Behaviour of heat resistant power plant steels undergoing variable long term loading conditions

Granacher, J.; Scholz, Alfred; Möhlig, H.

doi:10.1002/(sici)1521-4052(200001)31:1<29::aid-mawe29>3.0.co;2-#

Cited by 7 publications

(2 citation statements)

References 10 publications

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“…However, the life of automotive components, power plants and other high-temperature facilities depends mostly on thermomechanical fatigue (TMF) [4][5][6][7]. This is because of the normally variable service conditions which contain phases of start up, full load, partial load and shutdown [4,5,8]. In addition, the influences of creep and viscoplastic stress relaxation at high temperatures need to be considered in both an accurate and efficient way [9,10].…”

Section: Introductionmentioning

confidence: 99%

Damage Operator‐Based Lifetime Calculation Under Thermomechanical Fatigue and Creep for Application on Uginox F12T EN 1.4512 Exhaust Downpipes

Nagode

Šeruga

Hack³

et al. 2011

Strain

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The article focuses on the application of a recently developed damage operator‐based lifetime calculation to a thermomechanically loaded exhaust downpipe. The damage operator approach enabling online continuous damage calculations for isothermal and non‐isothermal loading with mean stress corrections is reviewed. The article also highlights an extension of the strain‐life approach to take into account viscoplastic effects and creep. The transient results from thermal and structural analyses using finite element analyses have been applied to the exhaust downpipe in LMS Virtual.Lab and the damage predicted. Tested exhaust downpipes were then subjected to the same loading conditions as in the calculation, and load cycles were repeated up to the point of failure. Simulated and test results are comparable.

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Section: Introductionmentioning

confidence: 99%

Damage Operator‐Based Lifetime Calculation Under Thermomechanical Fatigue and Creep for Application on Uginox F12T EN 1.4512 Exhaust Downpipes

Nagode

Šeruga

Hack³

et al. 2011

Strain

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“…This is due to the normally variable service conditions, which contain phases of startup, full load, partial load and shut-down. 1 The failure mechanisms associated with TMF are mechanical fatigue, oxidation and creep. There is also a variety of secondary order effects, like ageing and phase transformations 2 that are difficult to take into account.…”

Section: Introductionmentioning

confidence: 99%

Coupled elastoplasticity and viscoplasticity under thermomechanical loading

Nagode

Fajdiga

2007

Fatigue Fract Eng Mat Struct

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A B S T R A C T This paper is a contribution to material behaviour modelling. Total strain is decomposed into elastoplastic and viscoplastic strains. Both parts are analysed separately and put together by the principle of superposition. The spring-slider model controlled by either stress or strain enables elastoplasticity modelling under constant or variable temperature with the Prandtl operators. Viscoplasticity is taken into account, if temperature exceeds creep temperature, by adding a nonlinear damper to existing spring-slider models, otherwise just elastoplasticity is considered. The material parameters result from isothermal strain-controlled low cycle fatigue (LCF) tests. Hysteresis loops are assumed to be stabilized. The high speed of computation that is characteristic of Masing and memory rules is retained. Solving of differential equations is not required. The model developed so far is uniaxial, but a multiaxial extension is possible. N O M E N C L A T U R EYoung's modulus i = data point index j = the play operator index k = temperature index, elastic limit K = temperature dependent material parameter K = cyclic hardening coefficient N = temperature dependent material parameter n = cyclic hardening exponent n q = index of the top fictive yield strain n r = index of the top yield stress n T = index of the top temperature nε = index of the top strain rate n σ = index of the top stress q j = fictive yield strain r j = yield stress t = time T = temperature T c = creep temperature α j = the Prandtl densityCorrespondence: M. Nagode.

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Deformation and life assessment of high temperature materials under creep fatigue loading

Scholz¹,

Berger

2005

Materialwissenschaft Werkst

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The knowledge of mechanical long term behaviour under static and cyclic loading for high temperature components requires methodologies for life assessment in order to employ the full potential of materials. A phenomenological life time prediction concept which was developed for multi-stage creep fatigue loading demonstrates the applicability of rules for synthesis of stress strain path and relaxation including an internal stress concept, as well as mean stress effects. Further, a creep fatigue interaction concept which was also developed covers a wide range of creep dominant loading as well as fatigue dominant loading.Service-type experiments conducted at different strain rates and hold times for verification purposes demonstrate the acceptability of life prediction method for variation of conventional 1 %Cr-steels as well as modern high chromium 9-10 %Cr-steels.Generally, the service life of components is influenced by multiaxial behaviour. Multi-axial experiments with e.g. notched specimens and with cruciform specimens accompanied by advanced methods for calculation of stress strain path and life time prediction stress conditions are of future interest.

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Behaviour of heat resistant power plant steels undergoing variable long term loading conditions

Cited by 7 publications

References 10 publications

Damage Operator‐Based Lifetime Calculation Under Thermomechanical Fatigue and Creep for Application on Uginox F12T EN 1.4512 Exhaust Downpipes

Damage Operator‐Based Lifetime Calculation Under Thermomechanical Fatigue and Creep for Application on Uginox F12T EN 1.4512 Exhaust Downpipes

Coupled elastoplasticity and viscoplasticity under thermomechanical loading

Deformation and life assessment of high temperature materials under creep fatigue loading

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