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Search Results (9)
  • Open Access


    Numerical Aspects of Isogeometric Boundary Element Methods: (Nearly) Singular Quadrature, Trimmed NURBS and Surface Crack Modeling

    Xuan Peng1,*, Haojie Lian2,*

    CMES-Computer Modeling in Engineering & Sciences, Vol.130, No.1, pp. 513-542, 2022, DOI:10.32604/cmes.2022.017410

    Abstract This work presents some numerical aspects of isogeometric boundary element methods (IGABEM). The behavior of hyper-singular and nearly-singular integration is first explored on the distorted NURBS surface. Several numerical treatments are proposed to enhance the quadrature in the framework of isogeometric analysis. Then a numerical implementation of IGABEM on the trimmed NURBS is detailed. Based on this idea, the surface crack problem is modeled incorporation with the phantom element method. The proposed method allows the crack to intersect with the boundary of the body while preserving the original parametrization of the NURBS-based CAD geometry. More >

  • Open Access


    Closure Effect Evaluation of Surface Crack Growth under Cyclic Bending using S-FEM

    Masanori Kikuchi1, Kazuhiro Suga1

    Structural Durability & Health Monitoring, Vol.6, No.3&4, pp. 289-304, 2010, DOI:10.3970/sdhm.2010.006.289

    Abstract Crack closure effect on interaction of two surface crack growth processes by fatigue is studied. At first, change of C value in Paris' law along crack front of single surface crack is measured experimentally. It is shown that C value decreases near specimen surface. Crack closure effect is studied numerically for a surface crack by elastic-plastic cyclic analyses. It is found that closure effect appears more strongly near specimen surface than the maximum-depth point. By determining effective stress intensity factor including closure effect, it is shown that change of C value is equal to the change of closure effect along… More >

  • Open Access


    An Automated Procedure for the Geometrical Modelling of a Surface Crack Front

    J. Toribio1, J.C. Matos2, B. González1, J. Escuadra2

    Structural Durability & Health Monitoring, Vol.5, No.1, pp. 57-72, 2009, DOI:10.3970/sdhm.2009.005.057

    Abstract In this paper an automatic (analytical-numerical) procedure is proposed to model the front of a transverse surface crack located in the circular section of a lineal structural element (wire, cable, strand, rod, shaft,..., i.e., a cylindrical geometry) by means of a fitting ellipse, obtaining the ellipse parameters from a series of points in therealcrack front and adjusting them to thetheoreticalfitting ellipse by a least square method. For symmetric cracks two modelling procedures are formulated: (i) in the first one, a fitting ellipse is used wit its centre belonging to the periphery of the circular section of the cylinder; (ii) in… More >

  • Open Access


    Applications of DTALE: Damage Tolerance Analysis and Life Enhancement [3-D Non-plannar Fatigue Crack Growth]

    S. N. Atluri1

    Structural Durability & Health Monitoring, Vol.1, No.1, pp. 1-20, 2005, DOI:10.3970/sdhm.2005.001.001

    Abstract The solution of three-dimensional cracks (arbitrary surfaces of discontinuity) in solids and structures is considered. The BEM, developed based on the symmetric Galerkin BIEs, is used for obtaining the fracture solutions at the arbitrary crack-front. The finite element method is used to model the uncracked global (built-up) structure for obtaining the stresses in an otherwise uncracked body. The solution for the cracked structural component is obtained in an iteration procedure, which alternates between FEM solution for the uncracked body, and the SGBEM solution for the crack in the local finite-sized subdomain. In addition, some crack growth models are used to… More >

  • Open Access


    SGBEM (for Cracked Local Subdomain) -- FEM (for uncracked global Structure) Alternating Method for Analyzing 3D Surface Cracks and Their Fatigue-Growth

    Z. D. Han1, S. N. Atluri1

    CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.6, pp. 699-716, 2002, DOI:10.3970/cmes.2002.003.699

    Abstract As shown in an earlier work, the FEM-BEM alternating method is an efficient and accurate method for fracture analysis. In the present paper, a further improvement is formulated and implemented for the analyses of three-dimensional arbitrary surface cracks by modeling the cracks in a local finite-sized subdomain using the symmetric Galerkin boundary element method (SGBEM). The finite element method is used to model the uncracked global (built-up) structure for obtaining the stresses in an otherwise uncracked body. The solution for the cracked structural component is obtained in an iteration procedure, which alternates between FEM solution for the uncracked body, and… More >

  • Open Access


    A Finite Element Study of the Influence of Graphite Nodule Characteristics on a Subsurface Crack in a Ductile Cast Iron Matrix under a Contact Load

    G. Suguinoshita1, C. H. Silva1, M. A. Luersen1, *

    CMES-Computer Modeling in Engineering & Sciences, Vol.117, No.1, pp. 59-71, 2018, DOI:10.31614/cmes.2018.01777

    Abstract This paper describes a study of the effects of graphite nodule characteristics on a subsurface crack in austempered ductile iron (ADI). A representative specimen of ADI, subjected to sliding contact load, is modeled using finite elements aiming to obtain the shear stress intensity factor (KII). The parameters varied were (i) the nodule diameter (two different values were considered), (ii) the distance between the nodule and the tip of the crack and (iii) the position of the load relative to the tip of the crack. The results of the numerical simulations show that the smaller diameter nodule has a larger influence… More >

  • Open Access


    Interaction Effect Analysis of Two Surface Cracks using S-version FEM

    Masanori Kikuchi1, Yoshitaka Wada2, Hitomi Suyama3, YuLong Li4

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.9, No.4, pp. 222-224, 2009, DOI:10.3970/icces.2009.009.222

    Abstract Prediction of fatigue crack growth in mechanical component is one of the most important problems to prevent catastrophic fracture accident. FEM is generally used for this purpose, but as crack shape changes during growing process, it is necessary to re-mesh for new crack shape. It is time consuming and is very difficult especially for 3-d. problem.
    In this study, S-version FEM[1][2] is employed to solve this problem, and fully automatic crack growth simulation system is made by combining with automatic mesh generationsystem. In the 3-d. field, crack tip stressconditionbecomes under mixed mode condition, and three stress intensity factor, KI,KII and… More >

  • Open Access


    The Bauschinger Effect on 3-D SIFs for Networks of Radial and Longitudinally-Coplanar Semi-Elliptical Internal Surface Cracks In Autofrettaged Pressurized Thick-Walled Cylinders

    Q. Ma1, C. Levy2, M. Perl3

    CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.2, pp. 95-110, 2008, DOI:10.3970/cmes.2008.029.095

    Abstract Networks of radial and longitudinally-coplanar, internal, surface cracks are typical in rifled, autofrettaged, gun barrels. In two previous papers, the separate effects of large arrays of either radial or longitudinally-coplanar semi-elliptical, internal, surface cracks in a thick-walled, cylindrical, pressure vessel under both ideal and realistic autofrettage were studied. When pressure is considered solely, radial crack density and longitudinal crack spacing were found to have opposing effects on the prevailing stress intensity factor, KIP. Furthermore, the addition of the negative stress intensity factor (SIF), KIA, resulting from the residual stress field due to autofrettage, whether ideal or realistic, tended to decrease… More >

  • Open Access


    Time-Dependent J-Integral Solution for Semi-elliptical Surface Crack in HDPE

    M. Bendouba1, A. Djebli1, A. Aid1, N. Benseddiq2, M. Benguediab3

    CMC-Computers, Materials & Continua, Vol.45, No.3, pp. 163-186, 2015, DOI:10.3970/cmc.2015.045.163

    Abstract This work focuses on a linear elastic analysis by the finite element method and the development of a shape function, commonly known as geometrical correction factor, for the case of semi-elliptical crack in a cylindrical rod. We used the same shape function to analyze the behavior of the rod in the case of a viscoelastic medium materialized by a polymeric material such as HDPE. A linear viscoelastic model calibrated from a relaxation test was developed and implemented in Abaqus. Results showed a relatively good performance, compared with finite element method. More >

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