Notch effect in low cycle fatigue

Bentachfine, S.; Pluvinage, G.; Gilgert, J.; Azari, Z.; Bouami, Driss

doi:10.1016/s0142-1123(99)00004-3

Cited by 37 publications

(17 citation statements)

References 8 publications

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“…A number of different multi‐axial predictive models have been proposed recently in the literature to deal with notches of different geometry, capable of provoking stress concentrations with different severity 21–37 …”

Section: Introductionmentioning

confidence: 99%

Multiaxial fatigue of V-notched steel specimens: a non-conventional application of the local energy method

Berto

Lazzarin

Yates

2011

Fatigue &Amp; Fracture of Engineering Materials &Amp; Structures

150

132

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A B S T R A C T The paper deals with the multi-axial fatigue strength of notched specimens made of 39NiCrMo3 hardened and tempered steel. Circumferentially V-notched specimens were subjected to combined tension and torsion loading, both in-phase and out-of-phase, under two nominal load ratios, R = −1 and R = 0, also taking into account the influence of the biaxiality ratio, λ = τ a /σ a . The notch geometry of all axi-symmetric specimens was a notch tip radius of 0.1 mm, a notch depth of 4 mm, an included V-notch angle of 90 • and a net section diameter of 12 mm. The results from multi-axial tests are discussed together with those obtained under pure tension and pure torsion loading on plain and notched specimens. Furthermore the fracture surfaces are examined and the size of nonpropagating cracks measured from some run-out specimens at 5 million cycles. Finally, all results are presented in terms of the local strain energy density averaged in a given control volume close to the V-notch tip. The control volume is found to be dependent on the loading mode.Keywords multiaxial fatigue; notch stress intensity factor (NSIF); strain energy density (SED); torsion loading; V-notched. N O M E N C L A T U R E2α = V-notch included angle = Phase angle λ = Biaxiality ratio, τ a /σ a λ 1 = Eigenvalue of the mode I stress distribution, according to Williams's solution λ 3 = Eigenvalue of the mode III stress distribution ρ = Notch root radius σ a = Nominal stress amplitude referred to the net area of the specimens τ a = Nominal stress amplitude due to torsion loading (on the net area) σ A, τ A = Fatigue strength (in terms of stress amplitudes on the net area) at N A cycles to failure σ y = Yield stress σ y = Cyclic yield stress c np = Non-propagating crack length according to Yu, Tanaka and Akiniwa's model e 1 , e 3 = Parameters used for the energy density evaluation k = Inverse slope of the fatigue curves K 1 , K 3 = Mode I and mode III notch stress intensity factors (NSIFs) K th = Threshold value of the stress intensity factor K IIIsh th = Shielding stress intensity factor under mode III loading according to Yu et al. k 1 , k 3 = Non-dimensional factors used in the NSIF expressions Correspondence: P. Lazzarin.

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Section: Introductionmentioning

confidence: 99%

Multiaxial fatigue of V-notched steel specimens: a non-conventional application of the local energy method

Berto

Lazzarin

Yates

2011

Fatigue &Amp; Fracture of Engineering Materials &Amp; Structures

150

132

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“…The stress- [21,22] as well as the strain- [23] point approach has been extended to estimate the S-N curve from low to high cycle fatigue regime. The more simple and diffused approach is to assume x 0 as a constant and to define fatigue design curves on the basis of a statistical analysis of a significant number of experimental results.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Strain energy-and stress-based approaches revisited in notch fatigue of ductile steels

2018

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Abstract. The constant amplitude, zero-mean stress, axial-fatigue behaviour of plain and bluntly notched AISI 304 L stainless steel specimens is investigated in terms of strain energy density. Concerning plain material, it was found that at the fatigue knee the plastic strain energy density is 1.49 times higher than the elastic strain energy density. In the authors' opinion, the presence of plasticity at the fatigue knee is responsible for the unsuitableness of classical stress -based approaches to synthesise the fatigue behaviour of this material. On the contrary, the elastic-plastic strain energy density was found an efficient parameter to rationalise in a single scatter band fatigue data of plain and bluntly notched specimens. Based on this result, the classic stress-and the point stress-based approaches were revisited taking into account the presence of plasticity at the fatigue knee, by introducing an equivalent fully elastic material having a linear elastic strain energy density at the fatigue knee equal to that of the actual material. Accordingly, a coefficient of plasticity K p was successfully introduced to modify the classical definition of fatigue strength reduction factor, K f .

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“…Among them, the Neuber's equation [3] and Dowling's formula [4] are the representative achievements. In recent years, many scholars, based on these relational expressions, has began the researches on the mechanism of gap fatigue fracture, parameter calculation, spreading and closing of fatigue cracking [5][6][7][8] , and the SEM was used to study the fatigue crack initiation and propagation [9,10] , which provides a theoretical basis for fatigue safety design of actual structure, so that the breakage of structural components due to fatigue can be avoided thereby.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Fracture Design for Medium Carbon Steel under Extra-Low Cyclic Fatigue in Axial Loading

Tan

Duan

2008

Acta Mech. Solida Sin.

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The extra-low cyclic fracture problem of medium carbon steel under axial fatigue loading was investigated. Several problems, such as the relations of the cycle times to the depth and tip radius of the notch, loading frequency, loading range and the parameters of fracture design for medium carbon steel on condition of extra-low axial fatigue loading were discussed based on the experiments. Experimental results indicated that the tension-pressure fatigue loading mode was suitable for extra-low cyclic fatigue fracture design of medium carbon steel and it resulted in low energy consumption, fracture surface with high quality, low cycle times, and high efficiency. The appropriate parameters were as follows: loading frequency 3-5 Hz, notch tip radius r = (0.2-0.3) mm, opening angle α = 60 • , and notch depth t = (0.14-0.17)D.

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Notch effect in low cycle fatigue

Cited by 37 publications

References 8 publications

Multiaxial fatigue of V-notched steel specimens: a non-conventional application of the local energy method

Multiaxial fatigue of V-notched steel specimens: a non-conventional application of the local energy method

Strain energy-and stress-based approaches revisited in notch fatigue of ductile steels

Investigation of Fracture Design for Medium Carbon Steel under Extra-Low Cyclic Fatigue in Axial Loading

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