Transformation of BS7448-CTOD to ASTM E1290-CTOD

2008 ◽  
Author(s):  
Yoichi Kayamori ◽  
Takehiro Inoue ◽  
Tetsuya Tagawa
Keyword(s):  
Strain Hardening ◽  
Strain Hardening Exponent ◽  
Test Results ◽  
Single Edge ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Edge Notch ◽  
Crack Tip Opening ◽  
The Relationship ◽  
Single Edge Notch Bend

Experimental and analytical investigations into Crack Tip Opening Displacement, CTOD, were conducted to demonstrate the relationship between BS7448-CTOD and ASTM E1290-CTOD. CTOD test results showed that ASTM-CTOD was occasionally much lower than BS-CTOD both in single edge notch bend specimens and in CT specimens for low-strength structural steels, and this tends to be more remarkable in CT specimens. In addition, the analytical results of simplified elastic-plastic facture parameter calculation using the Electric Power Research Institute scheme demonstrated that the ratio of ASTM-CTOD to BS-CTOD was not constant but varied according to CTOD changes. Material factors such as the yield stress, the strain hardening exponent, specimen size and configurations influenced the CTOD ratio, and low strain hardening exponent in the Ramberg-Osgood relation and CT specimen configuration significantly decreased the CTOD ratio. An equation that transforms BS-CTOD into ASTM-CTOD is proposed in this study. This equation gives a good estimate of ASTM-CTOD from BS-CTOD.

Transformation of BS7448-CTOD to ASTM E1290-CTOD

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Yoichi Kayamori ◽  
Takehiro Inoue ◽  
Tetsuya Tagawa
Keyword(s):  
Strain Hardening ◽  
Compact Tension ◽  
Strain Hardening Exponent ◽  
Fracture Parameter ◽  
Test Results ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Edge Notch ◽  
Crack Tip Opening ◽  
The Relationship

Experimental and analytical investigations into crack tip opening displacement (CTOD) were conducted to demonstrate the relationship between BS7448-CTOD and ASTM E1290-CTOD. The CTOD test results showed that ASTM-CTOD was occasionally much lower than BS-CTOD both in single edge notch bend specimens and in compact tension (C(T)) specimens for low-strength structural steels, and this tended to be more remarkable in C(T) specimens. In addition, the analytical results of simplified elastic-plastic fracture parameter calculation using the Electric Power Research Institute scheme demonstrated that the ratio of ASTM-CTOD to BS-CTOD was not constant but varied according to CTOD changes. Material factors such as the yield stress, the strain hardening exponent, specimen size and configurations influenced the CTOD ratio, and low strain hardening exponents in the Ramberg–Osgood relation and C(T) specimen configuration significantly decreased the CTOD ratio. An equation that transforms BS-CTOD into ASTM-CTOD is proposed in this study. This equation gives a good estimate of ASTM-CTOD from BS-CTOD.

scholarly journals Numerical Analysis of the Influence of In-Plane Constraints on the Crack Tip Opening Displacement for SEN(B) Specimens Under Predominantly Plane Strain Conditions

2016 ◽  
Vol 21 (4) ◽  
pp. 849-866 ◽  
Author(s):  
M. Graba
Keyword(s):  
Numerical Analysis ◽  
Plane Strain ◽  
Crack Tip ◽  
Strain Hardening Exponent ◽  
Single Edge ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
New Formula ◽  
Crack Tip Opening ◽  
The Relationship

Abstract This paper presents a numerical analysis of the relationship between in-plane constraints and the crack tip opening displacement (CTOD) for single-edge notched bend (SEN(B)) specimens under predominantly plane strain conditions. It provides details of the numerical model and discusses the influence of external load and in-plane constraints on the CTOD. The work also reviews methods for determining the CTOD. The new formula proposed in this paper can be used to estimate the value of the coefficient dn as a function of the relative crack length, the strain hardening exponent and the yield strength - dn(n, σ0/E, a/W), with these parameters affecting the level of in-plane constraints. Some of the numerical results were approximated using simple mathematical formulae.

Plastic Rotational Factor Calculation for Shallow-Notched SE(B) Specimens

2014 ◽  
Vol 783-786 ◽  
pp. 2322-2326 ◽  
Author(s):  
Yoichi Kayamori ◽  
Takehiro Inoue ◽  
Yukito Hagihara
Keyword(s):  
Plastic Hinge ◽  
Single Edge ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Edge Notch ◽  
New Equation ◽  
Hinge Model ◽  
Testing Standards ◽  
Crack Tip Opening ◽  
Rotational Factor

The plastic part of crack tip opening displacement (CTOD) is derived from the plastic hinge model for deep-notched single edge-notch bend (SE(B)) specimens in BS, WES and ISO CTOD testing standards, and a typical plastic rotational factor is given by a constant value of 0.4. This value is appropriate for deep-notched SE(B) specimens, but is not suitable for shallow-notched SE(B) specimens. In this study, a new equation of calculating the plastic rotational factor was obtained by using the Electric Power Research Institute (EPRI) scheme. The equation shows the effect of crack length and strain hardening on the plastic rotational factor, and is useful for evaluating CTOD in shallow-notched SE(B) specimens.

Fracture Toughness Estimation for Pipeline Girth Welds

2002 ◽  
Author(s):  
Henryk G. Pisarski ◽  
Colin M. Wignall
Keyword(s):  
Fracture Toughness ◽  
Weld Metal ◽  
Specimen Geometry ◽  
Single Edge ◽  
Single Edge Notch ◽  
Edge Notch ◽  
Loading Modes ◽  
Girth Welds ◽  
The Relationship ◽  
Single Edge Notch Bend

The relationship between fracture toughness estimated using standard single edge notch bend (SENB), single edge notch tension (SENT) test specimens and fracture toughness associated with a circumferential flaw in a pipe girth weld is explored in terms of constraint using the Q parameter. It is shown that in the elastic-plastic regime, use of standard deeply notched SENB specimens provides a conservative assessment of fracture toughness, for both weld metal and HAZ, because of the high constraint associated with this specimen geometry. Use of specimen geometries and loading modes associated with lower constraint (e.g. SENT and shallowed notched SENB specimens), allow for improved estimates of fracture toughness to be made that are appropriate for the assessment of circumferential flaws in pipe girth welds. Recommendations are given on the specimen designs and notch orientations to be employed when evaluating weld metal and HAZ fracture toughness.

Fracture Toughness of X70 Pipe Girth Welds Using Clamped SE(T) and SE(B) Single-Specimens

2014 ◽  
Author(s):  
Dong-Yeob Park ◽  
Jean-Philippe Gravel ◽  
C. Hari Manoj Simha ◽  
Jie Liang ◽  
Da-Ming Duan
Keyword(s):  
Fracture Toughness ◽  
Heat Affected Zone ◽  
Peak Load ◽  
Single Specimen ◽  
Single Edge ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Resistance Curves ◽  
Girth Welds ◽  
Crack Tip Opening

Shallow-notched single edge-notched tension (SE(T) or SENT) and deep- and shallow-notched single edge-notched bend (SE(B) or SENB) specimens with notches positioned in the weld and the heat-affected zone were tested. Crack-tip opening displacement (CTOD) versus resistance curves were obtained using both a single and double clip gauge consolidated in a SE(T) single-specimen. Up until the peak load the resistance curves from both gauging methods yield approximately the same results; thereafter the curves deviate. Interrupted testing showed that the crack had initiated below 50% of the peak load, and in some cases had propagated significantly prior to reaching the peak load.

Prediction of Cleavage Fracture From Non-Sharp Defects Using the Weibull Stress Based Toughness Scaling Model

2009 ◽  
Author(s):  
Anthony J. Horn ◽  
Andrew H. Sherry
Keyword(s):  
Cleavage Fracture ◽  
Fracture Initiation ◽  
Test Results ◽  
Single Edge ◽  
Care Needs ◽  
Scaling Model ◽  
Numerical Predictions ◽  
Edge Notch ◽  
Weibull Stress ◽  
Single Edge Notch Bend

Non-sharp defects exhibit a higher resistance to cleavage fracture than sharp cracks. This study uses the Weibull stress based toughness scaling model to predict cleavage fracture initiation in Single Edge Notch Bend SE(B) specimens with notches of varying root radii. Numerical predictions are compared with the results of an experimental study of SE(B) specimens with similar notches. The predictions correlate well with the test results, indicating that the Weibull stress approach and toughness scaling model can be successfully applied to predict cleavage fracture initiation from non-sharp defects. However, care needs to be taken to ensure that calibration of the Weibull parameters references fracture toughness data from constraint levels that span the defect of interest. This ensures the model interpolates between the constraint states used for calibration, rather than extrapolating outside the range of applicability.

Comparison between Fracture Behaviour of Pipe-Line Ring Specimens and Standard Specimens

2013 ◽  
Vol 577-578 ◽  
pp. 637-640 ◽  
Author(s):  
Nenad Gubeljak ◽  
Andrej Likeb ◽  
Jožef Predan ◽  
Yu. G. Matvienko
Keyword(s):  
Fracture Behaviour ◽  
Strain Relaxation ◽  
Crack Tip ◽  
Fatigue Loading ◽  
Single Edge ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Single Edge Notch ◽  
Pipe Line ◽  
Edge Notch

Thethin walled structures as pipe-line are often unsuitable for standard testingof fracture toughness. One possibility is applying non-standard modifiedspecimens with simple testing procedure, but measured fracture behaviour isconsequence of loading conditions and geometry of specimen. In this paper thedifferences in fracture behaviour of single edge notch bending (SENB) and ringpipe-line bended specimens are discussed. Especially uneven fatigue crack frontas consequence of complex fatigue loading caused different fracture behaviour,than standard single edge notch bending (SENB) specimens. The stress-strainconditions at the crack tip are analysed by finite element modelling. Thecritical crack tip opening displacement has been determined as a crack tipsurface strain-relaxation by using stereo-optical grading method. Comparisonbetween CTOD-R curves of both types of specimens shows difference in crackdriving force.

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