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  • Open Access

    ARTICLE

    Reliability Analysis for Complex Systems based on Dynamic Evidential Network Considering Epistemic Uncertainty

    Rongxing Duan1, Yanni Lin1, Longfei Hu1

    CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.1, pp. 17-34, 2017, DOI:10.3970/cmes.2017.113.015

    Abstract Fault tolerant technology has greatly improved the reliability of modern systems on one hand and makes their failure mechanisms more complex on the other. The characteristics of dynamics of failure, diversity of distribution and epistemic uncertainty always exist in these systems, which increase the challenges in the reliability assessment of these systems significantly. This paper presents a novel reliability analysis framework for complex systems within which the failure rates of components are expressed in interval numbers. Specifically, it uses a dynamic fault tree (DFT) to model the dynamic fault behaviors and copes with the epistemic More >

  • Open Access

    ARTICLE

    Optimization of Nonlinear Vibration Characteristics for Seismic Isolation Rubber

    A. Takahashi1, T. Shibata2, K. Motoyama3, K. Misaji4

    CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.1, pp. 1-15, 2017, DOI:10.3970/cmes.2017.113.001

    Abstract A method for reducing the damage to a structure caused by an earthquake namely, using laminated rubber for seismic isolation is proposed, and the vibration characteristics of the rubber (which minimizes the seismic response of the structure during an earthquake) is optimized. A method called “Equivalent Linear System using Restoring Force Model of Power Function Type” (PFT-ELS) is applied to nonlinear vibration analysis of the rubber. In that analysis, a building with 15 layers of the laminated rubber is modeled. The seismic response of the building is analyzed, and the usefulness of the laminated rubber More >

  • Open Access

    ARTICLE

    Applying a Step Approach Method in Solving the Multi-Frequency Radiation From a Complex Obstacle

    Jui-Hsiang Kao1

    CMES-Computer Modeling in Engineering & Sciences, Vol.112, No.1, pp. 59-73, 2016, DOI:10.3970/cmes.2016.112.059

    Abstract In this paper, a step approach method in the time domain is developed to calculate the radiated waves from an arbitrary obstacle pulsating with multiple frequencies. The computing scheme is based on the Boundary Integral Equation and derived in the time domain; thus, the time-harmonic Neumann boundary condition can be imposed. By the present method, the values of the initial conditions are set to zero, and the approach process is carried forward in a loop from the first time step to the last. At each time step, the radiated pressure on each element is updated. More >

  • Open Access

    ARTICLE

    A Finite Element Procedure for Analysis of Chemo-Mechanical Coupling Behavior of Hydrogels

    Wei Wei1,2, Qingsheng Yang1,3

    CMES-Computer Modeling in Engineering & Sciences, Vol.112, No.1, pp. 33-58, 2016, DOI:10.3970/cmes.2016.112.033

    Abstract Chemo-mechanical coupling behavior of materials is a transformation process between mechanical and chemical energy. In this paper, based on the coupled chemo-mechanical constitutive equations and governing equations during isothermal process, the equivalent integral forms of chemo-mechanical coupling governing equations and corresponding finite element procedure are obtained by using Hamilton's principle. An isoparametric plane element for chemo-mechanical coupling is associated into ABAQUS finite element package through user element subroutine UEL. The numerical examples exhibit that the ionic concentration variation can cause mechanical deformation and mechanical action can produce redistribution of ionic concentration for hydrogels. It is More >

  • Open Access

    ARTICLE

    Are “Higher-Order” and “Layer-wise Zig-Zag” Plate & Shell Theories Necessary for Functionally Graded Materials and Structures?

    Yaping Zhang1, Qifeng Fan2, Leiting Dong2,3, Satya N. Atluri4

    CMES-Computer Modeling in Engineering & Sciences, Vol.112, No.1, pp. 1-32, 2016, DOI:10.3970/cmes.2016.112.001

    Abstract Similar to the very vast prior literature on analyzing laminated composite structures, "higher-order" and "layer-wise higher-order" plate and shell theories for functionally-graded (FG) materials and structures are also widely popularized in the literature of the past two decades. However, such higher-order theories involve (1) postulating very complex assumptions for plate/shell kinematics in the thickness direction, (2) defining generalized variables of displacements, strains, and stresses, and (3) developing very complex governing equilibrium, compatibility, and constitutive equations in terms of newly-defined generalized kinematic and generalized kinetic variables. Their industrial applications are thus hindered by their inherent complexity,… More >

  • Open Access

    ARTICLE

    A Unification of the Concepts of the Variational Iteration, Adomian Decomposition and Picard Iteration Methods; and a Local Variational Iteration Method

    Xuechuan Wang1, Satya N. Atluri2

    CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.6, pp. 567-585, 2016, DOI:10.3970/cmes.2016.111.567

    Abstract This paper compares the variational iteration method (VIM), the Adomian decomposition method (ADM) and the Picard iteration method (PIM) for solving a system of first order nonlinear ordinary differential equations (ODEs). A unification of the concepts underlying these three methods is attempted by considering a very general iterative algorithm for VIM. It is found that all the three methods can be regarded as special cases of using a very general matrix of Lagrange multipliers in the iterative algorithm of VIM. The global variational iteration method is briefly reviewed, and further recast into a Local VIM, More >

  • Open Access

    ARTICLE

    Permissible Wind Conditions for Optimal Dynamic Soaring with a Small Unmanned Aerial Vehicle

    Liu Duo-Neng1,2, Hou Zhong-Xi1, Guo Zheng1, Yang Xi-Xiang1, Gao Xian-Zhong1

    CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.6, pp. 531-565, 2016, DOI:10.3970/cmes.2016.111.531

    Abstract Dynamic soaring is a flight maneuver to exploit gradient wind field to extend endurance and traveling distance. Optimal trajectories for permissible wind conditions are generated for loitering dynamic soaring as well as for traveling patterns with a small unmanned aerial vehicle. The efficient direct collection approach based on the Runge-Kutta integrator is used to solve the optimization problem. The fast convergence of the optimization process leads to the potential for real-time applications. Based on the results of trajectory optimizations, the general permissible wind conditions which involve the allowable power law exponents and feasible reference wind… More >

  • Open Access

    ARTICLE

    Atomic Exponential Basis Function Eup(x,ω) - Development and Application

    Nives Brajčić Kurbaša1, Blaž Gotovac1, Vedrana Kozulić1

    CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.6, pp. 493-530, 2016, DOI:10.3970/cmes.2016.111.493

    Abstract This paper presents exponential Atomic Basis Functions (ABF), which are called Eup(x,ω). These functions are infinitely differentiable finite functions that unlike algebraic up(x) basis functions, have an unspecified parameter - frequency w. Numerical experiments show that this class of atomic functions has good approximation properties, especially in the case of large gradients (Gibbs phenomenon). In this work, for the first time, the properties of exponential ABF are thoroughly investigated and the expression for calculating the value of the basis function at an arbitrary point of the domain is given in a form suitable for implementation in More >

  • Open Access

    ARTICLE

    18-DOF Triangular Quasi-Conforming Element for Couple Stress Theory

    Xiangkui Zhang1, Changsheng Wang1,2, Ping Hu1

    CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.6, pp. 473-492, 2016, DOI:10.3970/cmes.2016.111.473

    Abstract The basic idea of quasi-conforming method is that the strain-dis- placement equations are weakened as well as the equilibrium equations. In this paper, an 18-DOF triangular element for couple stress theory is proposed within the framework of quasi-conforming technique. The formulation starts from truncated Taylor expansion of strains and appropriate interpolation functions are chosen to calculate strain integration. This element satisfies C0 continuity with second order accuracy and weak C1 continuity simultaneously. Numerical examples demonstrate that the proposed model can pass the C0 More >

  • Open Access

    ARTICLE

    Simple Efficient Smart Finite Elements for the Analysis of Smart Composite Beams

    M. C. Ray1, L. Dong2, S. N. Atluri3

    CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.5, pp. 437-471, 2016, DOI:10.3970/cmes.2016.111.437

    Abstract This paper is concerned with the development of new simple 4-noded locking-alleviated smart finite elements for modeling the smart composite beams. The exact solutions for the static responses of the overall smart composite beams are also derived for authenticating the new smart finite elements. The overall smart composite beam is composed of a laminated substrate conventional composite beam, and a piezoelectric layer attached at the top surface of the substrate beam. The piezoelectric layer acts as the actuator layer of the smart beam. Alternate finite element models of the beams, based on an "equivalent single… More >

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