Fatigue crack propagation in oil environments—I. Crack growth behavior in silicone and paraffin oils

Tzou, J.-L.; Suresh, S.; Ritchie, Robert O.

doi:10.1016/0001-6160(85)90224-x

Cited by 46 publications

(16 citation statements)

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“…The shielding effect of hydrodynamic pressure has been modeled analytically [29,30] and numerically [38] for fatigue crack growth in metals. As shown schematically in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Crack growth rates measured in oils were lower than in air. Greater reductions in crack growth rate occurred for higher viscosity oils [26][27][28], until an upper limit was reached and the fluid could no longer penetrate to the crack tip [29,30]. For metals, crack-tip shielding from hydrodynamic pressure provided nearly 50% reduction in crack growth rate [29,31].…”

Section: Introductionmentioning

confidence: 99%

“…Greater reductions in crack growth rate occurred for higher viscosity oils [26][27][28], until an upper limit was reached and the fluid could no longer penetrate to the crack tip [29,30]. For metals, crack-tip shielding from hydrodynamic pressure provided nearly 50% reduction in crack growth rate [29,31].In this work, we present a new methodology for retardation and repair of fatigue cracks based on the self-healing concept developed by White et al [32]. In Part I we investigate two crack-tip shielding mechanisms during fatigue of a microcapsule toughened epoxy.…”

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confidence: 99%

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Retardation and repair of fatigue cracks in a microcapsule toughened epoxy composite – Part I: Manual infiltration

Brown

White

Sottos

2005

Composites Science and Technology

216

117

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As a first step towards a new crack healing methodology for cyclic loading, this paper examines two promising crack-tip shielding mechanisms during fatigue of a microcapsule toughened epoxy. Artificial crack closure is achieved by injecting precatalyzed monomer into the crack plane to form a polymer wedge at the crack tip. The effect of wedge geometry is also considered, as dictated by crack loading conditions during infiltration. Crack-tip shielding by a polymer wedge formed with the crack held open under the maximum cyclic loading condition (K max ) yields temporary crack arrest and extends the fatigue life by more than 20 times. Hydrodynamic pressure and viscous damping as a mechanism of crack tip shielding are also investigated by injecting mineral oil into the crack plane. Viscous fluid flow leads to retardation of crack growth independent of initial loading conditions. The success of these mechanisms for retarding fatigue crack growth demonstrates the potential for in situ self-healing of fatigue damage.Keywords: A. smart materials, A. polymer-matrix composites, B. fatigue, C. failure criterion, self-healing Submitted for publication in Composites Science and Technology (2005) 2 IntroductionThermosetting polymers are used in a wide variety of applications ranging from structural composites to microelectronics. Due to low strain-to-failure, these polymers are highly susceptible to damage in the form of cracks. In structural composites these cracks can lead to fiber/matrix debonding and inter-ply delamination, ultimately resulting in component failure. Susceptibility to cyclic loading is particularly problematic because a crack will grow, however slowly, above a threshold range of stress intensities ΔK th that is significantly lower than the critical stress intensity K IC . Prevention of fatigue failure currently depends on accurate life prediction and implementation of inspection procedures.Polymer fatigue has been studied extensively in both homogeneous and composite structures (e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]). In most polymers, fatigue crack growth rates (da/dN) are accurately described by the Paris power law [16],where C 0 and n are material constants and ΔK I is the applied range of stress intensity. Typical Paris power law crack growth behavior is shown schematically by the solid curve in Fig. 1. Despite this understanding of cyclic crack growth, fatigue failure remains a major cause of component failure. Fig. 1. Representative relationship between fatigue crack growth rate (da/dN) and the applied stress intensity range (ΔK I ) in the Paris power law region. Improved fatigue behavior can be obtained by: (a) increasing the range of stress intensity before crack growth instability ΔK ult , (b) reducing the crack growth rate da/dN for a given ΔK I , (c) reducing the crack growth rate sensitivity to ΔK I , i.e. reduce n, or (d) increasing the threshold ΔK th at which crack growth arrests.Strategies for improving fatigue life are shown schematically in Fig. 1 and includ...

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“…The shielding effect of hydrodynamic pressure has been modeled analytically [29,30] and numerically [38] for fatigue crack growth in metals. As shown schematically in Fig.…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Retardation and repair of fatigue cracks in a microcapsule toughened epoxy composite – Part I: Manual infiltration

Brown

White

Sottos

2005

Composites Science and Technology

216

117

View full text Add to dashboard Cite

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“…Different loading conditions in these two environments may be caused by high local stresses due to ultrasonic cavitation in distilled water. Additionally, hydrodynamic wedging of the water in the wake of the crack may increase the crack closure level 30 . These may be reasons for different loading conditions between water in the wake of the crack and capillary condensed water at the crack tip.…”

Section: Discussionmentioning

confidence: 99%

Influence of atmospheric moisture on slow fatigue crack growth at ultrasonic frequency in aluminium and magnesium alloys

Papakyriacou

Mayer

Fuchs

et al. 2002

Fatigue Fract Eng Mat Struct

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The deleterious influence of atmospheric moisture on the fatigue properties of an aluminium wrought alloy AlZnMgCu1.5‐T6, an aluminium cast alloy AlSi9Cu3 and magnesium cast alloys AM60 hp, AZ91 hp and AS21 hp has been studied at a cycling frequency of 20 kHz. Atmospheric moisture accelerates fatigue crack growth and decreases the threshold stress intensities to 55–75% of the respective values in vacuum. In ambient air, fatigue crack growth rates were up to two decades higher than those in vacuum. Accelerated crack growth was found at propagation rates below about 2 × 10−9 m cycle−1 in aluminium alloys and below about 3 × 10−8 m cycle−1 in magnesium alloys. As the threshold regime is approached, fatigue cracks in ambient air either propagate at a minimum mean growth rate on average of approximately one lattice spacing per cycle or they stop propagating, whereas mean growth rates of 10−12 m cycle−1 were found in vacuum. Crack initiation and slow fatigue crack growth mainly determine lifetimes in the high cycle regime, and endurance data obtained at ultrasonic frequency in ambient air of 40–60% relative humidity are similar to lifetimes measured at conventional frequencies.

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“…Ritchie et al [7] and Suresh [8,9] identified the main closure mechanisms, which are plasticity induced crack closure (PICC), oxide induced crack closure and roughness induced crack closure. Additional mechanisms, such as viscous-fluid induced crack closure [10], transformation-induced crack closure [11] and graphite induced crack closure [12], have been observed to operate in susceptible materials and environments.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of plasticity induced crack closure: Identification and discussion of parameters

Antunes

Rodrigues

2008

Engineering Fracture Mechanics

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Numerical studies play a major role in the understanding and prediction of plasticity induced crack closure (PICC). However, the available numerical models can be considered simplifications of reality as they consider discrete crack propagations, relatively high fatigue crack growth rates (FCGR), sharp cracks, and propagation occurring at well-defined loads. Besides, there are a great number of numerical and physical parameters affecting the predictions of PICC. The aim of this paper is to discuss the numerical study of PICC. The numerical parameters affecting the accuracy of the numerical simulations, and the dependent parameters used to characterise the plastic wake and the closure level, are identified. The influence of the radial size of crack front elements and crack propagation is analysed. An extrapolation model is proposed, with excellent results. An intrinsic uncertainty is associated with the number of load cycles between crack increments and the definition of crack closure level. Finally, the effect of the stress ratio (R) on crack closure level is analysed.

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Fatigue crack propagation in oil environments—I. Crack growth behavior in silicone and paraffin oils

Cited by 46 publications

References 38 publications

Retardation and repair of fatigue cracks in a microcapsule toughened epoxy composite – Part I: Manual infiltration

Retardation and repair of fatigue cracks in a microcapsule toughened epoxy composite – Part I: Manual infiltration

Influence of atmospheric moisture on slow fatigue crack growth at ultrasonic frequency in aluminium and magnesium alloys

Numerical simulation of plasticity induced crack closure: Identification and discussion of parameters

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