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

2016 ◽  
Vol 6 ◽  
pp. 352-364 ◽  
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

scholarly journals Fatigue Life Prediction of Rolling Bearings Based on Modified SWT Mean Stress Correction

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Aodi Yu ◽  
Hong-Zhong Huang ◽  
Yan-Feng Li ◽  
He Li ◽  
Ying Zeng
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Sensitivity Coefficient ◽  
Fatigue Life Prediction ◽  
Stress Effect ◽  
Mean Stress ◽  
Rolling Bearings ◽  
Contact Loads ◽  
Compensation Factor ◽  
The Mean

AbstractThe existing engineering empirical life analysis models are not capable of considering the constitutive behavior of materials under contact loads; as a consequence, these methods may not be accurate to predict fatigue lives of rolling bearings. In addition, the contact stress of bearing in operation is cyclically pulsating, it also means that the bearing undergo non-symmetrical fatigue loadings. Since the mean stress has great effects on fatigue life, in this work, a novel fatigue life prediction model based on the modified SWT mean stress correction is proposed as a basis of which to estimate the fatigue life of rolling bearings, in which, takes sensitivity of materials and mean stress into account. A compensation factor is introduced to overcome the inaccurate predictions resulted from the Smith, Watson, and Topper (SWT) model that considers the mean stress effect and sensitivity while assuming the sensitivity coefficient of all materials to be 0.5. Moreover, the validation of the model is finalized by several practical experimental data and the comparison to the conventional SWT model. The results show the better performance of the proposed model, especially in the accuracy than the existing SWT model. This research will shed light on a new direction for predicting the fatigue life of rolling bearings.

Mean stress effect correction in strain energy-based fatigue life prediction of metals

2016 ◽  
Vol 26 (8) ◽  
pp. 1219-1241 ◽  
Author(s):  
Shun-Peng Zhu ◽  
Qiang Lei ◽  
Hong-Zhong Huang ◽  
Yuan-Jian Yang ◽  
Weiwen Peng
Keyword(s):  
Fatigue Life ◽  
Strain Energy ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Stress Effect ◽  
Mean Stress ◽  
Mean Stress Effect

scholarly journals A Modified Walker Model Dealing with Mean Stress Effect in Fatigue Life Prediction for Aeroengine Disks

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Shan Lu ◽  
Yunlai Su ◽  
Mao Yang ◽  
Yan Li
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Maximum Stress ◽  
Fatigue Life Prediction ◽  
Stress Effect ◽  
Mean Stress ◽  
Mean Stress Effect ◽  
Proposed Model ◽  
Smooth Bars ◽  
Turbine Disks

Mean stress effect plays an important role in fatigue life prediction, and it is discovered that maximum stress has nonnegligible influence on mean stress effect. Therefore, a modified Walker model is proposed to account for mean stress effect on fatigue life of aeroengine disks, which contains the influence of stress ratio and maximum stress on mean stress effect. Eight sets of fatigue data for standard smooth bars from six kinds of materials commonly used in aeroengine disks as well as two sets of experimental data from simulated specimens of turbine disks were employed to investigate the prediction capability of the proposed model against other candidate mean stress relationships. It is found that Goodman model generates most conservative results, while Morrow model overestimates fatigue life for most cases. SWT model yields similar results to Walker model but with less accuracy. The results of the modified Walker model turn out to be superior to those of any other candidate models for all cases examined, especially for large mean stress ones. Thus, the modified Walker model can be an effective method to predict fatigue lives of aeroengine disks influenced by mean stresses.

Fatigue-life prediction under irregular stress conditions

1970 ◽  
Vol 5 (3) ◽  
pp. 207-211 ◽  
Author(s):  
T H Erismann
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Stress Conditions ◽  
Fatigue Life Prediction ◽  
Mean Stress ◽  
Arbitrary Loading ◽  
Empirical Determination ◽  
The Mean ◽  
Standard Tests

The present work is a shorter version of a more detailed treatise by the author (1)∗. The method consists of two parts: the empirical determination of certain characteristics of a material by means of a relatively small number of well defined standard tests, and the arithmetical application of the results obtained to arbitrary loading histories. The following groups of parameters are thus taken into account: the variations of the mean stress; the interaction of these variations and the superposed oscillating stresses; the spectrum of the oscillating-stress amplitudes; the sequence of the oscillating-stress amplitudes.

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

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%.

FATIGUE LIFE PREDICTION OF ROLLED AZ31 MAGNESIUM ALLOY USING AN ENERGY-BASED MODEL

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5503-5508 ◽  
Author(s):  
SUNG HYUK PARK ◽  
SEONG-GU HONG ◽  
BYOUNG HO LEE ◽  
CHONG SOO LEE
Keyword(s):  
Fatigue Life ◽  
Magnesium Alloy ◽  
Deformation Behavior ◽  
Strain Energy ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Az31 Magnesium Alloy ◽  
Stress And Strain ◽  
Mean Stress ◽  
The Mean

Fatigue behavior of rolled AZ31 magnesium alloy, which shows an anisotropic deformation behavior due to the direction dependent formation of deformation twins, was investigated by carrying out stress and strain controlled fatigue tests. The anisotropy in deformation behavior introduced asymmetric stress-strain hysteresis hoops, which make it difficult to use common fatigue life prediction models, such as stress and strain-based models, and induced mean stress and/or strain even under fully-reversed conditions; the tensile mean stress and strain were found to have a harmful effect on the fatigue resistance. An energy-based model was used to describe the fatigue life behavior as strain energy density was stabilized at the early stage of fatigue life and nearly invariant through entire life. To account for the mean stress and strain effects, an elastic energy related to the mean stress and a plastic strain energy consumed by the mean strain were appropriately considered in the model. The results showed that there is good agreement between the prediction and the experimental data.

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

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.

scholarly journals 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 ◽  
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.

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

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 221 ◽  
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.

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

2018 ◽  
Vol 165 ◽  
pp. 11001
Author(s):  
Remy Badibanga ◽  
Thiago Miranda ◽  
Pedro Rocha ◽  
Jorge Ferreira ◽  
Cosme da Silva ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Experimental Results ◽  
Stress Effect ◽  
Mean Stress ◽  
Stress Effects ◽  
Mean Stress Effect ◽  
The Mean

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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