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  • Open Access


    An Efficient Reliability-based Optimization Method for Uncertain Structures Based on Non-probability Interval Model

    C. Jiang1, Y.C. Bai1, X. Han1,2, H.M. Ning1

    CMC-Computers, Materials & Continua, Vol.18, No.1, pp. 21-42, 2010, DOI:10.3970/cmc.2010.018.021

    Abstract In this paper, an efficient interval optimization method based on a reliability-based possibility degree of interval (RPDI) is suggested for the design of uncertain structures. A general nonlinear interval optimization problem is studied in which the objective function and constraints are both nonlinear and uncertain. Through an interval order relation and a reliability-based possibility degree of interval, the uncertain optimization problem is transformed into a deterministic one. A sequence of approximate optimization problems are constructed based on the linear approximation technique. Each approximate optimization problem can be changed to a traditional linear programming problem, which More >

  • Open Access


    A Lie-Group Adaptive Method for Imaging a Space-Dependent Rigidity Coefficient in an Inverse Scattering Problem of Wave Propagation

    Chein-Shan Liu1

    CMC-Computers, Materials & Continua, Vol.18, No.1, pp. 1-20, 2010, DOI:10.3970/cmc.2010.018.001

    Abstract We are concerned with the reconstruction of an unknown space-dependent rigidity coefficient in a wave equation. This problem is known as one of the inverse scattering problems. Based on a two-point Lie-group equation we develop a Lie-group adaptive method (LGAM) to solve this inverse scattering problem through iterations, which possesses a special character that by using onlytwo boundary conditions and two initial conditions, as those used in the direct problem, we can effectively reconstruct the unknown rigidity function by aself-adaption between the local in time differential governing equation and the global in time algebraic Lie-group More >

  • Open Access


    On Solving the Direct/Inverse Cauchy Problems of Laplace Equation in a Multiply Connected Domain, Using the Generalized Multiple-Source-Point Boundary-Collocation Trefftz Method &Characteristic Lengths

    Weichung Yeih1, Chein-Shan Liu2, Chung-Lun Kuo3, Satya N. Atluri4

    CMC-Computers, Materials & Continua, Vol.17, No.3, pp. 275-302, 2010, DOI:10.3970/cmc.2010.017.275

    Abstract In this paper, a multiple-source-point boundary-collocation Trefftz method, with characteristic lengths being introduced in the basis functions, is proposed to solve the direct, as well as inverse Cauchy problems of the Laplace equation for a multiply connected domain. When a multiply connected domain with genus p (p>1) is considered, the conventional Trefftz method (T-Trefftz method) will fail since it allows only one source point, but the representation of solution using only one source point is impossible. We propose to relax this constraint by allowing many source points in the formulation. To set up a complete… More >

  • Open Access


    Stable Boundary and Internal Data Reconstruction in Two-Dimensional Anisotropic Heat Conduction Cauchy Problems Using Relaxation Procedures for an Iterative MFS Algorithm

    Liviu Marin1

    CMC-Computers, Materials & Continua, Vol.17, No.3, pp. 233-274, 2010, DOI:10.3970/cmc.2010.017.233

    Abstract We investigate two algorithms involving the relaxation of either the given boundary temperatures (Dirichlet data) or the prescribed normal heat fluxes (Neumann data) on the over-specified boundary in the case of the iterative algorithm of Kozlov91 applied to Cauchy problems for two-dimensional steady-state anisotropic heat conduction (the Laplace-Beltrami equation). The two mixed, well-posed and direct problems corresponding to every iteration of the numerical procedure are solved using the method of fundamental solutions (MFS), in conjunction with the Tikhonov regularization method. For each direct problem considered, the optimal value of the regularization parameter is chosen according More >

  • Open Access


    Nanostiffening in Polymeric Nanocomposites

    J. Wang1, D. C. C. Lam2

    CMC-Computers, Materials & Continua, Vol.17, No.3, pp. 215-232, 2010, DOI:10.3970/cmc.2010.017.215

    Abstract Selected elastic moduli of nanocomposites are higher than the elastic moduli of microcomposites. Molecular immobilization and crystallization at the interfaces had been proposed as potential causes, but studies suggested that these effects are minor and cannot be used to explain the magnitude observed in nanocomposites with >3nm particles. Alternately, molecular simulation of polymer deformation showed that rotation gradients can lead to additional molecular rotations and stiffen the matrix. The stiffening is characterized by the nanostiffening material parameter, l2. In this investigation, an analytical expression for nanostiffening in nanocomposites was developed using finite element analysis. The More >

  • Open Access


    In-plane Crushing Analysis of Cellular Materials Using Vector Form Intrinsic Finite Element

    T.Y. Wu1, W.C. Tsai2, J.J. Lee2

    CMC-Computers, Materials & Continua, Vol.17, No.3, pp. 175-214, 2010, DOI:10.3970/cmc.2010.017.175

    Abstract The crushing of cellular materials is a highly nonlinear problem, for which geometrical, material, and contact/impact must be treated in one analysis. In order to develop a framework able to solve it efficiently and accurately, in this paper procedures for in-plane crushing analysis of cellular materials using vector form intrinsic finite element (VFIFE) is performed. A beam element of VFIFE is employed to handle large rotation and large deflection in the cell walls. An elastic-plastic material model with mixed hardening rule is adopted to account for material nonlinearity. In addition, an efficient contact/impact algorithm is More >

  • Open Access


    A Novel Framework for Building Materials Knowledge Systems

    Surya R. Kalidindi1,2,3, Stephen R. Niezgoda1, Giacomo L,i1,1, Tony Fast1

    CMC-Computers, Materials & Continua, Vol.17, No.2, pp. 103-126, 2010, DOI:10.3970/cmc.2010.017.103

    Abstract This paper presents a novel mathematical framework for building a comprehensive materials knowledge system (MKS) to extract, store and recall hierarchical structure-property-processing linkages for a broad range of material systems. This new framework relies heavily on the use of computationally efficient FFT (Fast Fourier Transforms)-based algorithms for data-mining local structure-response-structure evolution linkages from large numerical datasets produced by established modelling strategies for microscale phenomena. Another salient feature of this new framework is that it facilitates flow of high fidelity information in both directions between the constituent length scales, and thereby offers a new strategy for More >

  • Open Access


    The Effect of the Geometrical Non-Linearity on the Stress Distribution in the Infinite Elastic Body with a Periodically Curved Row of Fibers

    Surkay D. Akbarov1,2, Resat Kosker3, Yasemen Ucan3

    CMC-Computers, Materials & Continua, Vol.17, No.2, pp. 77-102, 2010, DOI:10.3970/cmc.2010.017.077

    Abstract In the framework of the piecewise homogeneous body model with the use of the three-dimensional geometrically non-linear exact equations of the theory of elasticity, the method for determination of the stress-strain state in the infinite body containing periodically located row of periodically curved fibers is developed. It is assumed that the midlines of the fibers are in the same plane. With respect to the location of the fibers according to each other the sinphase and antiphase curving cases are considered. Numerical results on the effect of the geometrical non-linearity to the values of the self More >

  • Open Access


    Effects of Surface Orientation and Temperature on Tensile Deformation of Gold Nanowires

    Qunfeng Liu1, gping Shen2

    CMC-Computers, Materials & Continua, Vol.17, No.1, pp. 59-76, 2010, DOI:10.3970/cmc.2010.017.059

    Abstract Molecular Dynamics (MD) simulations have been performed using the EAM potential to investigate the deformation behaviors and mechanical properties of <100>/{100} gold nanowires with square cross-section at a certain strain rate under different temperatures ranging from 10 K to 700 K. It is found that <100>/{100} gold nanowires at high temperatures tend to form the extended stable nanobridges-Helical Multi-shell Structure (HMS), which is similar to the deformation behavior of <110> gold nanowires at room temperature reported in the previous experimental observations and simulations. The effect of temperature on the mechanical properties and deformation behaviors of gold nanowires… More >

  • Open Access


    Effects of TGO Roughness on Indentation Response of Thermal Barrier Coatings

    Taotao Hu1, gping Shen1,2

    CMC-Computers, Materials & Continua, Vol.17, No.1, pp. 41-58, 2010, DOI:10.3970/cmc.2010.017.041

    Abstract In this paper, an axisymmetric indentation model is set up to calculate the effects of the roughness of the thermally grown oxide (TGO) layer, which was modeled as a sinusoidal wave, on the indentation response of the thermal barrier coatings. It is found that the amplitude, wavelength, and thickness of the thermally grown oxide layer have obvious influences on the indentation response, while the effect of the indenter position can be neglected. In the top coating layer, residual stress mainly occurs below the indenter and around the nearest two peaks of the thermally grown oxide More >

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