Determination of life under two-frequency loading. Report no. 2. Proposed method

Trufyakov, V. I.; Koval'chuk, V. S.

doi:10.1007/bf00770123

Cited by 18 publications

(25 citation statements)

References 1 publication

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“…Similarly, based on uniaxial loading and bending fatigue tests, Trufyakov and Kovalchuk [ 35 ] analyzed the effect of several metal materials under different frequencies and ratios of high and low cycle stresses on combined cycle fatigue life, which indicated that a linear relationship remains between the two-frequency loading coefficient and the ratios of high and low cycle stresses with a change in the frequency ratios and strength properties, and presented a life prediction model under two-frequency loadings as:

where

is material constant,

is the high cycle stress amplitude,

is the low cycle stress amplitude.…”

Section: Hcf-lcf Interactionmentioning

confidence: 99%

“…For the Trufyakov-Kovalchuk model, the material constant

is suggested as 1.3–1.7 for different materials. In this paper,

is 1.6 for titanium and Nickel base DZ22 alloys, while it is 1.3 for aluminum alloy, according to [ 32 , 35 ]. Figure 5 shows that the predictions by the Miner’s rule tend to be overestimated.…”

Section: Experimental Validationmentioning

confidence: 99%

“…The experimental result indicated that fatigue lives under combined variable amplitude loading were much shorter than those under constant amplitude loading. Meanwhile, various models [ 31 , 32 , 33 , 34 , 35 , 36 , 37 ] have been presented for CCF life prediction. Among them, through characterizing the effects of high cycle stress amplitude and low cycle stress amplitude on combined fatigue damage, Zheng et al [ 36 ] developed a CCF life prediction model based on the exponential decay law.…”

Section: Introductionmentioning

confidence: 99%

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A Combined High and Low Cycle Fatigue Model for Life Prediction of Turbine Blades

Zhu

Yue

et al. 2017

Materials

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Combined high and low cycle fatigue (CCF) generally induces the failure of aircraft gas turbine attachments. Based on the aero-engine load spectrum, accurate assessment of fatigue damage due to the interaction of high cycle fatigue (HCF) resulting from high frequency vibrations and low cycle fatigue (LCF) from ground-air-ground engine cycles is of critical importance for ensuring structural integrity of engine components, like turbine blades. In this paper, the influence of combined damage accumulation on the expected CCF life are investigated for turbine blades. The CCF behavior of a turbine blade is usually studied by testing with four load-controlled parameters, including high cycle stress amplitude and frequency, and low cycle stress amplitude and frequency. According to this, a new damage accumulation model is proposed based on Miner’s rule to consider the coupled damage due to HCF-LCF interaction by introducing the four load parameters. Five experimental datasets of turbine blade alloys and turbine blades were introduced for model validation and comparison between the proposed Miner, Manson-Halford, and Trufyakov-Kovalchuk models. Results show that the proposed model provides more accurate predictions than others with lower mean and standard deviation values of model prediction errors.

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where

is material constant,

is the high cycle stress amplitude,

is the low cycle stress amplitude.…”

Section: Hcf-lcf Interactionmentioning

confidence: 99%

“…For the Trufyakov-Kovalchuk model, the material constant

is suggested as 1.3–1.7 for different materials. In this paper,

Section: Experimental Validationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Combined High and Low Cycle Fatigue Model for Life Prediction of Turbine Blades

Zhu

Yue

et al. 2017

Materials

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“…According to the investigations on fatigue tests, Trufyakov and Kovalchuk (1982) developed a life prediction model by introducing a material constant c to present the effect of materials on CCF life under different cyclic frequency ratios and high and low cycle stress range ratios, as…”

Section: Existing Ccf Life Prediction Methodsmentioning

confidence: 99%

Dynamic fatigue reliability analysis of turbine blades under combined high and low cycle loadings

Yue

Zhou

et al. 2021

International Journal of Damage Mechanics

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Establishment of damage accumulation models for reflecting the combined damage mechanism on the fatigue behavior of aero-engine turbine blades is crucial for their safety. In this work, a novel combined high and low cycle fatigue (CCF) life prediction methodology is presented as a basis of that to consider the interaction between low and high cycle fatigues. Accordingly, a dynamic reliability model is proposed to study the operational reliability of turbine blades under CCF loadings. Moreover, experimental data of materials along with the collected field data from the actual turbine blades are applied to validate the CCF life prediction model and the dynamic reliability model. The validation of the results is conducted by a comparison analysis, which indicates that the proposed life prediction method yields better accuracy, while the dynamic reliability model is proved to be more in line with the outcomes derived by the Monte Carlo simulation.

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“…2) a method of calculating the decrease of the admissible number of low-cycle loadings has been experimentally validated [6,7] and is regulated by norms [1], if high-frequency cycles of change in harmonic stresses are superimposed on lowfrequency loading cycles (computational method for two-frequency loading);…”

Section: Elements Under High-frequency Random Loadingmentioning

confidence: 99%

Service-life analysis of nuclear reactor elements under high-frequency random loading

Evropin

Филатов

2013

At Energy

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Service life extension for working equipment and nominal service life extension (to 60 or more years) for nuclear reactors under construction make it even more urgent to evaluate the effect of the high-frequency component of loading (vibrations) on the long-time serviceability of structural elements. The main methodological problem of the present evaluations is to reduce the random process of vibrational loading to a harmonic form using the criterion of equivalence of fatigue damage to structural material. On the basis of experimental studies of 08Kh18N10T austenitic steel samples, an algorithm is proposed for systematizing the random process of vibrational loading to a harmonic form taking account of the slope of the fatigue curve in the high-cycle loading range.Vibrational loads, which arise unavoidably in structural elements in coolant flow as well as rotating mechanisms, can limit the nominal service life but cannot be fully taken into account at the design stage. The ASME code contains only a recommendation to minimize vibrations during setup and adjustment operations. The norms [1] recommend that at the design stage the natural frequencies of a structural element be displaced from the frequencies of forced oscillations by 30% for the first three frequencies in increasing order and by 10% for the subsequent frequencies. Since this recommendation cannot always be followed and the problem of structural vibrations in coolant flow does not always have an exact solution, the norms [1] regulate the methodological approach to taking account of the experimental vibrational loading when evaluating the fatigue strength of structures. The normative method based on the use the amplitude-frequency characteristics of a narrow- (Fig. 1a) or wide-band ( Fig. 1b) spectrum of the vibrational process [2-5] is still used today, though modern computational means for schematizing random processes make it possible to use direct methods of analyzing damage done to metal by high-frequency loading cycles.Practical experience in evaluating the effect of vibrations has been gained largely because the instrumental means for analyzing vibrational processes make it possible to obtain directly the amplitude-frequency characteristic which is used to confirm fatigue strength. However, the method used overstates the service life of structures subject to vibrations, and for the wide-band spectrum or white noise it requires conservative solutions for calculating fatigue strength (for example, the maximum amplitude of the vibrational load-maximum frequency) under conditions where the vibration process is superimposed on low-frequency cycling of the working stresses.For reactor core elements operating in the coolant flow and exposed to neutron radiation, the vibratory loading can determine their service life. Because the main structural material used in core elements is corrosion-resistant austenitic steel fatigue tests were performed on 08Kh18N10T steel under loading with two frequencies (Figs. 2, 3). The spectral parameters of high-frequency ra...

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Determination of life under two-frequency loading. Report no. 2. Proposed method

Cited by 18 publications

References 1 publication

A Combined High and Low Cycle Fatigue Model for Life Prediction of Turbine Blades

A Combined High and Low Cycle Fatigue Model for Life Prediction of Turbine Blades

Dynamic fatigue reliability analysis of turbine blades under combined high and low cycle loadings

Service-life analysis of nuclear reactor elements under high-frequency random loading

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