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  • 1
    Electronic Resource
    Electronic Resource
    Fatigue life prediction of offshore tubular joints using fracture mechanics (2002)
    Oxford, UK : Blackwell Science Ltd
    Fatigue & fracture of engineering materials & structures 25 (2002), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Fatigue crack growth calculations were performed on offshore tubular joints using the Paris crack growth law. The stress intensity factors required for such calculations were obtained from T-butt solutions previously proposed by the authors. The applicability of the solutions to tubular joints was first demonstrated by comparing the fatigue life of a base case with that obtained from a mean S–N curve, and the influence on fatigue life of various factors including load shedding, the size of initial defects, weld geometry, etc. was investigated. The solutions were then used to predict the lives of tubular T-joints from an experimental database. The results show that the solutions underestimate the fatigue life; this underestimation was shown to be primarily due to ignoring the combined effects of load shedding and the intersection stress distribution. In general, however, the trends in the predicted fatigue lives with joint geometry and other details were seen to be superior to predictions from the S–N approach, with the solutions significantly reducing the dependency on loading mode exhibited by the test data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-2695.2002.00566.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    J-INTEGRAL SOLUTIONS FOR SHALLOW CRACK GEOMETRIES UNDER COMBINED TENSION AND BENDING (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 19 (1996), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper presents J-integral solutions for geometries with shallow edge cracks (0.05 ≤a/W≤ 0.1) subjected to combined tension and bending. Tension and bending is applied simultaneously and sequentially. Curves of J versus structural strain are obtained from two-dimensional plane strain finite element analyses using medium to low work hardening power laws to represent material behaviour. Empirical equations are derived from the finite element results to estimate the J-integrals, using previously developed J-estimation schemes for SENT and SENB specimens with only minor modifications. The predictions presented are invariably safe, but due to the complexity of the problems studied and the variability of the loadings considered, the degree of conservatism is found to be high in some cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1996.tb00997.x
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  • 3
    Electronic Resource
    Electronic Resource
    STRESS INTENSITY FACTOR SOLUTIONS FOR SEMI-ELLIPTICAL WELD-TOE CRACKS IN T-BUTT GEOMETRIES (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 19 (1996), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract— Weld toe magnification factors are widely used in the evaluation of stress intensity factors for cracks in welded structures. Traditionally, the weld magnification factor has been determined from 2-D plane strain models containing edge cracks. However, it has long been recognised that a semi-elliptical weld toe crack cannot be accurately represented by a 2-D approximation due to the 3-D nature of the geometry. As a consequence, some recent research has been carried out using 3-D numerical modelling, which highlights the limitations of the 2-D approach. Nevertheless, 3-D solutions are still scarce and are of limited validity due to the difficulties associated with creating the numerical models. This paper reports the most extensive 3-D numerical investigation of semi-elliptical cracks in T-butt geometries to date. Based on the numerical results, new and accurate equations for weld magnification factors were derived, which quantify the 3-D effects present and emphasise the importance of the attachment. The results obtained from these equations are then used in an assessment of existing solutions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-2695.1996.tb01323.x
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  • 4
    Electronic Resource
    Electronic Resource
    J estimation for shallow semi-elliptical surface cracks in wide plates under pure bending (1999)
    Oxford, UK : Blackwell Science Ltd
    Fatigue & fracture of engineering materials & structures 22 (1999), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Three-dimensional finite element models have been used to predict the J versus applied strain behaviour of shallow semi-elliptical surface cracks in wide steel plates. These models were loaded in pure bending up to fully plastic conditions that produced maximum strains remote from the crack of 10 times the yield strain. This study examined cracks with a crack depth to plate thickness ratio (a/t) in the range 0.05–0.15, and crack depth to crack half-length ratio (a/c) from 0.2 to 0.57, in elastic-hardening materials as well as those with a yield plateau before strain-hardening. The results were found to differ significantly from those obtained from plane strain analyses, and a J estimation scheme was developed from the three-dimensional results. Comparisons between the results obtained in this work and the J predictions provided by existing defect assessment methods show that the proposed equations are a significant improvement when large strains are likely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-2695.1999.00170.x
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  • 5
    Electronic Resource
    Electronic Resource
    The development of an accurate model for the fatigue assessment of doubly curved cracks in tubular joints (1995)
    Springer
    International journal of fracture 73 (1995), S. 129-147 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Fatigue tests on tubular joints have shown that as a crack propagates through the chord wall, it curves under the weld toe. This produces, at the brace-chord intersection, a doubly curved semi-elliptical crack emanating from the weld toe. A doubly curved crack in a tubular joint is a very complex geometry which has proved to be difficult to model. In consequence, previous work on the evaluation of stress intensity factors in tubular joints adopted a simplified approach, ignoring the crack curvature under the weld toe. However, in the absence of benchmark solutions, the effects of any modelling approximation on accuracy are impossible to quantify. To address this problem and as part of the research on fatigue assessment methodologies, a technique which is able to accurately model doubly curved cracks in tubularT-joints has been developed at University of Wales, Swansea. This paper describes a detailed account of the generation of the finite element model and the procedure for evaluating the stress intensity factor solutions. The validation results are also presented to demonstrate the reliability of the model developed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00055725
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  • 6
    Electronic Resource
    Electronic Resource
    A numerical and experimental study on defect assessment of plain and welded bars with shallow crack geometries (1993)
    Springer
    International journal of fracture 62 (1993), S. 245-268 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Several fracture mechanics based models are currently available for defect assessment. These models generally assume that any defects present in the structure are located in materials of uniform properties and make no provision for the possible differences in deformation behaviour of components fabricated with dissimilar material. Extensive research using numerical simulation has been carried out for a number of years at University College of Swansea to investigate the effects of weld mismatch on potential fracture behaviour. However, no detailed validation work has been done to verify the large amount of data generated so far. The work presented in this paper was aimed at filling this gap. Crack tip parameters of single edge notch specimens under pure bending and direct tension were studied using a combination of experimental and numerical techniques. The results of this combined study confirm the validity and accuracy of the numerical procedure used. Comparison of the values of CTOD and J-integral with those obtained using the defect assessment models shows that these models are not adequate even for predicting behaviour of homogeneous specimens. Much research is therefore still required to develop procedures for accurate predictions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00012542
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  • 7
    Electronic Resource
    Electronic Resource
    J-integral estimation for single edge notch specimens in tension (1993)
    Springer
    International journal of fracture 63 (1993), S. 75-87 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A new J-integral estimation scheme for single edge notch specimens in tension (SENT) is presented. The scheme consists of equations obtained by analysing finite element results of SENT specimens under plane strain conditions, and separate equations have been derived for two forms of idealized material stress-strain curves-power law and bilinear representations. Non-dimensional J values are presented as functions of non-dimensional far field strains which eliminate the dependency of J on the aspect ratios of specimens. It was found that both the material law and the crack depth to specimen depth ratio had significant influences on the predicted J values and by presenting equations for different parts of the J versus strain curves, the scheme is able to take these influences into account.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00053317
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  • 8
    Electronic Resource
    Electronic Resource
    The sensitivity of J-integrals to material law variations for semi-elliptical surface cracks (1996)
    Springer
    International journal of fracture 80 (1996), S. 365-375 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In finite element analysis of cracked bodies, it is quite common to represent the material law (stress-strain curve) in a simplified form e.g. bilinear approximation. Many steels, however, have a more complex material law, which includes a perfectly plastic region before work hardening. Two dimensional finite element analyses have shown that fracture parameters, such as the J-integral, are very sensitive to variation in material law for shallow cracks, and the writers have now commenced three dimensional analyses for surface semi-elliptical cracks in plates. Some computations have been made for specimens tested experimentally by Dodds and Read [1], and the results show that what appears to be a reasonable approximation of the material law is inadequate in modelling the deformation behaviour, and that more accurate modelling of the material law, especially the plastic part immediately after yield, which may include perfectly plastic behaviour, is required for reliable results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00018513
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  • 9
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    J-integral estimation for single edge notch specimens in tension (1993)
    Springer
    Details
    Publication Date: 1993-09-01
    Print ISSN: 0376-9429
    Electronic ISSN: 1573-2673
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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  • 10
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    The sensitivity of J-integrals to material law variations for semi-elliptical surface cracks (1996)
    Springer
    Details
    Publication Date: 1996-01-01
    Print ISSN: 0376-9429
    Electronic ISSN: 1573-2673
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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