The effect of mean stress on the fatigue behaviour of overhead conductor function of the H/w parameter

The objective of this work is to evaluate the effects of mean stress on the fatigue behaviour of an All Aluminium Conductor (AAC Orchid), Aluminium Conductor Steel Reinforced (ACSR Tern), and an Aluminium Conductor Alloy Reinforced (ACAR 750 MCM). In this sense, 72 fatigue tests on overhead conductors were performed using different values of H/w parameter. Based on the experimental results, the parameters which describe the fatigue behaviour of the conductors were determined after generating theirs S-N curves. In the assessment of the mean stress effects on the fatigue life, Goodman and Gerber’s relations were fitted to evaluate the use of such models for the conductors. It was observed that the evaluation of the mean stress effect on the overhead conductor could be made by using the fatigue relations.

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Fatigue life prediction using multiaxial energy calculations with the mean stress effect to predict failure of linear and nonlinear elastic solids

Results in Physics ◽

10.1016/j.rinp.2016.06.007 ◽

2016 ◽

Vol 6 ◽

pp. 352-364 ◽

Cited By ~ 11

Author(s):

Marko Nagode ◽

Domen Šeruga

Keyword(s):

Fatigue Life ◽

Life Prediction ◽

Fatigue Life Prediction ◽

Stress Effect ◽

Mean Stress ◽

Elastic Solids ◽

Mean Stress Effect ◽

The Mean ◽

Linear And Nonlinear ◽

Nonlinear Elastic

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Mean Stress Effect on Fatigue Properties of Type 316 Stainless Steel: Part II — In PWR Primary Water Environment

Volume 1A: Codes and Standards ◽

10.1115/pvp2017-65136 ◽

2017 ◽

Author(s):

Masayuki Kamaya

Keyword(s):

Stainless Steel ◽

Fatigue Life ◽

Effective Strain ◽

Strain Range ◽

Stress Effect ◽

Mean Stress ◽

316 Stainless Steel ◽

Mean Stress Effect ◽

Primary Water ◽

The Mean

The mean stress effect on the fatigue life of Type 316 stainless steel was investigated at 325°C in simulated PWR primary water. It was shown that, as shown in high-temperature air environment, the fatigue life was extended by applying the mean stress under the same stress amplitude. An increase in the maximum peak stress by applying the mean stress induced additional plastic strain and this hardened the material. On the other hand, the fatigue life was shortened by the mean stress for the same strain range. The ratcheting strain caused by applying mean stress accelerated crack mouth opening and reduced fatigue life. It was also shown that the fatigue life in the simulated PWR primary water was shorter than that in air even without the mean stress. The magnitude of the reduction depended on the strain range. The reduction in fatigue life was the maximum when the strain range was 0.6%. The environmental effect disappeared when the effective strain was less than 0.4%.

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Development of New Design Fatigue Curves in Japan: Discussion of Best-Fit Curves Based on Fatigue Test Data With Small-Scale Test Specimen

Volume 3B: Design and Analysis ◽

10.1115/pvp2018-84052 ◽

2018 ◽

Cited By ~ 1

Author(s):

Yun Wang ◽

Hisamitsu Hatoh ◽

Masato Yamamoto ◽

Motoki Nakane ◽

Akihiko Hirano ◽

...

Keyword(s):

Tensile Strength ◽

Fatigue Tests ◽

Small Scale ◽

Stress Effect ◽

Mean Stress ◽

Mean Stress Effect ◽

Scale Test ◽

The Mean ◽

Best Fit ◽

Good Agreement

Based on the precedent design fatigue curves and recent fatigue data obtained from materials with different mechanical properties, new design fatigue curves with high general versatility in air have been developed by The Japan Welding Engineering Society (JWES). Structural materials with different tensile strength are utilized in fatigue tests to verify the validity of these design fatigue curves and discuss the mean stress effect. The materials employed in this study are austenitic stainless steel (SS) SUS316LTP, carbon steel (CS) STPT370, low-alloy steels (LASs) SQV2A and SCM435H, all of which are used in the structural components of nuclear power plants of Japan. The best-fit curves (BFCs) are formulated by using the parameter of tensile strength to describe the relationship between strain (stress) amplitude and fatigue life [1]. The results of fully reversed axial fatigue tests conducted with small-scale test specimens of those materials in air at ambient temperature show good agreement with the developed BFCs. The results of fatigue tests also indicate that the mean stress effect is remarkable in materials with higher tensile strength. The applicability of Modified Goodman and Smith-Watson-Topper (SWT) approaches to the design fatigue curves is compared and discussed when considering mean stress effect. The correction of mean stress effect with SWT approach shows a good agreement with the developed BFCs.

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Mean Stress Effect on Fatigue Properties of Type 316 Stainless Steel in Pressurized Water Reactors Primary Water Environment

Journal of Pressure Vessel Technology ◽

10.1115/1.4043997 ◽

2019 ◽

Vol 141 (5) ◽

Author(s):

Masayuki Kamaya

Keyword(s):

Stainless Steel ◽

Fatigue Life ◽

Water Environment ◽

Stress Effect ◽

Mean Stress ◽

Pressurized Water ◽

316 Stainless Steel ◽

Mean Stress Effect ◽

Primary Water ◽

The Mean

The mean stress effect on the fatigue life of type 316 stainless steel was investigated in simulated pressurized water reactor (PWR) primary water and air at 325 °C. The tests in air environment have revealed that the fatigue life was increased with application of the positive mean stress for the same stress amplitude because the strain range was decreased by hardening of material caused by increased maximum peak stress. On the other hand, it has been shown that the fatigue life obtained in simulated PWR primary water was decreased compared with that obtained in air environment even without the mean stress. In this study, type 316 stainless steel specimens were subjected to the fatigue test with and without application of the positive mean stress in high-temperature air and PWR water environments. First, the mean stress effect was discussed for high-temperature air environment. Then, the change in fatigue life in the PWR water environment was evaluated. It was revealed that the change in the fatigue life due to application of the mean stress in the PWR water environment could be explained in the same way as for the air environment. No additional factor was induced by applying the mean stress in the PWR water environment.

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Application of the S-N Curve Mean Stress Correction Model in Terms of Fatigue Life Estimation for Random Torsional Loading for Selected Aluminum Alloys

Materials ◽

10.3390/ma13132985 ◽

2020 ◽

Vol 13 (13) ◽

pp. 2985

Author(s):

Michał Böhm ◽

Krzysztof Kluger ◽

Sławomir Pochwała ◽

Mariusz Kupina

Keyword(s):

Fatigue Life ◽

Fatigue Strength ◽

Stress Effect ◽

Mean Stress ◽

Torsional Loading ◽

Correction Model ◽

Life Estimation ◽

Mean Stress Effect ◽

Fatigue Life Estimation ◽

The Mean

The paper presents the experimental fatigue test results for cyclic constant amplitude loading conditions for the case of the torsion of the PA4 (AW-6082-T6), PA6 (AW-2017A-T4) and PA7 (AW-2024-T3) aluminum alloy for a drilled diabolo type test specimen. The tests have been performed for the stress asymmetry ratios R = −1, R = −0.7, R = −0.5 and R = −0.3. The experimental results have been used in the process of a fatigue life estimation performed for a random generated narrowband stress signal with a zero and a non-zero global mean stress value. The calculations have been performed within the time domain with the use of the rainflow cycle counting method and the Palmgren−Miner damage hypothesis. The mean stress compensation has been performed with the S-N curve mean stress model proposed by Niesłony and Böhm. The model has been modified in terms of torsional loading conditions. In order to obtain an appropriate R = 0 ratio S-N curve fatigue strength amplitude, the Smith−Watson−Topper model was used and compared with literature fatigue strength amplitudes. The presented solution extends the use of the correction model in terms of the torsional loading condition in order to obtain new S-N curves for other R values on the basis of the R = −1 results. The work includes the computational results for new fatigue curves with and without the mean stress effect correction. The results of the computations show that the mean stress effect plays a major role in the fatigue life assessment of the tested aluminum alloys and that the method can be used to assess the fatigue life under random conditions.

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Mean Stress Effect on the Fatigue Life of 304L Austenitic Steel in Air and PWR Environments Determined with Strain- and Load-Controlled Experiments

Metals ◽

10.3390/met11020221 ◽

2021 ◽

Vol 11 (2) ◽

pp. 221 ◽

Cited By ~ 1

Author(s):

Philippe Spätig ◽

Jean-Christophe Le Roux ◽

Matthias Bruchhausen ◽

Kevin Mottershead

Keyword(s):

Fatigue Life ◽

Austenitic Steel ◽

Strain Amplitude ◽

Synergistic Effects ◽

Stress Effect ◽

Mean Stress ◽

Controlled Experiments ◽

Pressurized Water ◽

Mean Stress Effect ◽

The Mean

The mean stress effect on the fatigue life of 304L austenitic steel was evaluated at 300 °C in air and pressurized water reactor (PWR) environments. Uniaxial tests were performed in strain-control and load-control modes, with zero mean stress and a positive mean stress of 50 MPa. A specific procedure was used for the strain-controlled experiments to maintain the strain amplitude and mean stress constant. The strain-controlled data indicate that the application of positive mean stress decreases the fatigue life for a given strain amplitude in air and PWR environments. The data also show that the life reduction is independent of the environments, suggesting that no synergistic effects between the mean stress and the LWR environment occur. The load-controlled experiments confirm that the application of positive mean stress increases fatigue due to cyclic hardening processes. This observation is much less pronounced in the PWR environment. All data were analyzed using the Smith–Watson–Topper (SWT) stress–strain function, which was shown to correlate well with all strain- and load-controlled data with and without mean stress in each environment. In the SWT–life curve representation, the life reduction in the PWR environment was found fully consistent with the NUREG-CR6909 predictions.

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Mean Stress Effect on Fatigue of Welded Joint in FPSOs

Volume 3: Safety and Reliability; Materials Technology; Douglas Faulkner Symposium on Reliability and Ultimate Strength of Marine Structures ◽

10.1115/omae2006-92056 ◽

2006 ◽

Cited By ~ 1

Author(s):

Bin Zhang ◽

Torgeir Moan

Keyword(s):

Fatigue Life ◽

Fatigue Strength ◽

Residual Stresses ◽

Stress Effect ◽

Mean Stress ◽

Initial Condition ◽

Mean Stress Effect ◽

Structural Details ◽

The Mean ◽

Mean Stresses

This paper deals with the mean stress effect on the fatigue life of welded joints in FPSOs. Mean stresses in structural details of FPSOs are composed of residual stresses and mean stresses induced by external service loading conditions. Mean stresses, both the residual stresses and those induced by external load, affect on the fatigue life of structural details. Fatigue strength decreases as tensile mean stress increases. Under compressive mean stresses, fatigue lives are increased. Different fatigue analysis procedures to account for mean stress effect, i.e. JBP, JTP, DNV CN30.7 and IIW procedure, are used to compare the fatigue test data of different specimens representing different typical welded connections in ship-shaped structures from HHI in Korea. In this paper these procedures are compared and an improved procedure explicitly considering of the mean stress effect is also proposed. The fatigue strength of welded joints of FPSO is affected by the initial condition as well as possible redistribution (shake-down) of the residual stresses. The initial condition of welding residual stress and its re-distribution by static preload and cyclic load in the small scale specimens are evaluated with FE analyses and analytical equations, also compared with the test results obtained from measurement based on ordinary sectioning method.

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Modelling the mean stress effect on fatigue life of fibre reinforced plastics

International Journal of Fatigue ◽

10.1016/j.ijfatigue.2015.09.027 ◽

2016 ◽

Vol 82 ◽

pp. 689-699 ◽

Cited By ~ 10

Author(s):

D. Flore ◽

K. Wegener

Keyword(s):

Fatigue Life ◽

Stress Effect ◽

Mean Stress ◽

Reinforced Plastics ◽

Mean Stress Effect ◽

The Mean

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Mean Stress Effect on Fatigue Properties of Type 316 Stainless Steel: Part I — In High-Temperature Air Environment

Volume 1A: Codes and Standards ◽

10.1115/pvp2017-65135 ◽

2017 ◽

Author(s):

Masayuki Kamaya

Keyword(s):

Fatigue Life ◽

Stress Amplitude ◽

Mouth Opening ◽

Strain Range ◽

Peak Stress ◽

Stress Effect ◽

Mean Stress ◽

Crack Mouth ◽

Mean Stress Effect ◽

The Mean

The mean stress effect on the fatigue life of Type 316 stainless steel was investigated at 325°C in air. It was shown that the fatigue life was extended by applying the mean stress under the same stress amplitude. Increase in the maximum peak stress by applying the mean stress induced additional plastic strain and this hardened the material. The strain range of the hardened material was relatively small for the same stress amplitude, and this extended the fatigue life for a given stress amplitude. On the other hand, the fatigue life was shortened by the mean stress for the same strain range. The mean stress increased the effective strain range due to an increase in the minimum peak stress. Also, the mean stress induced ratcheting strain during the fatigue test and this accelerated crack mouth opening. The enhanced crack mouth opening accelerated the crack growth and shortened the fatigue life for a given strain range.

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