Estimating J-R Curve From CVN Upper Shelf Energy and its Application

2016 ◽  
Author(s):  
Samarth Tandon ◽  
Ming Gao ◽  
Ravi Krishnamurthy ◽  
Richard Kania ◽  
Gabriela Rosca
Keyword(s):  
Fracture Resistance ◽  
Theoretical Background ◽  
Shelf Energy ◽  
Ductile Tearing ◽  
Failure Pressure ◽  
Tearing Instability ◽  
Integrity Management ◽  
Level 3 ◽  
Resistance Curves ◽  
Crack Resistance Curves

Accuracy in predictions of burst pressures for cracks in pipelines has significant impact on the pipeline integrity management decisions. One of the fracture mechanics models used for failure pressure prediction is API 579 Level 3 FAD ductile tearing instability analysis that requires J-R curves, i.e., crack resistance curves, for the assessment. However, J-R curves are usually unavailable for most pipelines. To overcome this technical barrier, efforts have been made to estimate the J-R curve indirectly from commonly available toughness data, such as the Charpy V-notched Impact Energy CVN values, by correlating the upper-shelf CVN value (energy) to the ductile fracture resistance J-R curve. In this paper, the theoretical background and studies made by various researchers on this topic are reviewed. Attempts made by the present study to establish correlations between CVN and J-R curves for linepipe materials are then presented. Application of this CVN-JR correlation to API 579 Level 3 FAD tearing instability assessment for failure pressure predictions is demonstrated with examples. The accuracy of the correlation is analyzed and reported.

Failure assessment diagrams. II. The use of single failure assessment lines

1994 ◽  
Vol 444 (1922) ◽  
pp. 483-496 ◽  
Keyword(s):  
Crack Growth ◽  
Deformation Theory ◽  
Curve Analysis ◽  
Alternative Proof ◽  
Crack Driving Force ◽  
Ductile Tearing ◽  
Natural Mapping ◽  
Tearing Instability ◽  
Failure Assessment ◽  
Level 3

In a previous paper a natural mapping was noted from the ( a, J ep ) diagram of R-curve analysis into the ( L r , K r ) failure assessment diagram (FAD) of the R6-revision 3 procedure. Assuming that J ep is obtained by a deformation theory of plasticity, the analytical expression for this mapping is given and used to derive the images in the FAD of the applied J ep curves and of the R-curve. If this mapping is sufficiently smooth, it may be used to provide an alternative proof that the critical R6-revision 3 load locus touches the R-curve image (RCI) when the crack extension and the load are the same as those predicted by R-curve analysis. The natural mapping may not always be 1:1 and this is illustrated by considering the example of a family of linear R-curves. The relations between the various other functions used in the FAD and R-curve analysis are studied analytically. In particular it is shown how to derive from any single failure assessment line (FAL) on which the assessment point is assumed to move during crack growth, either the implied R-curve (IRC) or, alternatively, the implied applied J ep curve (IAJC). Further comments are made on the internal consistency or conservatism of analyses of ductile tearing instability which use a single FAL on which the assessment point is assumed to move during crack growth, such as those characteristic of level 3 of PD6493 and options 1 and 2 of R6-revision 3. The method for testing the consistency or conservatism of an FAD with a single FAL which involves the calculation of the IAJC requires that the function J ep = j ep ( a, L ) of the structure be known for a specific restricted range of a and L only. In contrast, the deduction of the IRC requires a knowledge of the j ep ( a, L ) over a wider domain. It is emphasized that the assessment of conservatism throughout is not absolute but only relative to the predictions of R-curve analysis. As in the previous paper, the discussion is given in terms of the J based parameters. But the conclusions hold equally well for an FAD based on any other parameters describing crack driving force and crack resistance.

Limit Strains of X70 Pipes With a Semi-Elliptical Crack Based on Initiation and Ductile Tearing Criteria

2018 ◽  
Author(s):  
Ju-Yeon Kang ◽  
Youn-Young Jang ◽  
Nam-Su Huh ◽  
Ki-Seok Kim ◽  
Woo-Yeon Cho
Keyword(s):  
Crack Initiation ◽  
Crack Resistance ◽  
Crack Growth ◽  
Driving Force ◽  
J Integral ◽  
Resistance Curve ◽  
Crack Driving Force ◽  
Ductile Tearing ◽  
Resistance Curves ◽  
Crack Resistance Curves

Crack-tip opening displacement (CTOD) and J-integral have been used for elastic-plastic fracture parameters as a crack driving force (CDF) and crack resistance curve to evaluate tensile strain capacity (TSC) of cracked pipelines based on strain-based design (SBD). The TSC can be determined by using two kinds of failure criteria. One is based on the limit state corresponding to an onset of stable crack growth and the other is tangency approach which determines an onset of unstable crack growth by comparing crack driving force and resistance curve. For this reason, the accurate calculation of crack driving force and crack resistance curve is highly required to determine TSC. In the present study, the TSCs for X70 pipelines with a circumferential semi-elliptical surface crack were estimated based on both crack initiation and ductile tearing criteria using crack driving force diagram (CDFD) method. The CDF curves of cracked pipelines were calculated through the detailed elastic-plastic finite element (FE) analyses. Crack resistance curves were obtained from experimental data of single edged notch tension (SENT) specimens. Both the CDF and crack resistance curves were represented using CTOD and J-integral, respectively. As for loading conditions, axial strain and internal pressure were considered. The TSCs based on CTOD were compared with those based on J-integral to investigate the effect of choice of the fracture parameters on TSC. From the FE results, the TSCs based on ductile tearing allowed higher TSCs than those based on crack initiation. Although there were some differences between the TSCs using CTOD and J-integral, the effect of choice of fracture parameter on TSC with internal pressure was not significant.

On the Correlation of Crack Resistance Curves on Upper Shelf Energy for German RPV Steels

2007 ◽  
Author(s):  
Dieter Siegele ◽  
Jo¨rg Hohe ◽  
Gerhard Nagel
Keyword(s):  
Crack Resistance ◽  
Material Model ◽  
Transition Curve ◽  
Good Representation ◽  
Shelf Energy ◽  
Mean Values ◽  
Surveillance Programs ◽  
Fracture Appearance ◽  
Resistance Curves ◽  
Crack Resistance Curves

J-crack resistance (J-R) curves, numerically determined and based on correlation formulas with the upper shelf energy level (USE) of the Charpy transition curve have been compared with measured J-R curves for German RPV steels, determined from single specimen tests. The USE were determined as mean values of the results above 95% ductile fracture appearance, as available from usual application in irradiation surveillance programs and averaging the temperature effect. The J-R curves numerically determined by the Gurson material model give a good representation of the measured crack resistance curves and the application of the correlation with USE in U.S. NRC Regulatory Guide 1.161 results in enveloping approximations with conservativeness increasing with crack growth.

Comparison of Dynamic Tear and Charpy-V-Notch Impact Properties of Plate Steels

1978 ◽  
Vol 100 (2) ◽  
pp. 204-211 ◽  
Author(s):  
A. D. Wilson
Keyword(s):  
Quality Control ◽  
Carbon Steel ◽  
Fracture Resistance ◽  
Impact Test ◽  
Energy Transition ◽  
Steel Plates ◽  
Shelf Energy ◽  
Statistical Correlations ◽  
Fracture Appearance ◽  
Steel Grades

The increasing interest in the Dynamic Tear (DT) test for use in measuring the fracture resistance of steels in both quality control and research testing, invites a comparison to the commonly used Charpy-V-notch (CVN) impact test. The DT and CVN properties of 57 steel plates of various grades are compared in this survey. The investigation covered ASTM carbon steel grades A-36, A516, A537; ASTM alloy steel grades A533-B, AB42, A43; and other steels such as HY-130, ABS-E, and a C-Mn-Cb type. Graphical and statistical correlations were established between various DT and CVN properties including upper shelf energy, fracture appearance and mid-energy transition temperatures. These features were then compared to the nil ductility temperature (NDT). Certain of the correlations appear useful enough to allow casual prediction of DT behavior from CVN testing.

Experimental Investigation of Ductile Tearing Properties for API X70 and X80 Pipeline Steels

2005 ◽  
Author(s):  
Mauri´cio Carvalho Silva ◽  
Eduardo Hippert ◽  
Claudio Ruggieri
Keyword(s):  
Pipeline Steel ◽  
Standard Procedure ◽  
Tensile Tests ◽  
Compact Tension ◽  
Propagation Path ◽  
Pipeline Steels ◽  
Ductile Tearing ◽  
Resistance Curves ◽  
Unloading Compliance ◽  
Fracture Specimens

This work presents an investigation of the ductile tearing properties for API 5L X70 and X80 pipeline steels using experimentally measured crack growth resistance curves (J-R curves). Testing of the pipeline steels employed compact tension (C(T)) fracture specimens to determine the J-R curves based upon the unloading compliance method using a single specimen technique in accordance with the ASTM E1820 standard procedure. Conventional tensile tests and Charpy V-Notch tests were also performed to determine the mechanical and impact properties for the tested materials. Severe splitting running parallel with the crack propagation path with varied lengths was observed in all tested fracture specimens, particularly for the API X80 material. The occurrence of splits makes the determination of JIc and resistance curves more difficult, as delamination of interfaces positioned normal to the crack front decreases the effective thickness of the test piece, inducing plane stress conditions deep inside the specimen. This experimental characterization provides additional toughness and mechanical data against which the general behavior of X70 and X80 class pipeline steel can be compared.

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