Numerical calculation of energy release rates by virtual crack closure technique

2004 ◽  
Vol 18 (11) ◽  
pp. 1996-2008 ◽  
Author(s):  
Yoon-Suk Chang ◽  
Jae-Boong Choi ◽  
Young-Jin Kim ◽  
Genki Yagawa
Keyword(s):  
Numerical Calculation ◽  
Energy Release ◽  
Crack Closure ◽  
Virtual Crack Closure Technique ◽  
Release Rates ◽  
Closure Technique ◽  
Energy Release Rates

Quarter-Point Elements Are Unnecessary for the VCCT

2020 ◽  
Vol 87 (8) ◽  
Author(s):  
Elad Farkash ◽  
Leslie Banks-Sills
Keyword(s):  
Stress Intensity ◽  
Energy Release ◽  
Crack Closure ◽  
Stress Intensity Factors ◽  
Virtual Crack Closure Technique ◽  
Intensity Factors ◽  
Release Rates ◽  
Closure Technique ◽  
Established Method ◽  
Energy Release Rates

Abstract The virtual crack closure technique (VCCT) is a well-established method for determining energy release rates and stress intensity factors in homogeneous, isotropic materials. It has been implemented with four-noded, eight-noded, quarter-point, and other higher order elements. It is most convenient and accurate when used with eight-noded, isoparametric elements. VCCT produces less accurate results when used with quarter-point elements. Yet, this method continues to be employed with quarter-point elements. It is strongly recommended to use VCCT with regular eight-noded elements. Three examples will be presented to illustrate the inaccuracy when using quarter-point elements with VCCT.

MODIFIED VIRTUAL CRACK-CLOSURE TECHNIQUE USING SPECTRAL ELEMENT METHOD

2007 ◽  
Vol 04 (01) ◽  
pp. 109-139 ◽  
Author(s):  
A. KUMAR ◽  
S. GOPALAKRISHNAN ◽  
A. CHAKRABORTY
Keyword(s):  
Energy Release ◽  
Crack Closure ◽  
Spectral Element Method ◽  
Strain Energy Release ◽  
Spectral Element ◽  
Release Rates ◽  
Element Size ◽  
Energy Release Rates ◽  
Crack Tip Element ◽  
Element Method

This paper presents a general Chebyshev Spectral Element Method (CSEM) for obtaining strain-energy release rates for crack growth in two-dimensional isotropic materials. The procedure uses virtual crack-closure method. This method is developed for different orders of CSEM and suitable expressions for energy release rates are obtained. These expressions are evaluated by applying them to two Mode-I and two Mixed-mode problems. Two different classes of spectral elements (SEs) are formulated using Chebyshev interpolating functions, the inconsistent conventional SE formulation and the field consistent SE formulation. The convergence is investigated using both the formulations. A relative study on the efficiency of the CSEM with increasing order of polynomials is clearly brought out. The effect of crack-tip element size is also studied. It is observed that field consistent formulation always gives better results compared to inconsistent formulation. Comparisons with results from the literature for these problems show the efficiency of the CSEM.

scholarly journals Energy release rate of the fiber/matrix interface crack in UD composites under transverse loading: debond-debond and debond-free boundary interactions

2019 ◽  
Author(s):  
Luca Di Stasio ◽  
Janis Varna ◽  
Zoubir Ayadi
Keyword(s):  
Energy Release ◽  
Finite Thickness ◽  
Fiber Content ◽  
J Integral ◽  
Transverse Loading ◽  
Release Rates ◽  
Closure Technique ◽  
Loading Direction ◽  
Energy Release Rates ◽  
Fiber Matrix

The effects of crack shielding, finite thickness of the composite and fiber content on fiber/matrix debond growth in thin unidirectional composites are investigated analyzing Representative Volume Elements (RVEs) of different ordered microstructures. Debond growth is characterized by estimation of the Energy Release Rates (ERRs) in Mode I and Mode II using the Virtual Crack Closure Technique (VCCT) and the J-integral. It is found that increasing fiber content, a larger distance between debonds in the loading direction and the presence of a free surface close to the debond have all a strong enhancing effect on the ERR. The presence of fully bonded fibers in the composite thickness direction has instead a constraining effect, and it is shown to be very localized. An explanation of these observations is proposed based on mechanical considerations.

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