Crack growth analyses and correlations for attachment lugs

Kathiresan, K.; Brussat, T. R.; Rudd, JL

doi:10.2514/6.1983-842

Cited by 6 publications

(7 citation statements)

References 6 publications

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“…A crack initiates at each outer corner of the slit, and then grows along the circumferential and thickness directions with different growth rates similar to corner crack growth [8]. Therefore, it is reasonable to consider the crack length in this research only after a through-crack is completed [8,15]. Then the length of the precrack is defined along the circumferential direction on the mean radius as…”

Section: Experiments and Discussionmentioning

confidence: 99%

Fatigue Crack Growth Behaviour of Sm45c Steel Under Mixed‐mode I and Ii Loading

You

Lee

1998

Fatigue Fract Eng Mat Struct

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The practical applications of studies related to constant amplitude mode I loading are somewhat limited in situations where more than one mode exists. So, criteria, rules and laws for these situations have to be validated with experiments. This paper extends previous results by the authors for mixed‐mode I and II fatigue loading. An effective stress intensity factor range which considers crack closure and crack surface interference is described for the analysis of a crack under mixed‐mode I and II fatigue loadings, and this factor is assessed from experimental results.

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Section: Experiments and Discussionmentioning

confidence: 99%

Fatigue Crack Growth Behaviour of Sm45c Steel Under Mixed‐mode I and Ii Loading

You

Lee

1998

Fatigue Fract Eng Mat Struct

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“…The analysis included the influence of fracture stress, critical crack length, and the angles of crack trajectory inclination, which were taken as random variables. The assessment of damage tolerance of aircraft attachment lugs was developed by Kathiresan et al (1984). Solutions of stress distributions and stress intensity factors were obtained for various parameters.…”

Section: Stress Intensity Factormentioning

confidence: 99%

Overview of Structural Life Assessment and Reliability, Part I: Basic Ingredients of Fracture Mechanics

Ibrahim¹

2015

j ship prod des

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Structural life assessment periodically evaluates the state and condition of a structural system and provides recommendations for possible maintenance actions or the end of structural service life. It is a diversified field and relies on the theories of fracture mechanics, fatigue damage process, probability of failure, and reliability. With reference to naval ship structures, their life assessment is not only governed by the theory of fracture mechanics and fatigue damage process, but by other factors such as corrosion, grounding, and sudden collision. The purpose of this series of review articles is to provide different issues pertaining to structural life assessment of ships and ocean structures. Part I deals with the basic ingredients of the theory of fracture mechanics, which is classified into linear elastic fracture mechanics and elasto-plastic fracture mechanics. The amount of energy available for fracture is usually governed by the stress field around the crack, which is measured by the stress intensity factor. The value of the stress intensity factor, which depends on the loading mode, is evaluated by different methods developed by many researchers. The applications of the theory of fracture mechanics to metallic and composite structures are presented with an emphasis to those used in marine structures. When the inertia of relatively large pieces of a structure is large enough that the correct balancing of the energy of fracture requires the inclusion of kinetic energy, then the dynamic nature of fracture dominates the analysis. For a crack that is already propagating, the inertial effects are important when the crack tip speed is small compared with the stress wave velocities. This fact has been realized in the theory of fracture mechanics under the name of dynamic fracture and peridynamic. In essence, peridynamic replaces the partial differential equations of classic continuum theories with integro-differential equations as a tool to avoid singularities arising from the fact that partial derivatives do not exist on crack surfaces and other singularities. A brief overview of fracture dynamics and peridynamics together with damage mechanisms in composite structures is presented. The limitations of fracture mechanics criteria are also discussed. Life assessment of ship structures depends on the failure modes and the probabilistic description of failure, which are addressed in Part II. Life assessment of ship structures depends on the failure modes and the probabilistic description of failure. In view of structural parameter uncertainties, probabilistic analysis requires the use of reliability methods for assessing fatigue life by considering the crack propagation process and the first passage problem, which measures the probability of the exit time from a safe operating regime. The main results reported in the literature pertaining to ship structural damage assessments resulting from to slamming loads, liquid sloshing impact loads of liquefied natural gas in ship tankers, and ship grounding accidents, an...

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“…Cracks grow with a 'quarter elliptical shape', maintaining the surface dimension, 'c', larger than the depth dimension, 'a', while it is well known that the stress intensity factor in a pin load joint containing a quarter circular shape crack is higher in the thickness direction compared with surface direction; this result was confirmed experimentally in several papers, see for instance. [9][10][11][12][13] The surface dimension crack was monitored by a crack propagation gauge having twenty ties, pitch 1.15 mm, while crack depth dimension was numerically evaluated in such a way as to transform the initial crack, having dimensions a 0 = c 0 = 2.3 mm, to the final crack observed in Fig. 11, having a = 13.4 mm and c = 24.3 mm.…”

Section: Crack Propagation Under Constant Amplitude Loading On Lug Spmentioning

confidence: 99%

Fatigue crack propagation in the wing to fuselage connection of the new trainer aircraft M346

Lanciotti

Nigro

Polese

2006

Fatigue Fract Eng Mat Struct

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A B S T R A C T The series version of the M346 military trainer aircraft is currently under construction atAermacchi (Venegono Superiore, Italy). The design target life of the aircraft, which will be certified for Damage Tolerance, is 12 000 flight hours (FH), with the possible extension to 16 000 FH after specific inspections. Fatigue tests were performed on critical elements at the Department of Aerospace Engineering at University of Pisa in order to verify crack propagation calculations. The wing to fuselage connection is one of the most interesting elements from the fatigue point of view. Spars and frames, both integrally machined, are connected by two lug-fork joints; the base material is aluminium alloy 7050-T7451 for both the elements. High interference bushings, ForceMate ® , produced by FTI (Fatigue Technology Inc., Seattle, WA) were used in the lug/fork connections.Experimental activity was carried out on two different specimens. The first, a Compact Tension specimen, was tested under constant amplitude loading to verify the fatigue crack growth rate data contained in NASGRO 4, the software used for Damage Tolerance evaluations. Experimental results were fully comparable with the NASGRO 4 material database. Additional variable amplitude loading tests were carried out in order to calibrate crack growth prediction models used in the analyses.The second specimen was a lug-fork joint designed as the actual joints present on the aircraft. Both constant and variable amplitude loading fatigue tests were carried out in this case too. Results obtained clearly indicated the beneficial effect of ForceMate bushings, compared to shrink fit bushings.

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Crack growth analyses and correlations for attachment lugs

Cited by 6 publications

References 6 publications

Fatigue Crack Growth Behaviour of Sm45c Steel Under Mixed‐mode I and Ii Loading

Fatigue Crack Growth Behaviour of Sm45c Steel Under Mixed‐mode I and Ii Loading

Overview of Structural Life Assessment and Reliability, Part I: Basic Ingredients of Fracture Mechanics

Fatigue crack propagation in the wing to fuselage connection of the new trainer aircraft M346

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