Engineering critical analyses to BS 7910 — the UK guide on methods for assessing the acceptability of flaws in metallic structures

Wiesner, C.S.; Maddox, S. J.; Xu, Wang; Webster, G. A.; Burdekin, F.M.; Andrews, Robert M.; Harrison, Jamie

doi:10.1016/s0308-0161(01)00011-4

Cited by 151 publications

(19 citation statements)

References 2 publications

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“…They can be used to evaluate failure criteria for modeling fracture propagation (Brace, 1960;Lawn, 1993;Paris & Erdogan, 1963). They have become a key part of fitness-for-purpose analyses when considering the impact of interacting cracks on a material's lifetime (Wiesner et al, 2000). SIFs have also been used in geological models to predict fracture behavior (Olson, 2004;Paluszny & Zimmerman, 2013;Philip et al, 2005;Renshaw & Pollard, 1994) but have not been routinely adopted for investigating geological fracture interaction.…”

Section: Introductionmentioning

confidence: 99%

Quantification of Fracture Interaction Using Stress Intensity Factor Variation Maps

2017

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Accurate and flexible models of fracture interaction are sought after in the fields of mechanics and geology. Stress intensity factors (SIFs) quantify the energy concentrated at the fracture tips and are perturbed from their isolated values when two fractures are close to one another. Using a three‐dimensional finite element fracture mechanics code to simulate static fractures in tension and compression, interaction effects are examined. SIF perturbations are characterized by introducing three interaction measures: the circumferential and maximum SIF perturbation provide the “magnitude” of the effect of interaction, and the amplification to shielding ratio quantifies the balance between increased and decreased SIFs along the tip. These measures are used to demonstrate the change in interaction with fracture separation and to find the separation at which interaction becomes negligible. Interaction maps are constructed by plotting the values of the interaction measures for a static fracture as a second fracture is moved around it. These maps are presented for several common fracture orientations in tension. They explore interaction by highlighting regions in which growth is more likely to occur and where fractures will grow into nonplanar geometries. Interaction maps can be applied to fracture networks with multiple discontinuities to analyze the effect of geometric variations on fracture interaction.

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Section: Introductionmentioning

confidence: 99%

Quantification of Fracture Interaction Using Stress Intensity Factor Variation Maps

2017

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“…Thus, collapse analysis as a subject is mostly forgotten in the mainstream fracture mechanics community. However, one can still find some discussion of collapse in the context of the development of failure assessment diagrams used to describe the rupture of pipes, pressure vessels, and other thin‐shell structures made of especially ductile or defect‐tolerant materials . The critical net section stress analysis used by Broek et al .…”

Section: Resultsmentioning

confidence: 61%

Reconciling fracture toughness parameter contradictions in thin ductile metal sheets

Lanning

Javaid

Muhlstein

2017

Fatigue Fract Eng Mat Struct

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A B S T R A C T The well-known trade-off between strength and fracture toughness in bulk specimens is often used to explain the low fracture toughness of very thin ductile face-centred cubic metal specimens, but this interpretation contradicts the relative length scales of thickness-dependent strength and thickness-dependent fracture toughness. This study uses the concept of similitude to demonstrate that linear elastic fracture mechanics analysis of 25.4 μm thick annealed aluminium is invalid, although the resulting fracture toughness measurements fit well with the existing literature and idea of a strength/fracture toughness trade-off. Similarly, an elastic plastic fracture mechanics analysis is sensitive to out-of-plane deformation that cannot be practically eliminated or corrected for with a model. However, a plastic collapse analysis using a critical net section stress criterion is demonstrably valid by the concept of similitude, is insensitive to out of plane deformation, and agrees with the evidence of extensive plasticity in the fracture surfaces.Keywords ductile tearing; fracture mechanics; fracture toughness; plastic collapse; stable crack growth; thin sheet. N O M E N C L A T U R Ea = crack length in SE(T) specimen or half crack length in M(T) specimen Atot = total work applied to specimen A tot ¼ ∫ Δ 0 Pd Δ b = uncracked ligament length B, B 0 , B * = thickness, minimum thickness for plane strain, critical thickness J, J max = J-integral, maximum valid J measurement for a given specimen goemetry K = stress intensity factor K Ic , K R = fracture toughness in mode I loading, propagation toughness in K-R analysis L À = mean lineal intercept grain size LEFM, EPFM = linear elastic fracture mechanics, elastic-plastic fracture mechanics M(T) = middle crack tension specimen geometry P = force applied to specimen R = load ratio σ min /σ max used in fatigue precracking SE(T) = single edge crack tension specimen geometry t = traction acting normal to J-integral path Γ u = displacement vector at a point along path Γ w = width of SE(T) or half width of M(T) specimens W = strain energy density x, y = in-sheet coordinate axes perpendicular and parallel to tensile stress, respectively Y = geometric correction factor used in computation of K ¼ σ Y ffiffiffiffiffiffi π a p Correspondence: C. L. Muhlstein.

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“…If elastic stress distributions have not been linearised, the extent of the regions, at the inner and outer surfaces, (r p ) i and (r p ) o respectively, over which inequality (14) is violated should be identified. Limited regions of the structure may be exempted from the strict shakedown requirement if at least 80% of the thickness of every section consists of a ligament over which the criterion is continuously satisfied.…”

Section: Procedures Of R5 Volume 2/3mentioning

confidence: 99%

R5 procedures for assessing structural integrity of components under creep and creep–fatigue conditions

Ainsworth¹

2006

International Materials Reviews

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The R5 high temperature assessment procedures have been developed in the UK and address both creep-fatigue crack initiation in initially defect free components and the growth of flaws by creep and creep-fatigue mechanisms. The procedures were developed some time ago and included a number of novel features such as: the shakedown reference stress approach for structural assessment; the ductility exhaustion method for estimating creep damage; the inclusion of size effects in fatigue damage calculations to enable assessments of thin section components; and the treatment of the effects of crack closure on creep-fatigue crack growth rates. Recently, the R5 procedures have undergone a major revision leading to Issue 3 of the document. In the revision, the above novel features have been retained but other parts of the procedure have been modified. These include: a restructuring of the document with associated new step-by-step procedures to enable easier application; modifications to the ductility exhaustion model to address multiaxial stresses including the triaxial stresses which may be present in regions of high welding residual stress; additional advice for assessment of weldments including fatigue strength reduction factors based on experimental data on austenitic weldments; generalised hysteresis loop construction methods for complex non-isothermal cycles, supported by laboratory data collected under non-isothermal conditions; advice on inelastic analysis when simplified shakedown methods are inapplicable; and rules for determination of interactions between creep and fatigue crack growth. The present review first describes in outline the overall structure and content of R5 Issue 3. Then the new R5 creep-fatigue crack initiation assessment procedures are set out in more detail. This includes the recent modifications and some associated background experimental and analytical work on which these modifications are based. Finally, the paper sets out the new creep-fatigue crack growth procedures in R5, again with some background information on the recent developments.

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Engineering critical analyses to BS 7910 — the UK guide on methods for assessing the acceptability of flaws in metallic structures

Cited by 151 publications

References 2 publications

Quantification of Fracture Interaction Using Stress Intensity Factor Variation Maps

Quantification of Fracture Interaction Using Stress Intensity Factor Variation Maps

Reconciling fracture toughness parameter contradictions in thin ductile metal sheets

R5 procedures for assessing structural integrity of components under creep and creep–fatigue conditions

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