D21 Evaluation Method of Heat Crack Initiation Condition Based on Tensile Fracture Criterion of Notched Specimens

2008 ◽  
Vol 2008.61 (0) ◽  
pp. 123-124
Author(s):  
Suguru KASHIWAGI ◽  
Akio SONODA ◽  
Shigeru HAMADA ◽  
Hiroshi NOGUCHI
Keyword(s):  
Crack Initiation ◽  
Fracture Criterion ◽  
Evaluation Method ◽  
Tensile Fracture ◽  
Notched Specimens ◽  
Initiation Condition

Influence of Perforation Parameter on Crack Initiation and Extending of Hydraulic Fracturing

2012 ◽  
Vol 594-597 ◽  
pp. 202-206 ◽  
Author(s):  
Min Zheng Jiang ◽  
Yang Li ◽  
Yi Ming Zhang ◽  
Tian Xue Jiang ◽  
Ming Xing Liu
Keyword(s):  
Crack Initiation ◽  
Hydraulic Fracturing ◽  
Mechanical Model ◽  
Fracture Criterion ◽  
Tensile Fracture ◽  
Low Permeability ◽  
Dynamic Effects ◽  
Low Permeability Reservoir ◽  
Initiation Pressure ◽  
Hole Effect

Widespread problem in hydraulic fracturing of low-permeability reservoir is difficulty of crack initiation of fracturing, high initiation pressure of fracturing put forward higher requirements of fracturing equipment. Low-permeability reservoir for the study, in the fluid-solid coupling conditions, established a low-permeability reservoir perforation mechanical model of stress, using numerical solution techniques, consider the dynamic effects, we can achieve the stress distribution at different stages: drilling, well cementation, perforation and fracturing in low-permeability reservoir. With rock tensile fracture criterion can determine the initiation location and initiation pressure. The results show that the lower the degree of pollution in perforating hole, the smaller the pressure from the crack initiation as well as the higher the degree of pollution in perforating hole, the larger the pressure from the crack initiation. Orientation, diameter and depth of perforating hole effect on crack initiation and extension are more significant.

The Area Fracture Criterion of Iso-εθ Line for Mixed Mode Crack

2012 ◽  
Vol 193-194 ◽  
pp. 708-711
Author(s):  
Si Li Chen ◽  
Tao Yu ◽  
Jian Jun Shi ◽  
Jie Huang ◽  
Kai He Dong
Keyword(s):  
Crack Initiation ◽  
Mixed Mode ◽  
Fracture Criterion ◽  
Shape Change ◽  
Crack Tip ◽  
Fracture Line ◽  
Mixed Mode Crack ◽  
Engineering Significance ◽  
Crack Initiation Angle ◽  
Predicted Values

In practice, the crack in some engineering materials is often compound crack. Therefore, it is important engineering significance to study on fracture problem. Based on the shape change energy near crack tip portion, the area fracture criterion of Iso-εθ line for compound crack was proposed. A crack initiation angle formula and the fracture criterion were established. The results showed that the theoretical predicted values and the measured values are consistent. The compound crack fracture line area of fracture criterion was established.Tthe formulas are easy to be derived and convenient to apply.

Mean Strain Effect on Crack Initiation Lives for Notched Specimens Under Biaxial Nonproportional Loading Paths

1997 ◽  
Vol 119 (1) ◽  
pp. 104-112 ◽  
Author(s):  
Ming-Chuen Yip ◽  
Yi-Ming Jen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Crack Initiation ◽  
Strain Effect ◽  
Nonproportional Loading ◽  
Notched Specimens ◽  
Loading Paths ◽  
The Mean ◽  
Mean Strain ◽  
Element Method

This paper discusses the mean strain effect on the crack initiation lives for notched specimens under biaxial nonproportional loading paths. Elastic-plastic finite element method was used to evaluate the local stresses and strains. Several prediction models related to the mean stress/strain effect were employed to correlate the experimental results with reference fatigue data for smooth specimens. It is found that Fatemi-Socie model gives good prediction for the present research with the assistance of finite element method. The stress behavior in this deflection-controlled tests is discussed in this study, and the failure surfaces are also examined after tests.

Study of Evaluation Method for Liquation Crack Initiation in the Haz of a Laser Weldment

2005 ◽  
Vol 49 (9-10) ◽  
pp. 49-57 ◽  
Author(s):  
M. Yamamoto ◽  
A. Takata ◽  
S. Kamikariya ◽  
K. Shinozaki ◽  
M. Shirai
Keyword(s):  
Crack Initiation ◽  
Evaluation Method

Failure Stress in Notched Paper Sheets

2013 ◽  
Vol 569-570 ◽  
pp. 417-424
Author(s):  
Carlos A. Mora Santos ◽  
Orlando Susarrey Huerta ◽  
Vicente Flores Lara ◽  
Jorge Bedolla Hernández ◽  
Maribel A. Mendoza Nuñez
Keyword(s):  
Crack Initiation ◽  
The Self ◽  
Stress Theory ◽  
Crack Initiation Stress ◽  
Notched Specimens ◽  
Random Array ◽  
Crack Mechanics ◽  
Theoretical Stress ◽  
Initiation Stress ◽  
Circular Notch

In this work the crack initiation stress of notched specimens of filter paper is studied. The paper in the microstructure has a random array in their fibers while macroscopically it behaves anisotropically. The self-affine crack mechanics is used to study the size effect in the tensile behavior of this kind of paper under the presence of several conditions of geometrical notches. While in the traditional fracture mechanics the crack initiation stress is a material parameter when is reached a critical level at the crack tip, in the self-affine crack mechanics, depends moreover of the resulting tortuosity of the crack. Four geometrical arrangements in two sizes we considered: centered circular notch, centered lineal notch, sided circular notches and without notch at 10 and 300 mm width with a relation 2a/w = 0.25 under the same loading conditions. In this, the without notch specimens present the higher stress, all other notched specimens presented a similar crack initiation stress about 1 % of difference among them, and the crack growth is not affected by the geometry of notch. In spite of this difference, no one of the specimens reach the theoretical stress concentration of 3 such as predicted the classical stress theory.

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