Integrity of Longitudinal Welds in Pipelines: Bridging Scales

2018 ◽  
Author(s):  
Marion Erdelen-Peppler ◽  
Christoph Kalwa ◽  
Jens Schröder
Keyword(s):  
Circumferential Stress ◽  
Ring Expansion ◽  
Structural Behavior ◽  
Single Edge ◽  
Crack Tip Opening Displacement ◽  
Single Edge Notch ◽  
Wide Range ◽  
Edge Notch ◽  
Longitudinal Welds ◽  
The Impact

Toughness testing of the heat affected zone (HAZ) of longitudinal welds is increasingly often required in pipeline standards and specifications. This includes simple tests such as the Charpy impact test that was designed to serve as quality test as well as enhanced methods including crack tip opening displacement (CTOD) tests that are necessary to conduct an engineering critical assessment (ECA). If occasional low toughness values are observed, the question turns towards assessing the impact of such numbers and how representative they are of the behavior of a pipe in service. The significance of low toughness values measured in laboratory testing can be judged on basis of ring expansion and hydraulic burst tests. The current study summarises an extensive test series to quantify the toughness of submerged arc welds (SAW) obtained by different test methods. The tested pipes cover a wide range of material including medium strength X70 up to high strength X100. Their welds are characterized in terms of fracture toughness properties with single edge notch tension (SENT) and single edge notch bending (SENB) tests. Different constraint levels are obtained within each series by introducing notches of standard depth as well as shallow notches. Structural behavior is characterized with burst tests as well as ring expansion tests containing notches in the longitudinal weld. The experimental results are assessed within dedicated finite element studies. The assessment is conducted for pipes serving as pressure containment, thus having circumferential stress resulting from internal pressure. Based on the results achieved the conclusion can be drawn that the standard route including high constraint CTOD leads to overly conservative results concerning the integrity of longitudinal welds. A better representation of structural behavior is observed in ring expansion tests.

Wide Range Compliance Solutions for Various Fracture Test Specimens Using Crack Mouth Opening Displacement

2017 ◽  
Author(s):  
Claudio Ruggieri ◽  
Rodolfo F. de Souza
Keyword(s):  
Mouth Opening ◽  
Crack Mouth Opening Displacement ◽  
Width Ratio ◽  
Fracture Test ◽  
Single Edge ◽  
Opening Displacement ◽  
Element Analysis ◽  
Single Edge Notch ◽  
Wide Range ◽  
Edge Notch

This work addresses the development of wide range compliance solutions for tensile-loaded and bend specimens based on CMOD. The study covers selected standard and non-standard fracture test specimens, including the compact tension C(T) configuration, the single edge notch tension SE(T) specimen with fixed-grip loading (clamped ends) and the single edge notch bend SE(B) geometry with varying specimen spam over width ratio and loaded under 3-point and 4-point flexural configuration. Very detailed elastic finite element analysis in 2-D setting are conducted on fracture models with varying crack sizes to generate the evolution of load with displacement for those configurations from which the dependence of specimen compliance on crack length, specimen geometry and loading mode is determined. The extensive numerical analyses conducted here provide a larger set of solutions upon which more accurate experimental evaluations of crack size changes in fracture toughness and fatigue crack growth testing can be made.

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.

scholarly journals Post Impact Tensile and Single Edge Notch Bending Test of Kenaf Hybrid Composite

2019 ◽  
Vol 9 (1) ◽  
pp. 5657-5662
Keyword(s):  
Tensile Test ◽  
Hybrid Composites ◽  
Testing Machine ◽  
Bending Test ◽  
Single Edge ◽  
Single Edge Notch ◽  
Wide Range ◽  
Edge Notch ◽  
Post Impact ◽  
Single Edge Notch Bend

The improvement of elite building items produced using regular assets is expanding around the world due to renewable and ecological issues. Among the wide range of characteristic assets, kenaf plants have been broadly abused in the course of recent years. The aim of this research is to develop long kenaf composites and long kenaf with woven glass reinforced polyester resin composites. Tensile test helps to determine how the material will react to forces being applied in tension. The test that was conducted included Post Impact Tensile test and Single Edge Notch Bend. Tensile test determines strain-stress while single edge notch bend determines the fracture of the specimen. The experiment was conducted using Universal Testing Machine (UTM) to find the mechanical properties. The experiment considered ASTM D3039 for tensile test and ASTM D5045 for single edge notch bending. From there, the damage area of the composites could be predicted. Meanwhile, it showed the best configuration for the newly developed material in impact test. So, these hybrid composites are viable to be extended into a newly developed material for further investigation

scholarly journals RESPONSE AND DAMAGE EVOLUTION OF SINGLE EDGE NOTCHED TIMBER BEAMS UNDER THREE-POINT BENDING

2020 ◽  
Vol 26 ◽  
pp. 94-99
Author(s):  
Eliška Šmídová ◽  
Petr Kabele ◽  
Michal Šejnoha
Keyword(s):  
Damage Evolution ◽  
Image Correlation ◽  
Single Edge ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Three Point Bending ◽  
Single Edge Notch ◽  
Failure Patterns ◽  
Edge Notch ◽  
Timber Beams

Two groups of small-size single edge notched beams (SENB) made of European spruce (Picea abies) were tested in three-point bending (3PB) until failure under displacement control. The first group comprised of eight solid and two glued laminated (GL) timber beams manufactured with (a) the single edge notch at the bottom of the mid-span and (b) the reduced ligament depth. The second group consisted of four GL timber beams with the single edge notch only. We employed digital image correlation (DIC) to quantify strains and displacements, capture the damage evolution, and track the sequence of failure patterns. In this work, we present response of the beams in terms of load vs. crosshead displacement of the moving crosshead and load vs. crack tip opening displacement (CTOD).

scholarly journals Modelling the Variability and the Anisotropic Behaviour of Crack Growth in SLM Ti-6Al-4V

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1400
Author(s):  
Rhys Jones ◽  
Calvin Rans ◽  
Athanasios P. Iliopoulos ◽  
John G. Michopoulos ◽  
Nam Phan ◽  
...  
Keyword(s):  
Crack Growth ◽  
The United States ◽  
Fatigue Threshold ◽  
Growth Equation ◽  
Single Edge ◽  
Test Program ◽  
Large Variability ◽  
Single Edge Notch ◽  
Anisotropic Behaviour ◽  
Edge Notch

The United States Air Force (USAF) Guidelines for the Durability and Damage Tolerance (DADT) certification of Additive Manufactured (AM) parts states that the most difficult challenge for the certification of an AM part is to establish an accurate prediction of its DADT. How to address this challenge is the focus of the present paper. To this end this paper examines the variability in crack growth in tests on additively manufactured (AM) Ti-6Al-4V specimens built using selective layer melting (SLM). One series of tests analysed involves thirty single edge notch tension specimens with five build orientations and two different post heat treatments. The other test program analysed involved ASTM standard single edge notch specimens with three different build directions. The results of this study highlight the ability of the Hartman–Schijve crack growth equation to capture the variability and the anisotropic behaviour of crack growth in SLM Ti-6Al-4V. It is thus shown that, despite the large variability in crack growth, the intrinsic crack growth equation remains unchanged and that the variability and the anisotropic nature of crack growth in this test program is captured by allowing for changes in both the fatigue threshold and the cyclic fracture toughness.

Stress concentration of a strip with a single edge notch

1987 ◽  
Vol 28 (2) ◽  
pp. 223-238 ◽  
Author(s):  
Noda Nao-Aki ◽  
Nisitani Hironobu
Keyword(s):  
Stress Concentration ◽  
Single Edge ◽  
Single Edge Notch ◽  
Edge Notch
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