Susan Thomas¹, Dr. Balamati Choudhury²

CMC-Computers, Materials & Continua, Vol.52, No.3, pp. 133-141, 2016, DOI:10.3970/cmc.2016.052.132

Abstract A novel microwave cloak using circular split ring resonator (SRR) based metamaterial structure has been proposed in this paper. The cloak which operates at a frequency of 10.6 GHz is composed of cylindrical dielectric sheets printed with circular split ring resonators of spatially varying and anisotropic material properties. The article also focuses on the phenomenon of resonant splitting in circular SRR microwave cloak. A detailed analysis of various linear metamaterial arrays and their response has also been elucidated. More >

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 >

Wei Wei^1,2, Qingsheng Yang^1,3

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 >

Yaping Zhang¹, Qifeng Fan², Leiting Dong^2,3, 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 >

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 >

Liu Duo-Neng^1,2, 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 - 01 March 2022

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 >

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 >

Xiangkui Zhang¹, Changsheng Wang^1,2, 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 >

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 >

Chein-Shan Liu^1,2,3, Wen Chen¹, Ji Lin¹

CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.5, pp. 421-435, 2016, DOI:10.3970/cmes.2016.111.421

Abstract In order to recover unknown space-dependent function G(x) or unknown time-dependent function H(t) in the wave source F(x; t) = G(x)H(t), we develop a technique of homogenized function and differencing equations, which can significantly reduce the difficulty in the inverse wave source recovery problem, only needing to solve a few equations in the problem domain, since the initial condition/ boundary conditions and a supplementary final time condition are satisfied automatically. As a consequence, the eigenfunctions are used to expand the trial solutions, and then a small scale linear system is solved to determine the expansion More >