A Finite Element Calculation of Stress Intensity Factors by a Modified Crack Closure Integral

Applied Solid Mechanics Section, Battelle's Columbus Laboratories, Columbus, OH 43201, U.S.A.
Engineering Fracture Mechanics (Impact Factor: 1.77). 01/1977; 9(4):931-938. DOI: 10.1016/0013-7944(77)90013-3


An efficient technique for evaluating stress intensity factors is presented. The method, based on the crack closure integral, can be used with a constant strain finite element stress analysis and a coarse grid. The technique also permits evaluation of both Mode I and Mode II stress intensity factors from the results of a single analysis. Example computations are performed for a double cantilever beam test specimen, a finite width strip with a central crack, and a pin loaded circular hole with radial cracks. Close agreement between numerical results given by this approach and reference solutions were found in all cases.

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    • "Traditionally, the study of delaminations is split into two distinct phenomena: the initiation of the crack and the ensuing propagation, where the latter is based on formulae of a pre-existing crack. The virtual crack closure technique (VCCT) proposed by Rybicki and Kanninen [4] is often used for predicting delamination growth. However, in the finite element method (FEM), VCCT results are dependent on the mesh in front of the crack tip and a pre-defined location of a crack is required. "
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    ABSTRACT: The Refined Zigzag Theory is applied to the modeling of delaminations in laminated composites. The commonly used cohesive zone approach is adapted for use within a continuum mechanics model, and then used to predict the onset and propagation of delamination in five cross-ply composite beams. The resin-rich area between individual composite plies is modeled explicitly using thin, discrete layers with isotropic material properties. A damage model is applied to these resinrich layers to enable tracking of delamination propagation. The displacement jump across the damaged interfacial resin layer is captured using the zigzag function of the Refined Zigzag Theory. The overall model predicts the initiation of delamination to within 8% compared to experimental results and the load drop after propagation is represented accurately.
    Report number: NASA/TM-2015-218808
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    • "Various procedures exist in the literature for the mode separation. Most of them are based on the differences between moments [6], displacements [13] or bending stiffnesses [14] of the two arms of the joint. However, the differences between moments or displacements are applicable only for symmetric specimens. "
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    ABSTRACT: This paper presents new analytical model of asymmetric mixed-mode bending (MMB) specimen of adhesively bonded pultruded GFRP joints. An easily applicable relationship for the calculation of the strain energy release rate of the asymmetric MMB specimens is proposed based on the beam theory. The model is capable to analyze stacking sequence as well as various crack propagation paths. In the paper the effect of the various fiber bridging length and different crack propagation paths is analyzed analytically and supported by experimental results. The methodology and results presented in this paper could be utilized for the design of both joint geometry and lay-up of the laminates constituting the joint or for the prediction of the fracture behavior of such structures.
    Frattura ed Integrità Strutturale 10/2015; 9(34). DOI:10.3221/IGF-ESIS.34.23 · 0.73 Impact Factor
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    • "Various procedures exist in the literature for the mode separation. Most of them are based on the differences between moments [23], displacements [29] or bending stiffness [30] of the two arms of the joint. A first attempt for the modeling of the MMB partition by FEM simulations has been recently presented by [31]. "
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    ABSTRACT: This paper presents a semi-analytical methodology for the fracture mechanics assessment of asymmetric adhesively bonded composite joints. The method is based on the classical lamination theory, the simple beam theory and the extended global method. Experimental results obtained from quasi-static mixed-Mode bending (MMB) tests of adhesively bonded glass fiber reinforced polymer (GFRP) laminates were used for the validation of the introduced methodology. The main advantage of the proposed methodology is the ability of taking into account the fiber bridging effects as well as the arbitrariness of the adherend stacking sequence in a distance from the crack propagation path.
    Engineering Fracture Mechanics 08/2015; 147. DOI:10.1016/j.engfracmech.2015.08.040 · 1.77 Impact Factor
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