The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Masayuki Kamaya - One of the best experts on this subject based on the ideXlab platform.
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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, 2019Co-Authors: Masayuki KamayaAbstract: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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Mean Stress Effect on Fatigue Properties of Type 316 Stainless Steel: Part I — In High-Temperature Air Environment
Volume 1A: Codes and Standards, 2017Co-Authors: Masayuki KamayaAbstract: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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Mean Stress Effect on Fatigue Properties of Type 316 Stainless Steel: Part II — In PWR Primary Water Environment
Volume 1A: Codes and Standards, 2017Co-Authors: Masayuki KamayaAbstract: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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Mean Stress Effect on fatigue strength of stainless steel
International Journal of Fatigue, 2015Co-Authors: Masayuki Kamaya, Masahiro KawakuboAbstract:Abstract Influence of Mean Stress on fatigue life and fatigue limit was investigated for Type 316 stainless steel. The results for prestrained specimens revealed that fatigue life was almost the same in the same strain range regardless of Stress amplitude, maximum peak Stress and Mean strain. The fatigue life was shortened when applying the Mean Stress for the same strain range, whereas it was increased for the same Stress amplitude. It was shown that the reduction in fatigue life was brought about by the change in the Effective strain range, which was caused by the increase in minimum peak Stress and the ratcheting strain. The fatigue life could be predicted conservatively even if the Mean strain was applied by assuming the Effective strain range to be equal to the total strain range (by assuming the crack mouth to be never closed). It was concluded that the Mean Stress correction was not necessary for the load-controlled cyclic loading and for the region where the ratcheting strain was constrained.
José Alexander Araújo - One of the best experts on this subject based on the ideXlab platform.
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Issues on the Mean Stress Effect in fretting fatigue of a 7050-T7451 Al alloy posed by new experimental data
International Journal of Fatigue, 2009Co-Authors: Luciana Sgarbi Rossino, F.c. Castro, W.w. Bose Filho, José Alexander AraújoAbstract:The aims of this work are: (i) to produce new experimental data for fretting fatigue considering the presence of a Mean bulk Stress and (ii) to assess two design methodologies against failure by fretting fatigue. Tests on a cylinder–flat contact configuration were conducted using a fretting apparatus mounted on a servo-hydraulic machine. The material used for both the pads and fatigue specimen was an aeronautical 7050-T7451 Al alloy. The experimental program was designed with all relevant parameters, apart from the Mean bulk load (always applied before the contact loads), kept constant. The Mean bulk Stress varied from compressive to tensile values while maintaining a high peak pressure in order to encourage crack initiation. Two methodologies against fretting fatigue are proposed and confronted against the experimental data. The non-local Stress-based methodology considers the evaluation of a critical plane fatigue criterion at the center of a process zone located beneath the contacting surfaces. The results showed that it correctly predicts crack initiation, but was not capable to provide successful prediction of the integrity of the specimens. Alternatively, we considered a crack arrest criterion which has the potential to provide a more complete description about the integrity of the specimens.CNPqCAPE
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Issues on the Mean Stress Effect in fretting fatigue of a 7050-T7451 Al alloy posed by new experimental data
International Journal of Fatigue, 2008Co-Authors: Luciana Sgarbi Rossino, F.c. Castro, W. W. Bose Filho, José Alexander AraújoAbstract:Abstract The aims of this work are: (i) to produce new experimental data for fretting fatigue considering the presence of a Mean bulk Stress and (ii) to assess two design methodologies against failure by fretting fatigue. Tests on a cylinder–flat contact configuration were conducted using a fretting apparatus mounted on a servo-hydraulic machine. The material used for both the pads and fatigue specimen was an aeronautical 7050-T7451 Al alloy. The experimental program was designed with all relevant parameters, apart from the Mean bulk load (always applied before the contact loads), kept constant. The Mean bulk Stress varied from compressive to tensile values while maintaining a high peak pressure in order to encourage crack initiation. Two methodologies against fretting fatigue are proposed and confronted against the experimental data. The non-local Stress-based methodology considers the evaluation of a critical plane fatigue criterion at the center of a process zone located beneath the contacting surfaces. The results showed that it correctly predicts crack initiation, but was not capable to provide successful prediction of the integrity of the specimens. Alternatively, we considered a crack arrest criterion which has the potential to provide a more complete description about the integrity of the specimens.
Naoki Osawa - One of the best experts on this subject based on the ideXlab platform.
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Fatigue life prediction for 9%Ni steel butt welded joints
International Journal of Fatigue, 2021Co-Authors: Toru Shiratsuchi, Naoki OsawaAbstract:Abstract This study proposed the fatigue life prediction method for welded joints which is considered the geometric Effect, the difference of cyclic Stress–strain properties between parent material, the HAZ, and weld metal, and the Mean Stress Effect by welding residual Stress and fatigue loading. The proposed prediction method consists of the finiteelement analyses, which are the welding simulation and the nonlinear structural analysis applied fatigue loading, and the estimation method of the fatigue crack initiation and the fatigue crack propagation. The proposed method indicated as being able to successfully predict the fatigue life for 9% Ni steel butt welded joints.
Michał Böhm - One of the best experts on this subject based on the ideXlab platform.
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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 (Basel Switzerland), 2020Co-Authors: Michał Böhm, Krzysztof Kluger, Sławomir Pochwała, Mariusz KupinaAbstract: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 Nieslony and Bohm. 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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Fatigue Life Estimation with Mean Stress Effect Compensation for Lightweight Structures-The Case of GLARE 2 Composite.
Polymers, 2020Co-Authors: Michał Böhm, Karolina GłowackaAbstract:This paper describes the current state-of-the-art in fatigue life assessment for lightweight composite structures with the use of the frequency domain fatigue life calculation method. Random stationary gaussian loading signals have been generated and served in the process of fatigue calculation. The material information that is being used in the calculation process has been obtained from literature for the Glare 2 composite. The Effect of nonzero Mean Stress and different fiber orientations have been taken into account. The calculations have been performed for two Mean Stress compensation models by Goodman and Gerber. The proposed procedure gives satisfying results for the high-cycle fatigue region for Goodman and an overall good comparison in both regimes for the Gerber model.
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Universal Method for Applying the Mean-Stress Effect Correction in Stochastic Fatigue-Damage Accumulation
Materials Performance and Characterization, 2016Co-Authors: Adam Niesłony, Michał BöhmAbstract:Most of the models used for taking into account the influence of Mean Stress on fatigue life work on the basis of the correction of Stress amplitudes of particular loading cycles. This can be done directly on the amplitudes or through the modification of the reference S–N curve. The mentioned procedure is also applicable for variable amplitude loading where, after rainflow cycle counting, all loading cycles described by amplitude and Mean-Stress value are designated. Mean-Stress correction can be difficult to apply in stochastic fatigue-damage accumulation, also called the spectral method, where the load and the Stress level is defined in the frequency domain using the appropriate power spectral density (PSD) function. The PSD function by itself does not give information to the user about the level of Mean Stress and only provides us with some statistical information of the fluctuating part of the random loading processes. The aim of the paper is to present how we can perform the Mean-Stress Effect correction directly on a PSD function of Stress using well-known models, such as proposed by Gerber, Goodman, Soderberg, or Morrow. The correction can be performed depending on the frequency component, which is a significant advantage of the presented method. The theoretical elaborations were used to develop a computer simulation used to compare the frequency-domain with the time-domain computation path. To show the Effectiveness of the presented method, fatigue life has been estimated and compared with experimental fatigue test results for S355JR steel.
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Mean Stress Effect correction using constant Stress ratio S–N curves
International Journal of Fatigue, 2013Co-Authors: Adam Niesłony, Michał BöhmAbstract:Abstract This paper presents a Stress based approach to take into account the influence of the Mean Stress value on fatigue strength of constructional materials. Elaborated model uses two S–N curves, i.e. for alternating Stress (R = −1) and another one obtained under Stress ratio R ≠ −1, for calibrating the equations of boundary condition. Two particular equations for the coefficient of intensification in Stress transformations were proposed. The main advantage of the proposed solution is that the Mean Stress Effect correction depends on the number of cycles to failure, what corresponds to the observed changes in experimental results presented in the literature. Proposed relations were compared with popular models for Mean Stress correction. The verification was made using selected series of experimental results taken from the literature. It was shown that the proposed solution is well correlated with experimental results.
Michal Bohm - One of the best experts on this subject based on the ideXlab platform.
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frequency domain fatigue life estimation with Mean Stress correction
International Journal of Fatigue, 2016Co-Authors: Adam Nieslony, Michal BohmAbstract:Abstract Two frequency-domain fatigue life calculation methods are presented which take into account the impact of the Mean Stress Effect. The emphasis is set on the algorithm for fatigue life assessment of the method proposed by the authors. It is supplemented with a Mean Stress Effect correction. Correction method is based on the direct transformation of the zero Mean Stress Power Spectral Density (PSD) due to Mean Stress. The method is verified on the basis of own results for the S355JR steel. The authors analyze five models for the designation of the probability density function used in the calculation process. The results are presented in the form of probability distributions after PSD transformation and the calculated fatigue life is being compared with the experimental life in fatigue comparison graphs. An analysis of the choice of a Mean Stress correction model is also widely discussed and a fatigue life estimation is also performed. The method proposed by the authors is being compared with the Kihl–Sarkani method for Mean Stress correction in frequency domain.
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Mean Stress Effect correction in frequency domain methods for fatigue life assessment
Procedia Engineering, 2015Co-Authors: Adam Nieslony, Michal BohmAbstract:Abstract Two fatigue life calculation methods are presented. One defined in the time domain and the second one defined in the frequency domain – both supplemented with a Mean Stress Effect correction. The method is verified on the basis of own results for the S355JR steel. The authors analyze six models for the designation of the probability density function (PDF) of Stress amplitudes used in the calculation process. The results are presented in the form of probability distributions before and after PSD transformation and the calculated fatigue life's are being compared with the experimental ones in fatigue comparison graphs.
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Mean Stress Effect correction using constant Stress ratio s n curves
International Journal of Fatigue, 2013Co-Authors: Adam Nieslony, Michal BohmAbstract:Abstract This paper presents a Stress based approach to take into account the influence of the Mean Stress value on fatigue strength of constructional materials. Elaborated model uses two S–N curves, i.e. for alternating Stress (R = −1) and another one obtained under Stress ratio R ≠ −1, for calibrating the equations of boundary condition. Two particular equations for the coefficient of intensification in Stress transformations were proposed. The main advantage of the proposed solution is that the Mean Stress Effect correction depends on the number of cycles to failure, what corresponds to the observed changes in experimental results presented in the literature. Proposed relations were compared with popular models for Mean Stress correction. The verification was made using selected series of experimental results taken from the literature. It was shown that the proposed solution is well correlated with experimental results.