Maximum energy release rate distribution from a generalized 3D virtual crack extension method

1992 ◽  
Vol 42 (6) ◽  
pp. 961-969 ◽  
Author(s):  
P.W. Claydon
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Crack Extension ◽  
Maximum Energy ◽  
Extension Method ◽  
Rate Distribution ◽  
Virtual Crack Extension ◽  
Virtual Crack Extension Method ◽  
Maximum Energy Release

Virtual Crack Extension Method for Energy Release Rate Calculations in Flawed Thin Shell Structures

1987 ◽  
Vol 109 (1) ◽  
pp. 101-107 ◽  
Author(s):  
P. LeFort ◽  
H. G. deLorenzi ◽  
V. Kumar ◽  
M. D. German
Keyword(s):  
Finite Element Analysis ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Thin Shell ◽  
Crack Extension ◽  
Element Analysis ◽  
Extension Method ◽  
Virtual Crack Extension ◽  
Virtual Crack Extension Method

The calculation of the energy release rate, G, by the virtual crack extension method has been used extensively in the literature over the last few years. A formulation and implementation of the energy release rate for use with 8 and 9-noded isoparametric thin shell elements is described in this paper. The representation used in the paper allows the calculation of G either as an integral part of a finite element analysis or separately in a postprocessing program using the stress and strain data from a finite element analysis as input. The results presented in the paper are compared with those published in the literature for several elastic as well as elastic-plastic crack problems.

Analysis of Branched Interface Cracks

1990 ◽  
Vol 57 (4) ◽  
pp. 887-893 ◽  
Author(s):  
D. J. Mukai ◽  
R. Ballarini ◽  
G. R. Miller
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Interface Crack ◽  
Finite Length ◽  
Release Rate ◽  
Rate Ratio ◽  
Maximum Energy ◽  
Crack Branching ◽  
Maximum Energy Release ◽  
Branch Crack

A solution is presented for the problem of a finite length crack branching off the interface between two bonded dissimilar isotropic materials. Results are presented in terms of the ratio of the energy release rate of a branched interface crack to the energy release rate of a straight interface crack with the same total length. It is found that this ratio reaches a maximum when the interface crack branches into the softer material. Longer branches tend to have smaller maximum energy release rate ratio angles indicating that all else being equal, a branch crack will tend to turn back parallel to the interface as it grows.

Crack Tunneling in Cement Sheath of Hydrocarbon Well

2015 ◽  
Vol 83 (1) ◽  
Author(s):  
Zhengjin Wang ◽  
Yucun Lou ◽  
Zhigang Suo
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Maximum Energy ◽  
Large Area ◽  
Annular Gap ◽  
Small Cracks ◽  
Cement Sheath ◽  
Well Cement ◽  
Maximum Energy Release

In a hydrocarbon well, cement fills the annular gap between two steel casings or between a steel casing and rock formation, forming a sheath that isolates fluids in different zones of the well. For a well as long as several kilometers, the cement sheath covers a large area and inevitably contains small cracks. The cement sheath fails when a small crack grows and tunnels through the length of the well. We calculate the energy release rate at a steady-state tunneling front as a function of the width of the tunnel. So long as the maximum energy release rate is below the fracture energy of the cement, tunnels of any width will not form. This failsafe condition requires no measurement of small cracks, but depends on material properties and loading conditions. We further show that the critical load for tunneling reduces significantly if the cement/casing and cement/formation interfaces slide.

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