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  • 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 - 22 December 2020

    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

    Image Processing/Machine-Learning for Auto-Labeling of Steel Images on Present Microstructures

    Dmitry S. Bulgarevich1,*, Susumu Tsukamoto1, Tadashi Kasuya2, Masahiko Demura1, Makoto Watanabe1,3

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 122-122, 2019, DOI:10.32604/icces.2019.05271

    Abstract The microstructure of steel greatly determines its mechanical properties/performance and holds information on chemical composition and processing history. Therefore, quantitative analysis of optical or SEM images on formed microstructure phases is one of the primary interests for metallurgy. So far, such analyses in laboratories are done manually by experts and are very time consuming. However, with modern microscopy techniques of automated image acquisitions over the large imaging areas and even by using of sample slicing for three-dimensional imaging, the amount of image data could be overwhelming for manual examinations. In this respect, there is a… More >

  • Open Access

    ARTICLE

    From Ordered to Disordered: The Effect of Microstructure on Composite Mechanical Performance

    L.B. Borkowski1, K.C. Liu1, A. Chattopadhyay1

    CMC-Computers, Materials & Continua, Vol.37, No.3, pp. 161-193, 2013, DOI:10.3970/cmc.2013.037.161

    Abstract The microstructural variation in fiber-reinforced composites has a direct relationship with its local and global mechanical performance. When micromechanical modeling techniques for unidirectional composites assume a uniform and periodic arrangement of fibers, the bounds and validity of this assumption must be quantified. The goal of this research is to quantify the influence of microstructural randomness on effective homogeneous response and local inelastic behavior. The results indicate that microstructural progression from ordered to disordered decreases the tensile modulus by 5%, increases the shear modulus by 10%, and substantially increases the magnitude of local inelastic fields. The More >

  • Open Access

    ARTICLE

    Stochastic Macro Material Properties, Through Direct Stochastic Modeling of Heterogeneous Microstructures with Randomness of Constituent Properties and Topologies, by Using Trefftz Computational Grains (TCG)

    Leiting Dong1,2, Salah H. Gamal3, Satya N. Atluri2,4

    CMC-Computers, Materials & Continua, Vol.37, No.1, pp. 1-21, 2013, DOI:10.3970/cmc.2013.037.001

    Abstract In this paper, a simple and reliable procedure of stochastic computation is combined with the highly accurate and efficient Trefftz Computational Grains (TCG), for a direct numerical simulation (DNS) of heterogeneous materials with microscopic randomness. Material properties of each material phase, and geometrical properties such as particles sizes and distribution, are considered to be stochastic with either a uniform or normal probabilistic distributions. The objective here is to determine how this microscopic randomness propagates to the macroscopic scale, and affects the stochastic characteristics of macroscopic material properties. Four steps are included in this procedure: (1)… More >

  • Open Access

    ARTICLE

    Modeling of Random Bimodal Structures of Composites (Application to Solid Propellants): II. Estimation of Effective Elastic Moduli

    V.A. Buryachenko1,2

    CMES-Computer Modeling in Engineering & Sciences, Vol.85, No.5, pp. 417-446, 2012, DOI:10.3970/cmes.2012.085.417

    Abstract We consider a linearly elastic composite medium, which consists of a homogeneous matrix containing a statistically homogeneous set of multimodal spherical inclusions modeling the morphology of heterogeneous solid propellants (HSP). Estimates of effective elastic moduli are performed using the multiparticle effective field method (MEFM) directly taking into account the interaction of different inclusions. Because of this, the effective elastic moduli of the HSP evaluated by the MEFM are sensitive to both the relative size of the inclusions (i.e., their multimodal nature) and the radial distribution functions (RDFs) estimated from experimental data, as well as from More >

  • Open Access

    ARTICLE

    Modeling of Random Bimodal Structures of Composites (Application to Solid Propellants): I. Simulation of Random Packs

    V.A. Buryachenko1,2, T.L. Jackson2,3, G. Amadio3

    CMES-Computer Modeling in Engineering & Sciences, Vol.85, No.5, pp. 379-416, 2012, DOI:10.3970/cmes.2012.085.379

    Abstract We consider a composite medium, which consists of a homogeneous matrix containing a statistically homogeneous set of multimodal spherical inclusions. This model is used to represent the morphology of heterogeneous solid propellants (HSP) that are widely used in the rocket industry. The Lubachevsky-Stillinger algorithm is used to generate morphological models of HSP with large polydisperse packs of spherical inclusions. We modify the algorithm by proposing a random shaking procedure that leads to the stabilization of a statistical distribution of the simulated structure that is homogeneous, highly mixed, and protocol independent (in sense that the statistical 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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