3D stress intensity factors for weld toe semi-elliptical surface cracks using XFEM

Pang, J.H.L.; Tsang, Kin Shun; Hoh, Hsin Jen

doi:10.1016/j.marstruc.2016.04.001

Cited by 26 publications

(16 citation statements)

References 10 publications

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“…Fifth, the element size, especially for those around the surface crack tip, should be defined properly. For different model geometries, an investigation on the proper element size is necessary to guarantee the accuracy of SIFs evaluation and to save the computing time [50]. Last but not least, the interaction angle between the crack front and the free surface of the pipe should be carefully modelled in order to ensure the square singularity at the corner point [51].…”

Section: Fe Modelling Strategymentioning

confidence: 99%

Surface Crack Growth in Offshore Metallic Pipes under Cyclic Loads: A Literature Review

Jiang

Hopman

2020

JMSE

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The surface crack, also known as the partly through-thickness crack, is a serious threat to the structural integrity of offshore metallic pipes. In this paper, we review the research progress in regard to surface crack growth in metallic pipes subjected to cyclic loads from the fracture mechanics perspective. The purpose is to provide state-of-the-art investigations, as well as indicate the remaining challenges. First, the available studies on surface cracked metallic pipes are overviewed from experimental, numerical, and analytical perspectives, respectively. Then, we analyse state-of-the-art research and discuss the insufficiencies of the available literature from different perspectives, such as surface cracks and pipe configurations, environmental influential parameters, the girth welding effect, and numerical and analytical evaluation methods. Building on these surveys and discussions, we identify various remaining challenges and possible further research topics that are anticipated to be of significant value both for academics and practitioners.

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Section: Fe Modelling Strategymentioning

confidence: 99%

Surface Crack Growth in Offshore Metallic Pipes under Cyclic Loads: A Literature Review

Jiang

Hopman

2020

JMSE

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“…Pasca et al [9] determined the 3D stress intensity factors along the crack growth path of quarterelliptical corner cracks for T joint using FRANC3D in tension and bending loadings; crack growth paths were obtained from Paris' law based on the maximum tensile stress criterion. Pang et al [10] studied the 3D stress intensity factor and weld toe magnification factor of a semielliptical weld toe crack for T-butt joint using the three-dimensional extended finite element method. They investigated the modeling of fatigue crack growth of weld toe semielliptical surface cracks for initial surface cracks with crack depth to plate thickness ratio (a/T) of 0.01 and three different crack aspect ratios (a/c) of 0.25, 0.5, and 1.0.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the stress intensity factor of welded joints under prior corrosion and complex stress fields

Jie

Wei

2016

J. Mod. Transport.

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Taking cruciform welded joints under different corrosion degrees, together with 45°inclined angle and full penetration load-carrying fillet, as the research object, the stress intensity factor of a quarter-circular corner crack of welded joints is calculated based on FRANC3D with ABAQUS. Effects of different corrosion pit sizes, crack aspect ratios, and crack depths on stress intensity factor are analyzed. The results show that pit depth plays a major role in stress intensity factor, while the effect of pit radius is relatively small. The cracking modes of the surface and the deepest point are mode I, and mixed modes I and II, respectively. Effects of pit depths, crack aspect ratios, and crack depths on the stress intensity factor at the surface point are greater than at the deepest point.

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“…Many studies had been carried out to evaluate the fatigue strength based on SIF calculations of weld toe cracks [31,[80][81][82], but the SIF equations obtained are confined to 2-D configuration cases only. In practice, the crack at the weld toe is found to resemble a semi-elliptical in shape [64,83,84], and the SIF equations for this crack profile have not been established for loadcarrying cruciform fillet welded joints. Therefore, the main objective of this study is to propose a new set SIF equations for load-carrying cruciform fillet welded joints containing a semielliptical crack at the weld toe based on 3-D linear elastic FE analyses.…”

Section: Background Of Loading-carrying Cruciform Jointsmentioning

confidence: 99%

“…Linear elastic fracture mechanics (LEFM) is a common method to calculate the fatigue strength and predict the fatigue life based on the Paris' law [15], establishing the relationship between the crack growth rate and the applied stress intensity factor (SIF) range. The key of LEFM approach in fatigue assessment is the determination of SIF solutions for specific geometries [60,64,71,75,84,96,97]. Newman and Raju [60] proposed empirical equations for the SIFs of a surface crack in a plain plate under axial and bending loadings, respectively.…”

Section: Determination Of Critical Crack and Weld Sizesmentioning

confidence: 99%

“…Hence, the weld toe in the misaligned pipe is a more critical location of crack initiation and propagation in comparison with that in a plain pipe. It is worth noting that the aforementioned research works [60,64,74,84,[96][97][98][99] are all about fatigue and fracture analyses of aligned configurations with a surface crack at the weld toe. However, the SIF equations of a weld toe crack in misaligned pipes are not available.…”

Section: Determination Of Critical Crack and Weld Sizesmentioning

confidence: 99%

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Fracture assessment of cracked clad pipelines with weld misalignment

Zhao¹

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With increasing demand of recoverable corrosive hydrocarbons, metallurgically bonded double walled pipelines, referred to as clad pipelines, are widely used to transport the corrosive natural resources. The clad pipelines consist of a carbon steel outer pipe providing the load capacity and a corrosion resistant alloy liner protecting the carbon steel outer pipe from corrosion. The pipeline is constructed by joining one end of the pipe to the other end by girth welding process, and potential cracks are usually detected to initiate from the welding region. Furthermore, weld misalignment, centerline offset misalignment or angular misalignment, is also invariably introduced into the pipeline during the welding process, which further reduces the integrity of the pipes due to the introduction of local bending stress. Therefore, it's crucial to investigate the fracture responses of cracked clad pipelines with weld misalignment. Although BS7910-Amendment 1 [1] has proposed a fracture assessment equation for misaligned structures, the equation actually uses fracture parameters of aligned configurations to assess the corresponding parameters of misaligned ones based on superposition principle, resulting in an over-conservative prediction. Therefore, the fracture analysis for cracked configurations with weld misalignment needs to be investigated in detail. In this study, a finite element (FE) mesh generator is developed to serve for the cracked clad pipelines with weld misalignment, and a small-scale experimental test is carried out to verify the validity of the mesh generator. Based on the mesh generator, extensive 3-D FE analysis is performed to determine the stress intensity factors (SIFs) of aligned and misaligned welded joints. The corresponding SIF equations are proposed using multiple regression analysis, which consider the effect of weld misalignment on the SIFs directly, not by the superposition principle. Then, the fracture responses for oval-shaped clad pipelines with a surface crack are analyzed, and an equivalent J-estimation procedure is built up. Finally, engineering critical assessment is conducted to investigate the effect of weld misalignment on the cracked clad pipelines, and a fracture assessment framework covering the commonly used pipe configurations is established to predict the fracture parameters.

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3D stress intensity factors for weld toe semi-elliptical surface cracks using XFEM

Cited by 26 publications

References 10 publications

Surface Crack Growth in Offshore Metallic Pipes under Cyclic Loads: A Literature Review

Surface Crack Growth in Offshore Metallic Pipes under Cyclic Loads: A Literature Review

Analysis of the stress intensity factor of welded joints under prior corrosion and complex stress fields

Fracture assessment of cracked clad pipelines with weld misalignment

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