Crack growth at low ?<i>K</i>’s and the Frost‐Dugdale law

Jones, Rhys; Barter, Simon; Molent, L.; Pitt, Susan

doi:10.1080/02533839.2004.9670938

Cited by 19 publications

(7 citation statements)

References 10 publications

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“…This expression coincides with that presented in [40,41,43]. More details on this derivation are given in 0.…”

Section: Cracks As Fractalssupporting

confidence: 69%

A multi-scale approach to crack growth

Jones¹,

Barter²,

Molent³

et al.

Multiscaling in Molecular and Continuum Mechanics: Interaction of Time and Size From Macro to Nano

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This work first examines the fatigue crack growth histories (from microns to millimetres) of a range of test specimens and service loaded components and concludes that in most cases rack growth follows the generalised Frost and Dugdale crack growth law, i.e. as a first approximation there is a linear relationship between the log of the crack length or depth and the service history (number of cycles). It is then shown how the Frost and Dugdale crack growth law, incomplete self-similarity, the two parameter crack growth model, and fractal fatigue concepts are related. Also shown are how this law can be used to predict crack growth from sub microns to mm's in a range of full-scale aircraft fatigue tests and coupon tests, including aircraft fuselage lap-joints.

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“…This expression coincides with that presented in [40,41,43]. More details on this derivation are given in 0.…”

Section: Cracks As Fractalssupporting

confidence: 69%

A multi-scale approach to crack growth

Jones¹,

Barter²,

Molent³

et al.

Multiscaling in Molecular and Continuum Mechanics: Interaction of Time and Size From Macro to Nano

Self Cite

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“…The data in Region II is usually fitted by a two-parameter equation of the type advocated in Paris et al (1961) and Paris (1962). A slope of n ≈ 4 has been found for the data in Broek and Schijve (1963) which does not satisfy the self-similar crack growth condition of n ¼ 2 as pointed in Liu (1959Liu ( , 1963, Jones et al (2004), and Jones and Pitt (2006). When other parameters are used to correlate the da/dN data, the resulting slopes of the tangent lines in Region II are likely to be altered.…”

Section: Central Pre-cracked 2024-t3 Aluminum Panel Specimensmentioning

confidence: 83%

“…Other models of relation da/dN to a combination of f(a) and ΔK have been considered (Vasudevan et al, 1994;Newman et al, 2004;Noroozi et al, 2005;Jones et al, 2004;Jones and Pitt, 2006). In particular, the works in Jones et al (2004) and Jones and Pitt (2006) have used data for small cracks with a≈1-1.8 mm. Straight lines fits have been obtained for data in Regions I and II although the definition of small and/or shorts in Region I remains open.…”

Section: Discussionmentioning

confidence: 99%

“…For microstructural defects referred to as small and/or short cracks, other models have been introduced (McDowell and Bennet, 1996;McDowell, 1997;Wang, 1996;Wang and Miller, 1992) as refinement of the macroscopic fracture mechanics approach to IJSI 6,4 fatigue (Paris et al, 1961;Paris, 1962;Liu, 1959Liu, , 1963, crack closure (Vasudevan et al, 1994;Newman et al, 2004) and other effects (Noroozi et al, 2005) have also been discussed. A resurgent of interest to further review the different models and to find the reasons why the correlation of the small crack growth data can be better in some cases and not in others ( Jones et al, 2004;Jones and Pitt, 2006). Similitude of crack growth was one of the explanations offered ( Jones and Pitt, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Micro/macro fatigue crack growth rate model for 2024-T3 aluminum panel

Sih

2015

International Journal of Structural Integrity

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2015),"Three-dimensional cracked discs under anti-plane loading and effects of the boundary conditions: A review of recent developments"If you would like to write for this, or any other Emerald publication, then please use our Emerald for Authors service information about how to choose which publication to write for and submission guidelines are available for all. Please visit www.emeraldinsight.com/authors for more information. About Emerald www.emeraldinsight.comEmerald is a global publisher linking research and practice to the benefit of society. The company manages a portfolio of more than 290 journals and over 2,350 books and book series volumes, as well as providing an extensive range of online products and additional customer resources and services. AbstractPurpose -Fatigue crack growth rate data for 2024-T3 aluminum are found using three parameters d*, σ* and μ* for short and long cracks for Regions I-III in conventional fatigue. Asymptotic solution of a line crack with a micro-tip is found to yield a singular stress behavior of order 0.75 in contrast to the 0.50 order known for the macrocrack. The difference is due to the micro-macro interaction effects. The three parameters account for the combined effects of load, material and geometry via the tip region. Data for short and long cracks lie on a straight with a slope of about 3.9-4.8 for R values of 0.286-0.565. The results were based on an initial crack a⩾1 mm where a is the half length for a central crack panel. The paper aims to discuss these issues. Design/methodology/approach -The belief that specimen fatigue data could assist the design of structural components was upended when FAA discovered that the NASGRO FCGD are not valid for short cracks that are tight and may even be closed. The regular ΔK vs da/dN model was limited to long cracks. The issue become critical for short cracks connecting the long ones of a few mm to cm or even m according to da/dN for the same crack history. The danger of short/long fatigue crack growth (SLFCG) prompted FAA to introduce an added test known as Limit of Validity (LOV), a way of setting empirical limits for structural components. The dual scale SLFCG data from ΔK micro/macro provide support for the LOV tests. Findings -Data for short and long cracks lie on a straight with a slope of about 3.9-4.8 for R values of 0.286-0.565. The single dual scale relation on ΔK micro/macro can switch from microscopic to macroscopic or vice and versa. The difference is fundamental. Order other than 0.75 can be obtained for simulating different microstructure effects as well as different materials and test conditions. Originality/value -Scale shifting from short to long fatigue cracks for 2024-T3 aluminum is new. The crack driving force is found to depend on the crack tightness. The sigmoidal curve based on the regular ΔK plot disappeared. The data from ΔK micro/macro for short cracks may supplement the FAA LOV tests for setting more reliable fatigue safe limits.

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“…In summary, the proposed model accounting for load-amplitude effects, based on the form of da/dN at a given load amplitude P 0 , can be described by equations (6), (10), and (11).…”

Section: Effect Of Load-amplitude Variationmentioning

confidence: 99%

Effects of heterogeneity and load amplitude on fatigue rate prediction of a welded joint

Zhang

Jiang

Lü

et al. 2016

Advances in Mechanical Engineering

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It is a contradiction to homogeneous material fatigue behavior characterized by widely used linear Paris law, welded-joint fatigue issues need to be reassessed because fatigue crack growth behavior going through heterogeneous region will be different. For a welded joint, log(da/dN) is no longer linearly related to log(DK) in heterogeneous region because of the change in fatigue properties resulting from the welding process. Theoretical model of the fatigue crack growth rate without artificial adjustable parameters was proposed by considering the effects of heterogeneity in a welded joint and load-amplitude variation on fatigue crack growth curve. In this fatigue heterogeneous region, the relationship between log(da/dN) and log(DK) is similar to a concave-down parabola. Predicted results from the proposed model agreed better with the experimental data obtained from fatigue tests conducted in this study and open published literatures for welded joints in comparison to the widely used Paris model.

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Crack growth at low ?K’s and the Frost‐Dugdale law

Cited by 19 publications

References 10 publications

A multi-scale approach to crack growth

A multi-scale approach to crack growth

Micro/macro fatigue crack growth rate model for 2024-T3 aluminum panel

Effects of heterogeneity and load amplitude on fatigue rate prediction of a welded joint

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