Influence of crack closure on the stress intensity factor in bending plates ? A classical plate solution

1992 ◽  
Vol 55 (1) ◽  
pp. 81-93 ◽  
Author(s):  
M. J. Young ◽  
C. T. Sun
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Closure ◽  
Bending Plates ◽  
Plate Solution

Study on the Stress Intensity Factor for Mixed Mode Surface Crack under Three Point Bending

2008 ◽  
Vol 33-37 ◽  
pp. 85-90
Author(s):  
Wei Xie ◽  
Qi Qing Huang ◽  
Masanori Kikuchi
Keyword(s):  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Energy Release Rate ◽  
Crack Closure ◽  
Release Rate ◽  
Mixed Mode ◽  
Three Point Bending ◽  
Closure Method

In the virtual crack closure method (VCCM), the energy release rate is computed based on the results of finite element calculation, and the stress intensity factor (SIF) is computed from the energy release rate. In this paper, the stress intensity factor of mixed-mode surface cracks under three point bending is studied by using the three dimensional modified virtual crack closure method (MVCCM). The modified virtual crack closure method is required to open one element face area whose shape is arbitrary and finite element widths are unequal across the crack front. The effect of the distance between the location of load and crack face, crack shape and crack depth to the stress intensity factor is also discussed, along with practical results and conclusions.

An Efficient Way to Characterize the Fatigue Crack Growth Based on Numerical Analysis

2009 ◽  
Vol 417-418 ◽  
pp. 653-656
Author(s):  
Ya Zhi Li ◽  
Jing He ◽  
Zi Peng Zhang
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Length ◽  
Crack Growth ◽  
Crack Closure ◽  
Load Ratio ◽  
Specimen Thickness

The behavior of plasticity induced fatigue crack closure (PICC) in middle tension specimen was analyzed by the elastic-plastic finite element method. For the constant-K (CK) loading cases, the opening stress intensity factor are independent of crack length. The level of increases with the maximal applied stress intensity factor for given load ratio and increases with for fixed . The in plane strain state is much smaller than that in plane stress state. The results under CK loadings can be deduced to constant amplitude cyclic loading case during which the load ratio, maximal load level, crack length and specimen thickness are all the factors affecting the crack closure effect. The phenomena revealed in the analysis are beneficial in understanding the driving force mechanism of the fatigue crack growth.

EFG Virtual Crack Closure Technique for the Determination of Stress Intensity Factor

2011 ◽  
Vol 250-253 ◽  
pp. 3752-3758 ◽  
Author(s):  
Xue Ping Chang ◽  
Jun Liu ◽  
Shi Rong Li
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Closure ◽  
Crack Opening ◽  
Crack Tip ◽  
Strain Energy Release ◽  
Virtual Crack Closure Technique ◽  
Opening Displacement ◽  
Closure Technique

The aim of this paper is to introduce a virtual crack closure technique based on EFG method for thread-shape crack. The cracked component is discretized and the displacement field is determined using a coupled FE/EFG method, by which EFG nodes are arranged in the vicinity of crack tip and FE elements in the remain part in order to improve computational efficiency. Two typical parameters, nodal force and crack opening displacement attached to crack tip are calculated by means of setting up an auxiliary FE zone around crack tip. Strain energy release rate (SERR), further stress intensity factor (SIF) are determined by the two parameters. The method to calculate SIF is named as virtual crack closure technique based on EFG method. It is showed by several numerical examples that using the method presented in this paper, SIF on the crack tip can be obtained accurately.

An Improved Shell Theory Applied for Failure Analysis of Pressure Vessels

2011 ◽  
Author(s):  
R. Liu ◽  
J. Zhao ◽  
X. J. Wu
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Closure ◽  
Shell Theory ◽  
Pressure Vessels ◽  
Element Analysis ◽  
Crack Face ◽  
Theoretical Formulation ◽  
Curvature Effects

Crack-face closure occurs physically at the compressive edges when a shell is subjected to bending loads. However, in traditional shell theories, crack closure effects are not concerned when evaluating the stress intensity factor (SIF). In reality, crack closure effects influence significantly the SIF. This article presents the theoretical and numerical analyses of crack-face closure effects on the stress intensity factor of shells under bending. The theoretical formulation is based on the shallow shell theory of Delale and Erdogan, incorporating the effects of crack-face closure, which are modeled by a line contact at the compressive edges of the crack faces. It is shown that due to curvature effects crack closure in shells may not occur on the entire length of the crack, depending on the nature of the bending loading and the geometry of the shell. To validate the theoretical solution finite element analysis (FEA) is also performed; the two results agree well. As an example, the stress intensity factor for a pressurized cylinder containing an axial crack is determined based on the improved shell theory which takes into account the effects of crack-face closure.

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