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  • Open Access

    ARTICLE

    Cell Method Analysis of Crack Propagation in Tensioned Concrete Plates

    E. Ferretti1

    CMES-Computer Modeling in Engineering & Sciences, Vol.54, No.3, pp. 253-282, 2009, DOI:10.3970/cmes.2009.054.253

    Abstract In this study, the problem of finding the complete trajectory of propagation and the limiting load in plates with internal straight cracks is extended to the non-linear field. In particular, results concerning concrete plates in bi-axial tensile loading are shown. The concrete constitutive law adopted for this purpose is monotonic non-decreasing, as following according to previous studies of the author on monotonic mono-axial loading. The analysis is performed in a discrete form, by means of the Cell Method (CM). The aim of this study is both to test the new concrete constitutive law in biaxial More >

  • Open Access

    ARTICLE

    Modeling Intergranular Crack Propagation in Polycrystalline Materials

    M.A.Arafin1, J.A.Szpunar2

    CMC-Computers, Materials & Continua, Vol.14, No.2, pp. 125-140, 2009, DOI:10.3970/cmc.2009.014.125

    Abstract A novel microstructure, texture and grain boundary character based model has been proposed to simulate the intergranular crack propagation behavior in textured polycrystalline materials. The model utilizes the Voronoi algorithm and Monte Carlo simulations to construct the microstructure with desired grain shape factor, takes the texture description of the materials to assign the orientations of the grains, evaluates the grain boundary character based on the misorientation angle - axis calculated from the orientations of the neighboring grains, and takes into account the inclination of grain boundaries with respect to the external stress direction. Markov Chain More >

  • Open Access

    ARTICLE

    The Influence of Structural Defect on Mechanical Properties and Fracture Behaviors of Carbon Nanotubes

    Hsien-Chie Cheng1, Yu-Chen Hsu2, Wen-Hwa Chen2

    CMC-Computers, Materials & Continua, Vol.11, No.2, pp. 127-146, 2009, DOI:10.3970/cmc.2009.011.127

    Abstract Due to the limitation of fabrication technologies nowadays, structural or atomistic defects are often perceived in carbon nanotubes (CNTs) during the manufacturing process. The main goal of the study aims at providing a systematic investigation of the effects of atomistic defects on the nanomechanical properties and fracture behaviors of single-walled CNTs (SWCNTs) using molecular dynamics (MD) simulation. Furthermore, the correlation between local stress distribution and fracture evolution is studied. Key parameters and factors under investigation include the number, type (namely the vacancy and Stone-Wales defects), location and distribution of defects. Results show that the nanomechanical More >

  • Open Access

    ARTICLE

    A Study of Damage Identification and Crack Propagation in Concrete Beams

    A. Brasiliano1, W.R. Souza2, G.N. Doz3, J.L.V. Brito4

    Structural Durability & Health Monitoring, Vol.4, No.2, pp. 53-66, 2008, DOI:10.3970/sdhm.2008.004.053

    Abstract It can be observed that usually, during structures useful life they are submitted to deterioration processes that, depending on the intensity, may affect their performance and load capacity and, as a result, their safety. In this case, it is necessary to accomplish an inspection in order to evaluate the conditions of the structure and to locate and quantify the intensity of the damage. Another important point is to study the behavior of brittle material beams with cracks, as an attempt of understanding the rupture mechanism and crack propagation phenomenon. In this paper, the Residual Error More >

  • Open Access

    ARTICLE

    Crack Propagation in Concrete Using Meshless Method

    N. Sageresan, R. Drathi

    CMES-Computer Modeling in Engineering & Sciences, Vol.32, No.2, pp. 103-112, 2008, DOI:10.3970/cmes.2008.032.103

    Abstract Crack propagation in concrete is computed with a simplified meshless method. The material is elastic of Neo-Hookian type until fracture. Then a discrete cohesive crack method is used. In the cohesive crack method, cohesive segments are introduced at the meshless nodes. No representation of the crack surface is needed. The method is well-suited for concrete since concrete develops many cracks. Mesh independent results are obtained due to the cohesive model that takes into account the correct energy dissipation during crack opening. We show the accuracy of our method by comparison to experimental data. More >

  • Open Access

    ARTICLE

    Masonry Walls under Shear Test: a CM Modeling

    E. Ferretti1, E. Casadio, A. Di Leo1

    CMES-Computer Modeling in Engineering & Sciences, Vol.30, No.3, pp. 163-190, 2008, DOI:10.3970/cmes.2008.030.163

    Abstract In this study, the Cell Method (CM) is applied in order to investigate the failure mechanisms of masonry walls under shear force. The direction of propagation is computed step-wise by the code, and the domain is updated by means of a propagation technique of intra-element nodal relaxation with re-meshing. The crack extension condition is studied in the Mohr/Coulomb plane, using the criterion of Leon. The main advantage of using the CM for numerical analyses of masonry is that the mortar, the bricks and the interfaces between mortar and bricks can be modeled without any need… More >

  • Open Access

    ARTICLE

    An Efficient Model for Crack Propagation

    S.S. Xu, Y. Dong, Y. Zhang

    CMES-Computer Modeling in Engineering & Sciences, Vol.30, No.1, pp. 17-26, 2008, DOI:10.3970/cmes.2008.030.017

    Abstract A meshless method for arbitrary crack growths is presented. The new method is based on a local partition of unity by introducing additional degrees of freedom that determine the opening of the crack. The crack is modeled with overlapping crack segments located at the nodes. The crack segments are rotated at directional changes of the principal tensile stress such that smearing of the crack is avoided. Such smearing occurs in fixed crack method probably because of inaccurate stress state around the crack tip when the crack propagates. The key feature of our method is that More >

  • Open Access

    ARTICLE

    Two-dimensional Numerical Estimation of Stress Intensity Factors and Crack Propagation in Linear Elastic Analysis

    Abdulnaser M. Alshoaibi1,2, M. S. A. Hadi2, A. K. Ariffin2

    Structural Durability & Health Monitoring, Vol.3, No.1, pp. 15-28, 2007, DOI:10.3970/sdhm.2007.003.015

    Abstract An adaptive finite element method is employed to analyze two-dimensional linear elastic fracture problems. The mesh is generated by the advancing front method and the norm stress error is taken as a posteriori error estimator for the h-type adaptive refinement. The stress intensity factors are estimated by a displacement extrapolation technique. The near crack tip displacements used are obtained from specific nodes of natural six-noded quarter-point elements which are generated around the crack tip defined by the user. The crack growth and its direction are determined by the calculated stress intensity factors as the maximum circumference More >

  • Open Access

    ARTICLE

    Numerical Simulation of Dynamic Elasto Visco-plastic Fracture Using Moving Finite Element Method

    T. Fujimoto1 and T. Nishioka1

    CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.2, pp. 91-102, 2006, DOI:10.3970/cmes.2006.011.091

    Abstract In the dynamic fracture of metallic material, some cracks propagate with the incidence of plastic deformation, and distinct plastic strain remains near the post-propagation area. In order to elucidate these dynamic nonlinear fracture processes, the moving finite element method is developed for nonlinear crack propagation. The T* integral is used as the parameter to estimate crack tip condition. First, the effect of material viscosity and crack propagation velocity have been discussed based on the numerical results for fracture under pure mode I high speed loading. Under mixed mode loading, numerical simulations for fracture path prediction More >

  • Open Access

    ARTICLE

    Numerical Investigation of the Multiple Dynamic Crack Branching Phenomena

    T. Nishioka1, S. Tchouikov1, T. Fujimoto1

    CMC-Computers, Materials & Continua, Vol.3, No.3, pp. 147-154, 2006, DOI:10.3970/cmc.2006.003.147

    Abstract In this study, phenomena of multiple branching of dynamically propagating crack are investigated numerically. The complicated paths of cracks propagating in a material are simulated by moving finite element method based on Delaunay automatic triangulation (MFEM BODAT), which was extended for such problems. For evaluation of fracture parameters for propagating and branching cracks switching method of the path independent dynamic J integral was used. Using these techniques the generation phase simulation of multiple dynamic crack branching was performed. Various dynamic fracture parameters, which are almost impossible to obtain by experimental technique alone, were accurately evaluated. More >

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