upper bounds. The effective mechanical properties of the designed composite are determined by a numerical homogenization technique. The sensitivities with respect to design variables are derived by simultaneously interpolating Young’s modulus and Poisson’s ratio using different parameters. The so-called solid isotropic material with penalization method is developed to establish the optimization formulation. Maximum bulk or shear… More >

  • Open Access


    Data-Driven Structural Design Optimization for Petal-Shaped Auxetics Using Isogeometric Analysis

    Yingjun Wang1, Zhongyuan Liao1, Shengyu Shi1, *, Zhenpei Wang2, *, Leong Hien Poh3

    CMES-Computer Modeling in Engineering & Sciences, Vol.122, No.2, pp. 433-458, 2020, DOI:10.32604/cmes.2020.08680

    Abstract Focusing on the structural optimization of auxetic materials using data-driven methods, a back-propagation neural network (BPNN) based design framework is developed for petal-shaped auxetics using isogeometric analysis. Adopting a NURBS-based parametric modelling scheme with a small number of design variables, the highly nonlinear relation between the input geometry variables and the effective material properties is obtained using BPNN-based fitting method, and demonstrated in this work to give high accuracy and efficiency. Such BPNN-based fitting functions also enable an easy analytical sensitivity analysis, in contrast to the generally complex procedures of typical shape and size sensitivity approaches. More >

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