Fracture Toughness of X100 Pipe Girth Welds Using SE(T) and SE(B) Tests

2012 ◽  
Author(s):  
Dong-Yeob Park ◽  
William R. Tyson ◽  
James A. Gianetto ◽  
Guowu Shen ◽  
Robert S. Eagleson
Keyword(s):  
Crack Length ◽  
Initial Crack ◽  
Opening Angle ◽  
Single Edge ◽  
Double Pass ◽  
Crack Propagation Resistance ◽  
Loading Mode ◽  
Post Test ◽  
Girth Welds ◽  
Tearing Resistance

Extensive single-edge notched tension (SE(T)) and single-edge notched bend (SE(B)) tests were performed to apply the SE(T) procedure developed at CANMET and the standard SE(B) procedure of ASTM E1820 to pipeline girth welds as a contribution to a broader project on strain-based design (SBD) for pipeline girth weld integrity. Specimens were precracked from the pipe inner surface to target lengths of 3 and 6 mm to represent surface-breaking weld flaws of single- and double-pass height, respectively. It was found that resistance curves for weld metal (WM) were much lower than those for base metal (BM) or heat affected zone (HAZ) specimens even though the WM strength overmatched the BM, owing to effects from the WM microstructure. The small crack-tip opening angle observed in post-test WM specimens was consistent with the low crack propagation resistance, which in turn results in small tearing resistance, TR. In general, toughness decreases with increase in initial crack length. J values and tearing resistance are found to be influenced by loading mode; toughness is higher in tension, SE(T), than in bending, SE(B) for a given crack length and test temperature.

Examination of the mode I critical stress intensity factor of wood obtained by single-edge-notched bending test

Holzforschung ◽  
2010 ◽  
Vol 64 (4) ◽  
Author(s):  
Hiroshi Yoshihara
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Length ◽  
Critical Stress ◽  
Initial Crack ◽  
Critical Stress Intensity Factor ◽  
Bending Test ◽  
Mode I ◽  
Single Edge

Abstract The critical stress intensity factor of mode I (K Ic) obtained by single-edge-notched bending (SENB) tests of wood was experimentally and numerically analyzed. A double cantilever beam (DCB) test was also conducted and the results were compared with those of SENB tests. The K Ic value was obtained by introducing an additional crack length into the equations used for analyzing the SENB test of isotropic material when the initial crack length ranged from 0.1 to 0.6 times the depth of the specimen.

An Experimental Study on J(CTOD)-R Curves of Single Edge Tension Specimens for X80 Steel

2012 ◽  
Author(s):  
Enyang Wang ◽  
Wenxing Zhou ◽  
Guowu Shen ◽  
Daming Duan
Keyword(s):  
Crack Length ◽  
Crack Tip ◽  
Initial Crack ◽  
Single Edge ◽  
X80 Steel ◽  
Toughness Testing ◽  
Unloading Compliance ◽  
Crack Tip Constraint ◽  
The Impact ◽  
Edge Tension

Fracture toughness testing of SE(T) and SE(B) specimens is carried out to experimentally develop J(CTOD)-R curves for the X80 steel based on the unloading compliance method. Six clamped (two shallow-cracked side-grooved, two deep-cracked side-grooved, and two deep-cracked plain-sided) SE(T) and two shallow-cracked side-grooved SE(B) specimens are tested. The impact of crack length on the J(CTOD)-R curves of the SE(T) specimens is investigated. The J(CTOD)-R curves of the shallow-cracked SE(T) specimens are significantly higher than those of the deep-cracked SE(T) specimens once the crack extension exceeds 0.5 mm. A comparison of the J(CTOD)-R curves associated with the SE(B) and SE(T) specimens suggests that the crack tip constraint for the SE(T) specimens is lower than that of the SE(B) specimens with the same nominal initial crack length, and that shallow-cracked SE(T) specimens have less constraint at the crack tip than deep-cracked SE(T) specimens.

Prediction of the Initial Crack Tip Microstructure in a Single Crystal of CuAlNi

1999 ◽  
Author(s):  
Galyna M. Vasko ◽  
Perry H. Leo ◽  
Thomas W. Shield
Keyword(s):  
Stress Field ◽  
Single Crystal ◽  
Crack Opening ◽  
Crack Tip ◽  
Initial Crack ◽  
Single Edge ◽  
Opening Displacement ◽  
Elastic Crack ◽  
Maximum Work ◽  
Anisotropic Elastic

Abstract The austenite to martensite pseudoelastic transformation induced by the anisotropic elastic crack tip stress field in a single crystal of shape memory alloy is considered. It is proposed that the orientation of the initial austenite-martensite interface that forms can be predicted based on knowledge of the stress field, the crystallography of the transformation and one of two selection criteria. These criteria are based on the work of formation of the martensite in stress field and the crack opening displacement the martensite causes at the crack. Predictions of the criteria are compared to experiments on three single edge notched CuAlNi single crystal specimens. Results indicate that the maximum work criterion accurately predicts the orientation of the austenite-martensite interfaces that initially form near a crack.

Flow Behaviour and Ductile Fracture Toughness of a High Toughness Steel

2004 ◽  
Author(s):  
S. Xu ◽  
R. Bouchard ◽  
W. R. Tyson
Keyword(s):  
Flow Stress ◽  
Ductile Fracture ◽  
Tensile Tests ◽  
Test Method ◽  
Opening Angle ◽  
Absorbed Energy ◽  
Crack Propagation Resistance ◽  
High Toughness ◽  
Drop Weight ◽  
Drop Weight Tear Test

This paper reports results of tests on flow and ductile fracture of a very high toughness steel with Charpy V-notch absorbed energy (CVN energy) at room temperature of 471 J. The microstructure of the steel is bainite/ferrite and its strength is equivalent to X80 grade. The flow stress was determined using tensile tests at temperatures between 150°C and −147°C and strain rates of 0.00075, 0.02 and 1 s−1, and was fitted to a proposed constitutive equation. Charpy tests were carried out at an initial impact velocity of 5.1 ms−1 using drop-weight machines (maximum capacity of 842 J and 4029 J). The samples were not broken during the test, i.e. they passed through the anvils after significant bending deformation with only limited crack growth. Most of the absorbed energy was due to deformation. There was little effect of excess energy on absorbed energy up to 80% of machine capacity (i.e. the validity limit of ASTM E 23). As an alternative to the CVN energy, the crack tip opening angle (CTOA) measured using the drop-weight tear test (DWTT) has been proposed as a material parameter to characterize crack propagation resistance. Preliminary work on evaluating CTOA using the two-specimen CTOA test method is presented. The initiation energy is eliminated by using statically precracked test specimens. Account is taken of the geometry change of the specimens (e.g. thickening under the hammer) on the rotation factor and of the effect of strain rate on flow stress.

scholarly journals Influence of static strength on the fatigue resistance of welds

2018 ◽  
Vol 165 ◽  
pp. 13010 ◽  
Author(s):  
Ceferino Steimbreger ◽  
Nenad Gubeljak ◽  
Norbert Enzinger ◽  
Wolfgang Ernst ◽  
Mirco Chapetti
Keyword(s):  
Crack Length ◽  
Driving Force ◽  
Base Material ◽  
Initial Crack ◽  
Static Strength ◽  
Resistance Curve ◽  
Weld Geometry ◽  
Curve Method ◽  
Mechanic Approach ◽  
Local Properties

The present paper deals with a fracture mechanic approach that employs the Resistance-Curve concept, in order to predict fatigue endurances of welded components, with different tensile strengths of the base metal. The Resistance-Curve method compares the total driving force applied to a crack with its threshold for propagation, both defined as a function of crack length. The former depends on load scheme and weld geometry and it can be obtained from finite element analyses, while the second is inherently related to weld resistance. Results obtained herein showed that threshold curve shape is changed when static strength of the base material is modified. Consequently, its interaction with the driving force differed, giving raise to different fatigue endurances for various values of the tensile strength. However, this effect is only likely to be leveraged, provided that the initial crack length is small enough. In real welded structures, the presence of defects demands longer initial crack lengths to be used in calculations, at which the benefit of enhanced strength is minimised or even inverted. Moreover, at these lengths, the growing process is mainly controlled by weld geometry and long crack propagation threshold, whereas local properties become less important in fatigue limit prediction.

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.

The Critical Load Measurements of Pineapple Leaf Fibre Reinforced Polyester Composite Using Single Edge Notched Beam (SENB) Testing

2016 ◽  
Vol 1 ◽  
Author(s):  
Hendery Dahlan
Keyword(s):  
Composite Material ◽  
Crack Propagation ◽  
Critical Load ◽  
Fibre Orientation ◽  
Initial Crack ◽  
Single Edge ◽  
Main Attention ◽  
Good Resistance ◽  
Tensile Impact ◽  
Polyester Composite

<h1><strong>Pineapple leaf fibre has potential as reinforcement in composite material due to their advantages such as renewable fibre and abundantly available. Some studies have been conducted relating to their mechanical properties using tensile, impact and bending testing. However the analysis of crack propagation in pineapple leaf fibre reinforced polyester composite is still limited. In this paper, the main attention is therefore the critical load leading to crack propagation in the composite material for two different fibre orientations. The crack propagation is investigated using single edge notched beam (SENB) testing. The composite material was manufactured by hand lay-up with two different nonwoven fibre orientations i.e. 0o/90oand +45o/-45o. Then, five different initial crack lengths are given in experimental specimen. The result reveals that increasing initial crack length will decrease the value of critical load for both fibre orientations. Furthermore, the fibre orientation influences the critical loading. In general the critical load leading to crack propagation for composite with +45o/-45o orientation has higher value than composite with 0o/90o orientation. It can be concluded that the composite material with +45o/-45o orientation has good resistance to the crack growth.<br /></strong></h1>

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