Crack initiation and propagation in torsional fatigue of circumferentially notched steel bars

Tanaka, Keisuke

doi:10.1016/j.ijfatigue.2013.01.002

Cited by 30 publications

(19 citation statements)

References 22 publications

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“…at a relative potential drop increase V/V 0 equal to 1.01. Such operational definition is consistent with that adopted by Tanaka [6]. According to the zoom reported in Fig.…”

Section: Calibration Curves Of the Potential Drop Methodssupporting

confidence: 87%

“…This notch-strengthening effect has been observed by fatigue testing cylindrical specimens made of austenitic stainless steels [1][2][3], NiCrMo steel [4], pure titanium [5], but it was not found in carbon steels [3,7,8]. As recently discussed by Tanaka [6], this effect can be explained on the basis of different morphologies of the fracture surfaces: in circumferentially notched bars under torsion fatigue loadings, factory-roof type fracture surfaces have been found; consequently, the sliding contact and the meshing between crack surfaces cause the retardation of crack propagation [9][10][11][12][13]. In this context, the fatigue behaviour of circumferentially notched specimens made of titanium grade 5 alloy, Ti-6Al-4V, has been analysed in the present contribution.…”

Section: Introductionmentioning

confidence: 79%

“…n the recent literature [1][2][3][4][5][6], an unexpected notch-strengthening phenomenon was found in circumferentially notched specimens under pure torsion or combined tension-torsion multiaxial fatigue loadings. The fatigue life of notched bars resulted longer than that of smooth ones, the higher the stress concentration factor under the same load amplitude.…”

Section: Introductionmentioning

confidence: 99%

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Crack initiation life in notched Ti-6Al-4V titanium bars under uniaxial and multiaxial fatigue: synthesis based on the averaged strain energy density approach

Meneghetti¹,

Campagnolo²,

Berto³

et al. 2017

Frattura Ed Integrità Strutturale

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ABSTRACT. The fatigue behaviour of circumferentially notched specimens made of titanium alloy, Ti-6Al-4V, has been analysed. To investigate the notch effect on the fatigue strength, pure bending, pure torsion and multiaxial bending-torsion fatigue tests have been carried out on specimens characterized by two different root radii, namely 0.1 and 4 mm. Crack nucleation and subsequent propagation have been accurately monitored by using the direct current potential drop (DCPD) technique. Based on the results obtained from the potential drop technique, the crack initiation life has been defined in correspondence of a relative potential drop increase V/V0 equal to 1%, and it has been used as failure criterion. Doing so, the effect of extrinsic mechanisms operating during crack propagation phase, such as sliding contact, friction and meshing between fracture surfaces, is expected to be reduced. The experimental fatigue test results have been re-analysed by using the local strain energy density (SED) averaged over a structural volume having radius R0 and surrounding the notch tip. Finally, the use of the local strain energy density parameter allowed us to properly correlate the crack initiation life of Ti-6Al-4V notched specimens, despite the different notch geometries and loading conditions involved in the tests.

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“…at a relative potential drop increase V/V 0 equal to 1.01. Such operational definition is consistent with that adopted by Tanaka [6]. According to the zoom reported in Fig.…”

Section: Calibration Curves Of the Potential Drop Methodssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Crack initiation life in notched Ti-6Al-4V titanium bars under uniaxial and multiaxial fatigue: synthesis based on the averaged strain energy density approach

Meneghetti¹,

Campagnolo²,

Berto³

et al. 2017

Frattura Ed Integrità Strutturale

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“…3 Top view of crack with crack front passing through many grains [1] principal stress. This is also true for a cylindrical bar loaded by a cyclic torsion load, see Interesting observations were recently published by Tanaka [6]. He carried out fatigue tests on specimens with a blunt notch and a sharp notch, see Fig.…”

Section: Different Modes Of Fatigue Crack Growthmentioning

confidence: 65%

Biaxial Fatigue of Metals

Schijve¹

2016

SpringerBriefs in Applied Sciences and Technology

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“…In some studies (Tanaka, 2012;2013) circumferentially notched bars (of austenitic stainless steel, SUS316L and carbon steel, SGV410, with three different notch-tip radii) were fatigued under cyclic torsion without and with static tension.…”

Section: Description Of the Fatigue Of A Metal Partmentioning

confidence: 99%

Multiaxial Fatigue Strength to Notched specimens made of 40CrMoV13.9

Berto¹,

Gagani²,

Aversa³

et al. 2016

American Journal of Engineering and Applied Sciences

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Fatigue is a process (succession of mechanisms) which under the action of time-varying strains or deformations modifies the local properties of a material. These can lead to the formation of cracks and eventual rupture of the structure. Fatigue is in particular characterized by an extent of variation in stress which may be well below the yield strength of the material. The main stages of fatigue failure of an assembly are the initiation of cracks (if defects are not already present in the material), the propagation of cracks and the final rupture. The parameters often used to predict the fatigue behavior and thus the number of cycles at break of a structure is: The amplitude of the stress (loading or imposed strain), its average value, the surface state and the medium In which the structure will be used. Even if the study of fatigue is based on theoretical considerations (in particular the mechanics of the rupture), it is essentially an experimental field. The characterization of a material, a part, an assembly, a structure, requires numerous tests and measurements. The work deals with multiaxial fatigue power of specimens which are notched and all made of 40CrMoV13.9. Circumferentially V-notched specimens and semicircular notched were tested under combined tension and torsion loading, both, in phase or out of phase. Geometry of symmetric axis of V notched issues has been characterized of a notch radius constant from (1 mm) and V-notch opening angle of 90°. The semicircular specimens were characterized by a constant notch tip radius. For both situations the net diameter sectional area was 12 mm. The results from multi-axial tests are discussed together with those obtained being all under loading pure torsion and tension by the issues notched having the same geometry. Altogether more than 120 new fatigue data are summarized in the present work. All presented fatigue data are first in terms of nominal amplitudes stress and then reanalyzed in terms of the mean value of the strain energy density evaluated over a finite size semicircular sector surrounding the tip of the notch.

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Crack initiation and propagation in torsional fatigue of circumferentially notched steel bars

Cited by 30 publications

References 22 publications

Crack initiation life in notched Ti-6Al-4V titanium bars under uniaxial and multiaxial fatigue: synthesis based on the averaged strain energy density approach

Crack initiation life in notched Ti-6Al-4V titanium bars under uniaxial and multiaxial fatigue: synthesis based on the averaged strain energy density approach

Biaxial Fatigue of Metals

Multiaxial Fatigue Strength to Notched specimens made of 40CrMoV13.9

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