Elastic–plastic crack driving force for tubular X-joints with mismatched welds

2005 ◽  
Vol 27 (9) ◽  
pp. 1419-1434 ◽  
Author(s):  
X. Qian ◽  
Robert H. Dodds ◽  
Y.S. Choo
Keyword(s):  
Driving Force ◽  
Crack Driving Force ◽  
Elastic Plastic

J-integral and crack driving force in elastic–plastic materials

2008 ◽  
Vol 56 (9) ◽  
pp. 2876-2895 ◽  
Author(s):  
N SIMHA ◽  
F FISCHER ◽  
G SHAN ◽  
C CHEN ◽  
O KOLEDNIK
Keyword(s):  
Driving Force ◽  
J Integral ◽  
Crack Driving Force ◽  
Elastic Plastic ◽  
Plastic Materials ◽  
Elastic Plastic Materials

Assessment of Fully Plastic J and C*-Integral Solutions for Application to Elastic-Plastic Fracture and Creep Crack Growth

1993 ◽  
Vol 115 (3) ◽  
pp. 228-234 ◽  
Author(s):  
D. R. Lee ◽  
J. M. Bloom
Keyword(s):  
Finite Element ◽  
Crack Growth ◽  
Driving Force ◽  
Creep Crack Growth ◽  
J Integral ◽  
Finite Element Program ◽  
Hardening Material ◽  
Crack Driving Force ◽  
Elastic Plastic ◽  
Creep Crack

A critical part of the assessment of defects in power plant components, both fossil and nuclear, is the knowledge of the crack driving force (K1, J, or C*). While the determination of the crack driving force is possible using finite element analyses, crack growth analyses using finite element methods can be expensive. Based on work by Il’yushin, it has been shown that for a power law hardening material, the fully plastic portion of the J-integral (or the C*-integral) is directly related to an h1 calibration function. The value of h1 is a function of the geometry and hardening exponent. The finite element program ABAQUS was used to evaluate the fully plastic J-integral and determine the h1 functions for various geometries. The Ramberg-Osgood deformation theory plasticity model, which may be used with the J-integral evaluation capability, allows the evaluation of fully plastic J solutions. Once it was established that the grid used to generate the h1 functions was adequate (based on the more recent work of Shih and Goan), additional runs were made of other configurations given in the EPRI Elastic-Plastic Fracture Handbook. Differences as great as 55 percent were found when compared to results given in the Handbook (single-edge crack plate under tension and plane stress with a/b = 0.5). Effects of errors in h1 on predicted failure load and creep crack growth are discussed.

Elastic-Plastic Analyses of Surface Flaws in a Reactor Vessel

1984 ◽  
Vol 106 (3) ◽  
pp. 247-254 ◽  
Author(s):  
W. W. Wilkening ◽  
H. G. deLorenzi ◽  
M. Barishpolsky
Keyword(s):  
Internal Pressure ◽  
Crack Front ◽  
Driving Force ◽  
Maximum Depth ◽  
Crack Driving Force ◽  
Elastic Plastic ◽  
Single Curve ◽  
Surface Flaws ◽  
Virtual Crack Extension Method ◽  
Design Pressure

Elastic-plastic analyses have been performed for the ASME Maximum Postulated Flaw and for three other semielliptical surface flaws in the beltline region of a nuclear reactor pressure vessel, with internal radius to thickness ratio, R/t, equal to 10, using nonlinear 3-D finite element methods based upon the deformation theory of plasticity. Three of the flaws had a maximum depth, a, equal to t/4, with aspect ratios, 2c/a, equal to 6 (the ASME Maximum Postulated Flaw), 4 and 3, respectively, where 2c is the surface length of the flaw. These flaws were analyzed for internal pressure varying from one to three times the design pressure, which is well into the fully plastic regime for the uncracked vessel. The fourth flaw had an aspect ratio, 2c/a, equal to 6, and its maximum depth, a, was equal to 3t/4. This deep flaw was analyzed for internal pressure varying from 60 percent of design pressure to twice the design pressure. The crack driving force was calculated as the energy release rate, J, using the virtual crack extension method. The results illustrate that, at the design pressure, plasticity near the crack front is so limited for the three flaws with a/t = 1/4 that an elastic analysis is adequate. At higher pressures, however, the elastic analyses become increasingly nonconservative and would grossly underestimate the severity of the flaws. The variation of both J and crack opening displacement, COD, along the crack front were studied. Generally, the values at the maximum depth location, denoted J* and COD*, respectively, were the maximum values, with minimum values occurring at the free surface. A simple normalization scheme was found which collapsed the J* versus pressure results for the four semielliptical flaws into a single curve. A similar normalization also collapsed the COD* versus pressure results for the four flaws into a single curve. In addition, a unique linear relationship between J* and COD* was found to apply for the results from all four sets of analyses for internal pressure levels up to at least 2.5 times the design pressure. The analyses therefore demonstrate that J and COD are equivalent measures of the crack driving force, and further demonstrate that a realistic 3-D elastic-plastic analysis is needed to properly assess the severity of surface flaws.

The Influence of Residual Stresses on Small Through-Clad Cracks in Pressure Vessels

1984 ◽  
Vol 106 (4) ◽  
pp. 383-390 ◽  
Author(s):  
H. G. deLorenzi ◽  
B. I. Schumacher
Keyword(s):  
Residual Stresses ◽  
Pressure Vessel ◽  
Driving Force ◽  
Base Material ◽  
Pressure Vessels ◽  
Plastic Behavior ◽  
Material Interface ◽  
Crack Driving Force ◽  
Elastic Plastic ◽  
Stress Relieving

The influence of cladding residual stresses on the crack driving force for shallow cracks in the wall of a nuclear pressure vessel is investigated. Thermo-elastic-plastic analyses were carried out on long axial through-clad and sub-clad flaws on the inside of the vessel. The depth of the flaws were one and three times the cladding thickness, respectively. An analysis of a semielliptical axial through-clad flaw was also performed. It was assumed that the residual stresses arise due to the difference in the thermal expansion between the cladding and the base material during the cool down from stress relieving temperature to room temperature and due to the subsequent proof test before the vessel is put into service. The variation of the crack tip opening displacement during these loadings and during a subsequent thermal shock on the inside wall is described. The analyses for the long axial flaws suggest that the crack driving force is smaller for this type of flaw if the residual stresses in the cladding are taken into account than if one assumes that the cladding has no residual stresses. However, the analysis of the semielliptical flaw shows significantly different results. Here the crack driving force is higher than when the residual stresses are not taken into account and is maximum in the cladding at or near the clad/base material interface. This suggests that the crack would propagate along the clad/base material interface before it would penetrate deeper into the wall. The elastic-plastic behavior found in the analyses show that the cladding and the residual stresses in the cladding should be taken into acocunt when evaluating the severity of shallow surface cracks on the inside of a nuclear pressure vessel.

The Configurational Force Concept in Elastic-Plastic Fracture Mechanics−Instructive Examples

2009 ◽  
Vol 417-418 ◽  
pp. 297-300 ◽  
Author(s):  
R. Schöngrundner ◽  
Otmar Kolednik ◽  
Franz Dieter Fischer
Keyword(s):  
Driving Force ◽  
Plastic Material ◽  
Shielding Effect ◽  
Integral Approach ◽  
J Integral ◽  
Configurational Force ◽  
Crack Driving Force ◽  
Elastic Plastic ◽  
Elastic Plastic Material ◽  
Elastic Plastic Materials

This paper deals with the determination of the crack driving force in elastic-plastic materials and its correlation with the J-Integral approach. In a real elastic-plastic material, the conventional J-integral cannot describe the crack driving force. This problem has been solved in Simha et al. [1], where the configurational force approach was used to evaluate in a new way the J-integral under incremental plasticity conditions. The crack driving force in a homogeneous elastic-plastic material, Jtip, is given by the sum of the nominally applied far-field crack driving force, Jfar, and the plasticity influence term, Cp, which accounts for the shielding or anti-shielding effect of plasticity. In this study, the incremental plasticity J-integral and the crack driving force are considered for a stationary and a growing crack.

A Unified Fatigue Life Calculation Model for Notched Components Based on Elastic-Plastic Fracture Mechanics

2007 ◽  
Vol 348-349 ◽  
pp. 525-528 ◽  
Author(s):  
G. Savaidis ◽  
A. Savaidis ◽  
O. Hertel ◽  
M. Vormwald
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Driving Force ◽  
Calculation Model ◽  
J Integral ◽  
Initial Model ◽  
Crack Driving Force ◽  
Elastic Plastic ◽  
Notched Specimens ◽  
Notched Components

Based on Dankert’s et al. [1] initial model for the elastic-plastic evaluation of fatigue crack growth in sheets providing elliptical notches, a generalized procedure enabling an improved evaluation of the effective ranges of the crack driving force (i.e. the J-Integral) as well as the application to arbitrary notched components has been developed [2]. The present paper presents the basic topics of the calculation model as well as its verification using experimental results from notched specimens with various notch shapes subjected to cyclic loading with various load ratios.

scholarly journals A Combined Experimental and Modelling Approach to Elastic–Plastic Crack Driving Force Calculation in the Presence of Residual Stresses

2016 ◽  
Vol 56 (8) ◽  
pp. 1313-1325 ◽  
Author(s):  
H. E. Coules ◽  
D. J. Smith ◽  
P. J. Orrock ◽  
K. Abburi Venkata ◽  
T. Pirling
Keyword(s):  
Residual Stresses ◽  
Driving Force ◽  
Crack Driving Force ◽  
Elastic Plastic ◽  
Force Calculation ◽  
Modelling Approach
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