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  • Open AccessOpen Access

    ARTICLE

    An Improved Wheeler Residual Stress Model For Remaining Life Assessment of Cracked Plate Panels

    A. Rama Chandra Murthy1, G.S. Palani1, Nagesh R. Iyer1
    CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 289-300, 2004, DOI:10.3970/cmc.2004.001.289
    Abstract In this paper an improved Wheeler residual stress model has been proposed for remaining life assessment of cracked plate panels under variable amplitude loading (VAL). The improvement to the Wheeler residual stress model is in terms of the expressions for the shaping exponent, which is generally obtained through experiments. Simple expressions for the computation of shaping exponent have been proposed for compact tension (CT) specimen and plate panels with a center crack or an edge crack. The remaining life assessment has been carried out by employing linear elastic fracture mechanics (LEFM) principles. In the present study, the degree of influence… More >

  • Open AccessOpen Access

    ARTICLE

    Active Control of Laminar Boundary Layer Using Various Wall Motions

    J. Qiu1, T. Hayase1, T. Okutani1
    CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 301-308, 2004, DOI:10.3970/cmc.2004.001.301
    Abstract In this study, three types of surface motion of wall motion actuators were proposed and used to control the Tollmien-Schlichting (T-S) wave in the laminar boundary layer of a plate. These three types of motion are standing transverse wave (with out-of-plane displacement), traveling transverse wave (with out-of-plane displacement) and standing longitudinal wave (with in-plane displacement). The length of a wall motion actuator was set to 1, 2 or 3 cycles of waveform. Numerical simulation was performed on the generation of T-S wave and its suppression with the three types of surface motion of the wall motion actuator and the dependence… More >

  • Open AccessOpen Access

    ARTICLE

    Plasma Etching to Enhance Visibility of Nano Particles in Nanocomposites

    Kunigal N.Shivakumar1, Shivalingappa Lingaiah2, Robert Sadler2, Matthew Sharpe2
    CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 309-318, 2004, DOI:10.3970/cmc.2004.001.309
    Abstract The exfoliation and dispersion of nanoclay (2% by weight) and nanovermiculite (2% by weight) particles in a polymer matrix is analyzed using the Scanning Electron Microscope (SEM) after a low temperature air plasma etch. The plasma etch preferentially removes the polymer to expose the nanoparticles. Both Argon and air have been used as the etching media to study the etching process. SEM analysis illustrate the results of the etching in flat and edge surfaces of both nanoclay (MMT) and nanovermiculite (VMT) filled polymer. Both the MMT and VMT were dispersed using a IKA high shear mixer and a Sonicator. More >

  • Open AccessOpen Access

    ARTICLE

    Green's First Identity Method for Boundary-Only Solution of Self-Weight in BEM Formulation for Thick Slabs

    Youssef F. Rashed1
    CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 319-326, 2004, DOI:10.3970/cmc.2004.001.319
    Abstract The present paper develops a new technique for treatment of self-weight for building slabs in the boundary element method (BEM). Due to the use of BEM in the analysis, all defined variables are presented on the slab boundary (mesh is defined only along the slab boundary). Self-weight, however, is usually defined over slab domain, hence domain discretisation is required, which spoils the main advantage of the BEM. In this paper a new method is presented to transform self-weight domain integrals to the boundary for such slabs. The proposed method is based on using the so-called Green's first identity. All new… More >

  • Open AccessOpen Access

    ARTICLE

    Lamb Wave Interaction with Delaminations in CFRP Laminates

    Jiayong Tian1,2, Ulrich Gabbert2, Harald Berger2, Xianyue Su1
    CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 327-336, 2004, DOI:10.3970/cmc.2004.001.327
    Abstract In this paper, we investigate Lamb wave interaction with delamination in an infinite carbon fiber reinforced plastics (CFRP) laminate by a hybrid method. The infinite CFRP laminate is divided into an exterior zone and an interior zone. In the exterior zone, the wave fields are expressed by wave mode expansion. In the interior zone, the wave fields are modeled by the finite element method (FEM). Considering the continuity condition at the boundary between the exterior and interior zones, the global wave fields can be calculated. Lastly, numerical examples show how a delamination in the laminate influences the mode conversion of… More >

  • Open AccessOpen Access

    ARTICLE

    A Refined Asymptotic Theory for the Nonlinear Analysis of Laminated Cylindrical Shells

    Chih-Ping Wu1, Yen-Wei Chi1
    CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 337-352, 2004, DOI:10.3970/cmc.2004.001.337
    Abstract Within the framework of the three-dimensional (3D) nonlinear elasticity, a refined asymptotic theory is developed for the nonlinear analysis of laminated circular cylindrical shells. In the present formulation, the basic equations including the nonlinear relations between the finite strains (Green strains) and displacements, the nonlinear equilibrium equations in terms of the Kirchhoff stress components and the generalized Hooke's law for a monoclinic elastic material are considered. After using proper nondimensionalization, asymptotic expansion, successive integration and then bringing the effects of transverse shear deformation into the leading-order level, we obtain recursive sets of the governing equations for various orders. It is… More >

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