A lifing method based on R5 and viscoplasticity modelling and its application to turbine rotor under thermomechanical loading. (March 2020)

• Record Type: Journal Article
• Authors: Bonetti, R.; Hadjipakkos, P.; Rae, Y.; Hughes, J.; Sun, W.
• Is Part Of: Engineering failure analysis. Volume 110(2020)
• Publication Date: 2020-03
• Subjects: Life assessment -- R5 -- Viscoplasticity -- Turbine rotors -- FV566; System failures (Engineering) -- Periodicals; Fracture mechanics -- Periodicals; Reliability (Engineering) -- Periodicals; Pannes -- Périodiques; Rupture, Mécanique de la -- Périodiques; Fiabilité -- Périodiques; Fracture mechanics; Reliability (Engineering); System failures (Engineering); Periodicals; Electronic journals; 620.112
• DOI: 10.1016/j.engfailanal.2020.104416
• Languages: English
• ISSNs: 1350-6307

Abstract

Highlights: An integrated life assessment framework for structures under thermomechanical loadings is proposed. The framework is based on R5 and viscoplasticity modelling. The procedure is implemented on an industrial gas turbine. Abstract: An integrated life assessment procedure for structures operating under thermomechanical loading has been developed. The methodology uses a viscoplasticity based framework combined with the R5 life assessment code. The viscoplastic constitutive model used for the stress-strain analysis is derived from the Chaboche-Lemaitre formulation that allows to directly obtain the required parameters for the R5 assessment as stress relaxation per cycle and the elastic follow-up factor. The R5 procedure is therefore significantly simplified. The proposed life assessment procedure is demonstrated on a martensitic steel (FV566) industrial gas turbine rotor under a typical start up – shut down operation. The effect of creep-fatigue interaction at different locations within the rotor structure is assessed and the remaining life at each location is calculated. A sensitivity study is performed at half load, which shows an increase in lifetime of the rotor.