A finite element calculation of stress intensity factors by a modified crack closure integral

Rybicki, E.F.; Kanninen, M. F.

doi:10.1016/0013-7944(77)90013-3

Cited by 1,976 publications

(755 citation statements)

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“…The stress intensity factors were evaluated using virtual crack closure integral method [50] Figure 8 were considered. Table 2 gives the relative error in the stress intensity factor obtained by using three different methods.…”

Section: Aα χmentioning

confidence: 99%

Multiscale enrichment based on partition of unity

Fish¹,

Yuan²

2004

Numerical Meth Engineering

139

110

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A new Multiscale Enrichment method based on the Partition of Unity (MEPU) method is presented. It is a synthesis of mathematical homogenization theory and the Partition of Unity method. Its primary objective is to extend the range of applicability of mathematical homogenization theory to problems where scale separation may not be possible. MEPU is perfectly suited for enriching the coarse scale continuum descriptions (PDEs) with fine scale features and the quasi-continuum formulations with relevant atomistic data. Numerical results show that it provides a considerable improvement over classical mathematical homogenization theory and quasi-continuum formulations.

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Section: Aα χmentioning

confidence: 99%

Multiscale enrichment based on partition of unity

Fish¹,

Yuan²

2004

Numerical Meth Engineering

139

110

View full text Add to dashboard Cite

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“…The method, which is detailed by Rybicki and Kanninen (1977), is based on the Irwin representation of energy release rate for self-similar crack extension given in (14). The method involves expressing the mode I and mode II portions of Gtotal(see (14)) in terms of nodal forces ahead of the crack tip and nodal displacements behind the tip.…”

Section: Virtual Crack Closure Techniquementioning

confidence: 99%

Separation of crack extension modes in orthotropic delamination models

Beuth

1996

Int J Fract

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In the analysis of an interface crack between dissimilar elastic materials, the mode of crack extension is typically not unique, due to oscillatory behavior of near-tip stresses and displacements. This behavior currently limits the applicability of interfacial fracture mechanics as a means to predict delamination in layered materials. The Virtual Crack Closure Technique (VCCT) is a method used to extract mode I and mode II energy release rates from numerical fracture solutions. The mode of crack extension extracted from an oscillatory solution using the VCCT is not unique due to the dependence of mode on the virtual crack extension length, A.In this work, a method is presented for using the VCCT to extract A-independent crack extension modes for the case of an interface crack between two in-plane orthotropic materials.The method does not involve altering the analysis to eliminate its oscillatory behavior. Instead, it is argued that physically reasonable, A-independent modes of crack extension can be extracted from oscillatory solutions. Knowledge of near-'tip fields is used to determine the explicit A dependence of energy release rate parameters. Energy release rates are then defined that are separated from the oscillatory dependence on A. A modified VCCT using these energy release rate definitions is applied to results from finite element analyses, showing that A-independent modes of crack extension result. The modified technique has potential as a consistent method for extracting crack extension modes from numerical solutions. The A-independent modes extracted using this technique can also serve as guides for testing .the convergence of finite element models. Direct applications of this work include the analysis of planar composite delamination problems, where plies or debonded laminates are modeled as in-plane orthotropic materials.

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“…Numerical analysis techniques include the Virtual Crack Closure Technique (Rybicki and Kanninen, 1977;Krueger, 2004) and the use of interface elements, which are specialised finite elements placed along potential failure planes and used to simulate crack growth (Camanho et al, 2003;Jiang et al, 2007;Hallett, 2007). A key advantage of interface elements is that they can encompass both strength based damage initiation criteria and fracture based crack propagation criteria.…”

Section: Figure 2: the Structural Design Process For Tidal Turbine Blmentioning

confidence: 99%

Advanced numerical modelling techniques for the structural design of composite tidal turbine blades

Harper

Hallett

2015

Ocean Engineering

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Abstract:Tidal Stream turbine blades must withstand both extreme one-off loads and severe fatigue loads during their 20-25 year required lifetimes in harsh marine environments. This necessitates the use of high-strength fibre reinforced composite materials to provide the required stiffness, strength and fatigue life, as well as resistance to corrosion, whilst minimising the mass of material required for blade construction and allowing its geometric form to provide the required hydrodynamic performance. Although composites provide superior performance to metals, potential failure mechanisms are more complicated and difficult to predict. A dominant failure mechanism is interfacial failure (delamination) between the composite layers (plies). This paper demonstrates how the development of numerical techniques for modelling the growth of interfacial cracks can aid the design process, allowing the effects on crack growth from potential manufacturing defects and the effect of stacking sequence of composite plies to be analysed. This can ultimately lead to reduced design safety margins and a reduction in the mass of material required for blade manufacture, essential for reducing lifecycle costs. Although the examples provided in this article are specific to tidal turbine blades, the analysis techniques are applicable to all composite structures where fatigue delamination is a primary failure concern.

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A finite element calculation of stress intensity factors by a modified crack closure integral

Cited by 1,976 publications

References 10 publications

Multiscale enrichment based on partition of unity

Multiscale enrichment based on partition of unity

Separation of crack extension modes in orthotropic delamination models

Advanced numerical modelling techniques for the structural design of composite tidal turbine blades

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