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Search Results (17)
  • Open Access

    ARTICLE

    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… More >

  • Open Access

    PROCEEDINGS

    Multi-Scale Topology Optimization Method Considering Multiple Structural Performances

    Wenjun Chen1, Yingjun Wang1,*

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.3, pp. 1-1, 2023, DOI:10.32604/icces.2023. 09096

    Abstract The rapid development of topology optimization has given birth to a large amount of different topology optimization methods, and each of them can manage a class of corresponding engineering problems. However, structures need to meet a variety of requirements in engineering application, such as lightweight and multiple load-bearing performance. To design composite structures that have multiple structural properties, a new multi-scale topology optimization method considering multiple structural performances is proposed in this paper. Based on the fitting functions of the result set and the bisection method, a new method to determine the weight coefficient is… More >

  • Open Access

    ARTICLE

    Finite Element Simulations on Failure Behaviors of Granular Materials with Microstructures Using a Micromechanics-Based Cosserat Elastoplastic Model

    Chenxi Xiu1,2,*, Xihua Chu2

    CMES-Computer Modeling in Engineering & Sciences, Vol.138, No.3, pp. 2305-2338, 2024, DOI:10.32604/cmes.2023.030194

    Abstract This paper presents a micromechanics-based Cosserat continuum model for microstructured granular materials. By utilizing this model, the macroscopic constitutive parameters of granular materials with different microstructures are expressed as sums of microstructural information. The microstructures under consideration can be classified into three categories: a medium-dense microstructure, a dense microstructure consisting of one-sized particles, and a dense microstructure consisting of two-sized particles. Subsequently, the Cosserat elastoplastic model, along with its finite element formulation, is derived using the extended Drucker-Prager yield criteria. To investigate failure behaviors, numerical simulations of granular materials with different microstructures are conducted using… More >

  • Open Access

    PROCEEDINGS

    Multi-Scale Topology Optimization Method Considering Multiple Structural Performances

    Wenjun Chen1, Yingjun Wang1,*

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.26, No.2, pp. 1-1, 2023, DOI:10.32604/icces.2023.09095

    Abstract The rapid development of topology optimization has given birth to a large amount of different topology optimization methods, and each of them can manage a class of corresponding engineering problems. However, structures need to meet a variety of requirements in engineering application, such as lightweight and multiple load-bearing performance. To design composite structures that have multiple structural properties, a new multi-scale topology optimization method considering multiple structural performances is proposed in this paper. Based on the fitting functions of the result set and the bisection method, a new method to determine the weight coefficient is… More >

  • Open Access

    PROCEEDINGS

    Magnetic Micropillar Structures for Programmable and Reprogrammable Actuation

    Ke Ni1, Zhengzhi Wang1,2,3,*

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.25, No.4, pp. 1-2, 2023, DOI:10.32604/icces.2023.09248

    Abstract Stimuli-responsive micropillar structures that can perform dynamics and reversible deformations according to external stimuli have been applied in a wide spectrum of fields, including object manipulation, soft miniature robots, and functional surfaces. However, it remains a challenge to exhibit programmable actuation behaviors for applications that require on-demand deformation response. Herein, a two-step photomask-assisted template casting technique is developed to fabricate a hybrid magnetic micropillar array for programmable actuation. By modulating the spatial distribution of the magnetic nanoparticles within the elastomer micropillars, the bending deformations of the micropillars with different particle distributions can vary near one… More >

  • Open Access

    PROCEEDINGS

    Microstructures and Nanomechanical Properties of Additively Manufactured Metallic Stents

    Enzoh Langi1, Liguo Zhao2,*

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.25, No.3, pp. 1-1, 2023, DOI:10.32604/icces.2023.010163

    Abstract Additive manufacturing emerges as an innovative technology to fabricate medical stents used to treat blocked arteries. However, there is a lack of study of underlying microstructure and mechanical properties of additively manufactured stent. In this work, additively manufactured 316L stainless steel stent was investigated, with electrochemical polishing being used to improve the surface finish. Microstructural characterisation was carried out using optical microscopy, scanning electron microscopy, and electron backscatter diffraction. The hardness and elastic modulus were measured using Berkovich nanoindentation, with an emphasis on the effect of grain orientation. In addition, spherical nanoindentation was used to… More >

  • Open Access

    PROCEEDINGS

    Interfacial Delamination in High-Temperature Coatings with Segmented Microstructures

    Biao Li1,*

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.25, No.1, pp. 1-2, 2023, DOI:10.32604/icces.2023.09818

    Abstract High-temperature coatings are extensively used in aircraft engines and industrial gas turbines to protect hot-section components from harsh operating environments [1]. Representative high-temperature coatings include thermal barrier coatings and environmental barrier coatings, which are applied to substrates made of superalloy and ceramic matrix composites, respectively. The durability of the coatings is of significant importance for the structural integrity of the components [2-4]. A segmented microstructure was widely used to improve the coatings' durability. A network of through-thickness vertical cracks is introduced into the outer layer of the coatings, which increases the compliance of the coatings… More >

  • Open Access

    ARTICLE

    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… More >

  • Open Access

    ABSTRACT

    Deformation analysis techniques applied to microstructures and micro-device

    Zhanwei Liu, Huimin Xie, Fulong Dai

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.18, No.3, pp. 95-96, 2011, DOI:10.3970/icces.2011.018.095

    Abstract The mechanical behaviors of microstructures and micro devices have drawn the attention from researchers on materials and mechanics recently. To understand the rule of these behaviors, the deformation measurement techniques with micro/nanometer sensitivity and spatial resolution are required. In this report, a geometric phase analysis technique, SEM scanning moirAC method, digital phase moirAC method based on gratings and a micro-marker identification method are introduced to meet the deformation evaluation requirement of MEMS. The geometric phase analysis technique is performed on the basis of regular gratings, instead of natural atom lattice. The regular gratings with a… More >

  • Open Access

    ABSTRACT

    Crack propagation characteristics of a high-ductility steel with layered and graded microstructures

    A.Y.Chen, J. Lu

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.2, pp. 45-46, 2011, DOI:10.3970/icces.2011.020.045

    Abstract The structural reliability of many brittle materials such as nanomaterials relies on the occurrence of intergranular, as opposed to transgranular, fracture in order to induce toughening by crack bridging. The current work examines the role of interface strength and grain size distribution in promoting intergranular fracture in order to maintain high toughening. A layered nanostructural 304SS sheet characterized by periodic distribution of nanocrystalline layers and micron-grained layers with graded grain size evolution has exhibited exceptional properties. The in situ SEM observations illustrate that an intergranular path and the consequent interface bridging process can be partitioned More >

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