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  • Open Access

    ARTICLE

    Nonlinear Dynamic Analysis of Three-Dimensional Elasto-Plastic Solids by the Meshless Local Petrov-Galerkin (MLPG) Method

    A. Rezaei Mojdehi1,2, A. Darvizeh3, A. Basti2

    CMC-Computers, Materials & Continua, Vol.29, No.1, pp. 15-40, 2012, DOI:10.3970/cmc.2012.029.015

    Abstract The meshless local Petrov-Galerkin approach is proposed for the nonlinear dynamic analysis of three-dimensional (3D) elasto-plastic problems. Galerkin weak-form formulation is applied to derive the discrete governing equations. A weak formulation for the set of governing equations is transformed into local integral equations on local sub-domains by using a unit test function and local weak-form formulation in three dimensional continua for the general dynamic problems is derived. Three dimensional Moving Least-Square (MLS) approximation is considered as shape function to approximate the field variable of scattered nodes in the problem domain. Normality hypothesis of plasticity is adopted to define the stress-strain… More >

  • Open Access

    ARTICLE

    Transient Wear Simulation in Sliding Contacts of Spur Gear Teeth

    Y.J. Chen1, N. Huber1,2

    CMC-Computers, Materials & Continua, Vol.29, No.1, pp. 1-14, 2012, DOI:10.3970/cmc.2012.029.001

    Abstract Gear transmission is important in engineering due to its high efficiency in transferring both power and motion. As a surface phenomenon, wear may change the gear geometry, cause a non-uniform gear rate and increase dynamic effects, all of which can lead to reduced efficiency and even severe tooth failure. In numerical predictions of wear, the conventional method, where the contact pressure over the slip distance is integrated, will cause a computation bottle-neck. To obtain an accurate integration of the wear within the small, fast moving contact area, the finite element model needs to be meshed very finely, and the time… More >

  • Open Access

    ARTICLE

    A Local Adaptive Differential Quadrature Method for Multi-Dimensional Inverse Scattering Problem of Wave Propagation

    Jiun-Yu Wu1,2, Hui-Ching Wang1, Ming-I Char1, Bo-Chen Tai1

    CMC-Computers, Materials & Continua, Vol.28, No.3, pp. 261-280, 2012, DOI:10.3970/cmc.2012.028.261

    Abstract In this paper, we use the Local adaptive differential quadrature method (La-DQM) to solve multi-dimensional inverse scattering problem (ISP) of wave propagation. The La-DQM uses fictitious points to tackle the high-order differential equations with multi-boundary conditions and numerical results can be obtain directly in the calculation process. Six examples show the effectiveness and accuracy of the La-DQM in providing excellent estimates of unknown wave propagation from the given data. We think that the scheme is applicable to the ISP of wave propagation. Numerical results show that the La-DQM is powerful method for solving the inverse scattering problem of wave propagation. More >

  • Open Access

    ARTICLE

    A Multiple-Precision Study on the Modified Collocation Trefftz Method

    Chia-Cheng Tsai1, Po-Ho Lin2

    CMC-Computers, Materials & Continua, Vol.28, No.3, pp. 231-260, 2012, DOI:10.3970/cmc.2012.028.231

    Abstract Recently, Liu (CMES 21(2007), 53) developed the modified collocation Trefftz method (MCTM) by setting a characteristic length slightly larger than the maximum radius of the computational domain. In this study, we find that the range of admissible characteristic length can be significantly enlarged if the LU decomposition is applied for solving the resulted dense unsymmetric matrix. Furthermore, we discover a range formula for admissible characteristic length, in which the number of the T-complete functions, the shape of the computation domain, and the exponent bits of the involved floating-point arithmetic have been taken into consideration. In order to validate the prescribed… More >

  • Open Access

    ARTICLE

    Statistical Analysis of Macromolecular Chains in the Space Filled by Nanoparticles

    J. Zidek1,2, J. Kucera1, J. Jancar1,2

    CMC-Computers, Materials & Continua, Vol.28, No.3, pp. 213-230, 2012, DOI:10.3970/cmc.2012.028.213

    Abstract The paper presents a combination of worm-like chain numerical models and one with a finite set of nano-particles. The primary objective of the models was to analyze the distribution of space in a system filled by particles. Information on the distribution of space was compared to properties of chains inside the set of particles. The set of nanoparticles was constructed with a tool generating a finite set of particles that is randomly distributed in a given space. The particles have a prescribed volume fraction and uniform size. First, the proportions of chains and particles were compared. The length of chain… More >

  • Open Access

    ARTICLE

    Maximization of Fundamental Frequencies of Axially Compressed Laminated Curved Panels against Fiber Orientation

    Hsuan-Teh Hu1, Jun-Ming Chen2

    CMC-Computers, Materials & Continua, Vol.28, No.3, pp. 181-212, 2012, DOI:10.3970/cmc.2012.028.181

    Abstract Free vibration analyses of laminated curved panels subjected to axial compressive forces are carried out by employing the Abaqus finite element program. The fundamental frequencies of these composite laminated curved panels with a given material system are then maximized with respect to fiber orientations by using the golden section method. Through a parametric study, the significant influences of the end conditions, the panel aspect ratio, the panel curvature and the compressive force on the maximum fundamental frequencies and the associated optimal fiber orientations are demonstrated and discussed. More >

  • Open Access

    ARTICLE

    Chemical Stresses Induced by Boundary Layer Diffusion in a Cylindrical Sandwich Composite

    Sun-Chien Ko1,2, Chen-Ti Hu1, Sanboh Lee1, Y.T. Chou3

    CMC-Computers, Materials & Continua, Vol.28, No.2, pp. 165-180, 2012, DOI:10.3970/cmc.2012.028.165

    Abstract The chemical stresses developed in a cylindrical sandwich composite during radial boundary layer diffusion have been investigated. The system consists of a thin layer A of circular cross section sandwiched between two semi-infinite outer layers B, with the diffusivity of diffusant in A (DA) being much greater than that in B (DB). Two boundary conditions, the constant surface concentration and the instantaneous surface concentration, were considered. The concentration distributions were obtained by the Bessel-Laplace transform method. The stress functions were solved analytically based on the linear elasticity. Numerical computations were performed to illustrate the effects of the diffusivity ratio (DA/DB)… More >

  • Open Access

    ARTICLE

    3D Analysis of the Forced Vibration of a Prestressed Rectangular Composite Plate With Two Neighboring Cylindrical Cavities

    S.D. Akbarov1,2, N. Yahnioglu3, U. Babuscu Yesil3

    CMC-Computers, Materials & Continua, Vol.28, No.2, pp. 147-164, 2012, DOI:10.3970/cmc.2012.028.147

    Abstract This paper presents an analysis of the forced vibration of an initially stressed rectangular composite plate containing two neighboring cylindrical cavities. The initial stresses are caused by stretching or compressing of the plate with uniformly distributed normal static forces acting on the two opposite end-planes which are parallel to the central axes of the aforementioned cylindrical cavities. The influence of the initial stresses on the stress concentration around the cavities caused by the additional uniformly distributed time harmonic forces acting on the upper face plane of the plate are given. The considered problem is formulated within the framework of the… More >

  • Open Access

    ARTICLE

    A Robust Inverse Method Based on Least Square Support Vector Regression for Johnson-cook Material Parameters

    Hu Wang1, Weiyi Li1, Guangyao Li1

    CMC-Computers, Materials & Continua, Vol.28, No.2, pp. 121-146, 2012, DOI:10.3970/cmc.2012.028.121

    Abstract The purpose of this study is to propose a robust inverse method for estimating Johnson-Cook material parameters. The method is shown through illustrative examples for two different advanced high strength steel (AHSS) materials (DP980 and TRIP780) using set of data from impact experiments with different velocities. Compared with widely mixed numerical experimental methods, the suggested inverse method has the capability to guarantee the robustness of the obtained parameters by considering uncertainties. The inverse problem is converted into multi-objective optimization problems. Furthermore, in order to improve the performance in efficiency and accuracy, metamodeling techniques and global optimization method are integrated. The… More >

  • Open Access

    ARTICLE

    Eigenvalue Analysis of MEMS Components with Multi-defect using Infinite Element Method Algorithm

    De-Shin Liu1,2, Chin-Yi Tu1, Cho-Liang Chung3

    CMC-Computers, Materials & Continua, Vol.28, No.2, pp. 97-120, 2012, DOI:10.3970/cmc.2012.028.097

    Abstract Manufacturing defects in the membrane of MEMS (Micro-Electro-Mechanical-Systems) structures have a significant effect on the sensitivity and working range of the device. Thus, in optimizing the design of MEMS devices, it is essential that the effects of membrane defects (e.g., cracks) can be predicted in advance. Accordingly, this study proposes the detailed two-dimensional Infinite Element Method (IEM) formulation with Infinite Element (IE)-Finite Element (FE) coupling scheme for analyzing the out-of-plane vibration of isotropic MEMS membranes containing one or more tip cracks. In the proposed approach, a degenerative computation scheme is used to condense the multiple element layers of the IEM… More >

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