Elastic-Plastic Constraints Analysis for Hole-Edge Crack

2015 ◽  
Vol 1095 ◽  
pp. 505-509
Author(s):  
Yi Qin Xie ◽  
Zhong Xian Wang ◽  
Yan Qing Zhang
Keyword(s):  
Edge Crack ◽  
Crack Tip ◽  
Shielding Effect ◽  
Round Hole ◽  
Elastic Plastic ◽  
Amplification Effect ◽  
Hole Edge ◽  
Fracture Theory ◽  
Crack Tip Constraint ◽  
Diamond Hole

This paper mainly conducts an elastic-plastic constraint analysis on rectangular plate specimens with hole-edge crack under remote uniaxial uniformly distributed load by usingJ-A2elastic-plastic fracture theory. In order to analyze the effect of orifice on elastoplastic stress field of hole-edge crack tip, this paper calculates a series of round hole-edge crack, diamond hole-edge crack and corresponding pure crack models. The interference effects of the orifice shape on elastic-plastic J integral and crack constraint parameterA2are discussed. The results show that: the orifice has an amplification effect on the fracture driving force (J-integral), and this amplification effect in elastic-plastic is smaller than that in elastic; the orifice has a shielding effect on the crack tip constraint (A2parameter), and this shielding effect gradually weaken with the crack increasing.

Analysis and Simulation of Elastic-Plastic Fracture Parameters at Crack Tip under Biaxial Loading and Uniaxial Loading

2012 ◽  
Vol 166-169 ◽  
pp. 2883-2886 ◽  
Author(s):  
Zhong Xian Wang ◽  
Rui Liu
Keyword(s):  
Biaxial Loading ◽  
Crack Tip ◽  
Tensile Specimen ◽  
Biaxial Stress ◽  
Fracture Parameter ◽  
Single Edge ◽  
Elastic Plastic ◽  
Finite Distance ◽  
Fracture Theory ◽  
Loading Modes

Based on the J-A2 two-parameter elastic-plastic fracture theory and finite element numerical method, the elastic-plastic stress field ahead of the crack tip in a single edge cracked eccentric tensile specimen (the load-line is at a finite distance from the crack tip) was analyzed and compared with that of a center cracked large plate under biaxial loading. By using the Ritchie-Knott-Rice fracture criterion, a transformational relation between the two loading modes was obtained based on the J-A2 equivalent principle. As a result, the fracture parameter determined from a single edge cracked eccentric tensile specimen can be applied to the fracture analysis of a center cracked plate under biaxial stress.

Investigation on Constraint Effect of a Reactor Pressure Vessel Subjected to Pressurized Thermal Shocks

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Guian Qian ◽  
Markus Niffenegger
Keyword(s):  
Fracture Mechanics ◽  
Pressure Vessel ◽  
Plastic Material ◽  
Crack Tip ◽  
Constraint Effect ◽  
Elastic Plastic ◽  
Elastic Plastic Material ◽  
Crack Tip Constraint ◽  
Reactor Pressure ◽  
Thermal Shocks

The integrity of a reactor pressure vessel (RPV) related to pressurized thermal shocks (PTSs) has been extensively studied. This paper introduces the method of using fracture mechanics for the integrity analysis of a RPV subjected to PTS transients. A 3-D finite element (FE) model is used to perform thermal and fracture mechanics analyses by considering both elastic and elastic–plastic material models. The results show that the linear elastic analysis leads to a more conservative result than the elastic–plastic analysis. The variation of the T-stress and Q-stress (crack tip constraint loss) of a surface crack in a RPV subjected to PTSs is studied. A shallow crack is assumed in the RPV and the corresponding constraint effect on fracture toughness of the material is quantified by the K–T method. The safety margin of the RPV is larger based on the K–T approach than based only on the K approach. The J–Q method with the modified boundary layer formulation (MBL) is used for the crack tip constraint analysis by considering elastic–plastic material properties. For all transient times, the real stress is lower than that calculated from small scale yielding (SSY) due to the loss of crack tip constraint.

J-Integral and Plastic Limit Load of Hole-Edge Crack in Plate under Biaxial Loadings

2014 ◽  
Vol 881-883 ◽  
pp. 1412-1415
Author(s):  
Yan Qing Zhang ◽  
Zhong Xian Wang ◽  
Wei Xu
Keyword(s):  
Edge Crack ◽  
Load Ratio ◽  
Limit Load ◽  
Fe Analysis ◽  
J Integral ◽  
Plastic Limit ◽  
Elastic Plastic ◽  
Hole Edge ◽  
Biaxial Load ◽  
Plastic Limit Load

Elastic-plastic J-integral and plastic limit load were described by finite element (FE) analysis for single hole-edge crack in plate under far field biaxial load. In this paper, the effect of biaxial load ratio (from -1 to 1) on elastic-plastic J-integral and plastic limit load was studied, the values of coefficient h1 for J-integral engineering estimation formulas were given and the effect of material hardening on plastic limit load was discussed. The result obtained from this work provides reference for fracture evaluation, so it can be used in engineering accurately and expediently.

The Effects of Nonproportional Loading on the Elastic-Plastic Crack-Tip Fields

2016 ◽  
Vol 853 ◽  
pp. 83-87 ◽  
Author(s):  
Zhao Yu Jin ◽  
Xin Wang ◽  
Dun Ji Yu ◽  
Xu Chen
Keyword(s):  
Stress Field ◽  
Outer Boundary ◽  
Crack Tip ◽  
Loading Path ◽  
Small Scale ◽  
Proportional Loading ◽  
Nonproportional Loading ◽  
Elastic Plastic ◽  
Loading Paths ◽  
Crack Tip Constraint

In this paper, the loading path effects on the plane strain elastic-plastic crack-tip stress field are investigated computationally. Three different loading sequences include one proportional loading and two non-proportional loading paths are applied to the modified boundary layer (MBL) model under small-scale yielding conditions. For the same external displacement field applied at the outer boundary of the MBL model, the mode I K field and T-stress field combined as the different loading paths are applied to investigate the influence of the nonproportional loading. The results show that for either the compressive or tensional T-stress, the loading path which applied K field followed by T field generates the lower crack-tip constraint. There is only slightly difference between the proportional loading path and that with the T-stress field following by K field. The results show that it is very important to include the load sequence effects in fracture analysis when dealing with nonproportional loading conditions.

Investigation on Constraint Effect of a Reactor Pressure Vessel Subjected to Pressurized Thermal Shocks

2013 ◽  
Author(s):  
Guian Qian ◽  
Markus Niffenegger
Keyword(s):  
Fracture Mechanics ◽  
Pressure Vessel ◽  
Plastic Material ◽  
Crack Tip ◽  
Constraint Effect ◽  
Elastic Plastic ◽  
Elastic Plastic Material ◽  
Crack Tip Constraint ◽  
Reactor Pressure ◽  
Thermal Shocks

The integrity of a reactor pressure vessel (RPV) related to pressurized thermal shocks (PTSs) has been extensively studied. This paper introduces the method of using fracture mechanics for the integrity analysis of a RPV subjected to PTS transients. A 3-D finite element (FE) model is used to perform thermal and fracture mechanics analyses by considering both elastic and elastic-plastic material models. The results show that the linear elastic analysis leads to a more conservative result than the elastic-plastic analysis. The variation of the T-stress and Q-stress (crack tip constraint loss) of a surface crack in a RPV subjected to PTSs is studied. A shallow crack is assumed in the RPV and the corresponding constraint effect on fracture toughness of the material is quantified by the K-T method. The safety margin of the RPV is larger based on the K-T approach than only based on the K approach. The J-Q method with the modified boundary layer formulation (MBL) is used for the crack tip constraint analysis by considering elastic-plastic material properties. For all transient times, the real stress is lower than that calculated from small scale yielding (SSY) due to the loss of crack tip constraint.

Crack Tip Constraint Under Biaxial Loading in Elastic-Plastic Materials

2010 ◽  
Author(s):  
Z. X. Wang ◽  
Jian-ye Huang ◽  
Y. J. Chao ◽  
P. S. Lam
Keyword(s):  
Driving Force ◽  
Enhancement Factor ◽  
Structural Integrity ◽  
Biaxial Loading ◽  
Crack Tip ◽  
Element Analysis ◽  
Crack Driving Force ◽  
Integrity Assessment ◽  
Elastic Plastic ◽  
Crack Tip Constraint

Crack tip constraint is known to affect the fracture resistance of materials. The effect of biaxial loading on a center crack in an X100 steel plate has been investigated. The crack driving force and the constraint parameter are estimated based on the two-parameter J-A2 theory in elastic-plastic fracture mechanics with the aid of finite element analysis. The center-cracked plate is subject to various degrees of biaxiality (defined as the ratio of the transverse stress parallel to the crack and the opening stress normal to the crack). Using the constraint parameter (A2) in uniaxial loading condition as a reference value, a Constraint Enhancement Factor is introduced to facilitate the investigation of crack tip constraint under biaxial loading. The analysis carried out in this paper has established a relationship between the Constraint Enhancement Factor and the biaxiality. With the J-A2 fracture model, the critical applied load and the critical crack driving force can be expressed as functions of biaxial loading ratio. The methodology and analysis results can be used in structural integrity assessment of a pressure vessel or piping which contains a crack under biaxial loading.

Analysis of 316H Creep Crack Initiation Data at 550℃ using A Crack Tip Constraint Parameter

2021 ◽  
pp. 107746
Author(s):  
Seung-Ho Lee ◽  
Hyun-Woo Jung ◽  
Yun-Jae Kim ◽  
Kamran Nikbin ◽  
Robert A. Ainsworth
Keyword(s):  
Crack Initiation ◽  
Crack Tip ◽  
Creep Crack ◽  
Crack Tip Constraint
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