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.

scholarly journals Shear and foundation effects on crack root rotation and mode-mixity in moment- and force-loaded single cantilever beam sandwich specimen

2018 ◽  
Vol 52 (18) ◽  
pp. 2537-2547 ◽  
Author(s):  
Vishnu Saseendran ◽  
Leif A Carlsson ◽  
Christian Berggreen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Energy Release Rate ◽  
Energy Release ◽  
Cantilever Beam ◽  
Release Rate ◽  
Beam Specimen ◽  
Mode Mixity ◽  
Element Analysis ◽  
Fracture Specimens

Foundation effects play a crucial role in sandwich fracture specimens with a soft core. Accurate estimation of deformation characteristics at the crack front is vital in understanding compliance, energy release rate and mode-mixity in fracture test specimens. Beam on elastic foundation analysis of moment- and force-loaded single cantilever beam sandwich fracture specimens is presented here. In addition, finite element analysis of the single cantilever beam specimen is conducted to determine displacements, rotations, energy release rate and mode-mixity. Based on finite element analysis, a foundation modulus is proposed that closely agrees with the numerical compliance and energy release rate results for all cases considered. An analytical expression for crack root rotation of the loaded upper face sheet provides consistent results for both loading configurations. For the force-loaded single cantilever beam specimen (in contrast to the moment-loaded case), it was found that the crack length normalized energy release rate and the mode-mixity phase angle increase strongly as the crack length decreases, a result of increased dominance of shear loading.

scholarly journals Finite Element Analysis for Interfacial Crack in Piezoelectric Composite under Impact Loading

2012 ◽  
Vol 21 (1) ◽  
pp. 096369351202100
Author(s):  
Liang Wang ◽  
Rui-Xiang Bai ◽  
Hao-Ran Chen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Impact Loading ◽  
Crack Surface ◽  
Piezoelectric Composite ◽  
Element Analysis ◽  
Piezoelectric Composites

In this paper, a nonlinear finite element analysis of impact interfacial fracture for a piezoelectric composite is provided. The Newmark method was used to solve the dynamics equation. Virtual crack closure technique is to evaluate the energy release rate of crack tip. Contact elements were set up on crack surface and in the area in contact under impact loading to prevent the penetration between PZT and composite. The response curves of the energy release rate are obtained for piezoelectric composites. Numerical results are provided to show the effect of the piezoelectricity, the applied voltage, the stack sequence of composites and the contact of crack surface on the resulting dynamic energy release rate of piezoelectric composites.

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