A study of fatigue within the framework of the kinetic concept of fracture

Regel, V. R.; Leksovsky, A. M.

doi:10.1007/bf00182688

Cited by 41 publications

(14 citation statements)

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“…In the case of many independently loaded samples, the average lifetime is τ = τ 0 / p ( σ ), where p ( σ ) is the probability of sample failure under stress σ . Therefore, rearranging Equation gives:

p (σ) = \exp (- \frac{U_{0} - γ σ_{x}}{italickT})

It was suggested by Regel and Leksovsky [] that a relationship similar to Equation holds for cyclic fatigue after adjustment of parameters τ 0 , U 0 , and γ .…”

Section: Discussionmentioning

confidence: 99%

“…Analytical expressions are usually obtained by fitting a power law to the experimentally determined S‐N curves. This fit however, is not very accurate, and in some cases the experimental data support a relationship similar to Equation [ Regel and Leksovsky , ]. Assuming that fatigue failure is caused by the maximum value of thermal stress, Equation , then the probability of failure under cyclic load with amplitude σ x is given by Equation .…”

Section: Discussionmentioning

confidence: 99%

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In situ fragmentation and rock particle sorting on arid hills

et al. 2013

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[1] Transport processes are often proposed to explain the sorting of rock particles on arid hillslopes, where mean rock particle size often decreases in the downslope direction. Here we show that in situ fragmentation of rock particles can also produce similar patterns. A total of 93,414 rock particles were digitized from 880 photographs of the surface of three mesa hills in the Great Sandy Desert, Australia. Rock particles were characterized by the projected Feret's diameter and circularity. Distance from the duricrust cap was found to be a more robust explanatory variable for diameter than the local hillslope gradient. Mean diameter decreased exponentially downslope, while the fractional area covered by rock particles decreased linearly. Rock particle diameters were distributed lognormally, with both the location and scale parameters decreasing approximately linearly downslope. Rock particle circularity distributions showed little change; only a slight shift in the mode to more circular particles was noted to occur downslope. A dynamic fragmentation model was used to assess whether in situ weathering alone could reproduce the observed downslope fining of diameters. Modeled and observed size distributions agreed well and both displayed a preferential loss of relatively large rock particles and an apparent approach to a terminal size distribution of the rocks downslope. We show this is consistent with a size effect in material strength, where large rocks are more susceptible to fatigue failure under stress than smaller rocks. In situ fragmentation therefore produces qualitatively similar patterns to those that would be expected to arise from selective transport.

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p (σ) = \exp (- \frac{U_{0} - γ σ_{x}}{italickT})

It was suggested by Regel and Leksovsky [] that a relationship similar to Equation holds for cyclic fatigue after adjustment of parameters τ 0 , U 0 , and γ .…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

In situ fragmentation and rock particle sorting on arid hills

et al. 2013

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“…This time will be less than the actual fracture time and it will depend on the nature of the load variation. For some materials, such as polyacrylonitrile fibers or PMMA films good agreement has been reported between the variation with stress of both the static lifetime and the cyclic lifetime under sinusoidal loading [52]. However, in other materials, differences arise and these have been attributed to changes of the structure-sensitive parameter y with temperature and stress and also to changes produced by the hysteresis self-heating effect.…”

Section: Inl Journ Of Fracture 16 (1980) 499-532mentioning

confidence: 92%

Fatigue of polymers

1980

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The general nature of fracture in polymers, when subject to alternating loads as distinct from static or steadily increasing loads, is reviewed; and the molecular mechanisms and micromechanics aspects of the fatigue fracture process are discussed. Some attention is given to thermal fatigue, where fracture results primarily from a large specimen temperature rise due to hysteresis heating. However, primary emphasis is devoted to mechanical fatigue, in which fracture is a result of initiation and propagation of a crack, as a result of the periodic nature of the applied load.Attention is given to the important internal, or material, variables such as polymer structure, molecular weight, crosslinking, and filler or diluent type and content; and to significant external variables such as stress or stress intensity factor amplitude, mean stress, temperature, frequency and environment. Various methods that can be utilized to provide significant degrees of enhancement in the fatigue resistance of polymers are outlined and discussed.

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“…In addition, frequency has no effect on the fatigue lifetime, which is in agreement with other fatigue analyses. 18,23,24 Figure 5a elucidates the method to perform cyclic fatigue life predictions by shifting a set of creep life data along the time axis. The magnitude of the horizontal shift a cyclic depends on the ratio of the stress amplitude σ ampl applied, the material's stress dependence σ 0 , and the wave form applied only.…”

Section: An Analysis To the Time-dependent Fatigue Failurementioning

confidence: 99%

An Analytical Method To Predict Fatigue Life of Thermoplastics in Uniaxial Loading: Sensitivity to Wave Type, Frequency, and Stress Amplitude

2008

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A method is presented that allows fatigue life predictions on the basis of creep life data. The approach is based on the assumption that the time-dependent failure of polymers is determined by the intrinsic strain softening that is initiated when a critical threshold value of the plastic strain is surpassed. To facilitate fatigue predictions, an acceleration factor is defined that indicates how much faster plastic strain is accumulated by a cyclic signal compared to its static mean stress. Analytical solutions of the acceleration factor are presented for triangular and square waves, which predict that only the stress amplitude of the cyclic signal and the material's stress dependency affect fatigue life, whereas frequency plays no role. Verification using several glassy and semicrystalline polymers demonstrates that this method yields accurate quantitative lifetime predictions not only for polymers that exhibit ductile failure but also for those that display brittle fracture, provided that fracture is preceded by (localized) plastic flow.

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A study of fatigue within the framework of the kinetic concept of fracture

Cited by 41 publications

References 1 publication

In situ fragmentation and rock particle sorting on arid hills

In situ fragmentation and rock particle sorting on arid hills

Fatigue of polymers

An Analytical Method To Predict Fatigue Life of Thermoplastics in Uniaxial Loading: Sensitivity to Wave Type, Frequency, and Stress Amplitude

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