A mechanism-based approach from low cycle fatigue to thermomechanical fatigue life prediction

DOIResolve DOI: http://doi.org/10.1115/GT2015-43974
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Proceedings titleProceedings of the ASME Turbo Expo
ConferenceASME Turbo Expo 2015: Turbine Technical Conference and Exposition, GT 2015, 15 June 2015 through 19 June 2015
SubjectCast iron; Constitutive equations; Creep; Deformation; Fatigue of materials; Gas turbines; Stress-strain curves; Turbines; Cyclic stress strain curves; Diffusion mechanisms; Intergranular embrittlement; Isothermal low cycle fatigues; Rate-independent plasticities; Thermo mechanical fatigues (TMF); Fatigue damage
AbstractDeformation and damage accumulation occur by fundamental dislocation and diffusion mechanisms. An integrated creep-fatigue theory (ICFT) has been developed, based on the physical strain decomposition rule that recognizes the role of each deformation mechanism and thus relate damage accumulation to its underlying physical mechanism(s). The ICFT formulates the overall damage accumulation as a holistic damage process consisting of nucleation and propagation of surface/subsurface cracks in coalescence with internally distributed damage/ discontinuities. These guiding principles run through both isothermal low cycle fatigue (LCF) and thermomechanical fatigue (TMF) under general conditions. This paper presents a methodology using mechanismbased constitutive equations to describe the cyclic stress strain curve and the non-linear damage accumulation equation incorporating i) rate-independent plasticity-induced fatigue, ii) intergranular embrittlement, iii) creep and iv) oxidation to predict LCF and TMF lives of ductile cast iron (DCI). The complication of the mechanisms and their interactions in this material provide a good demonstration case for the model, which is in good agreement with the experimental observations.
Publication date
PublisherAmerican Society of Mechanical Engineers
AffiliationNational Research Council Canada; Aerospace
Peer reviewedYes
NPARC number21277415
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Record identifierfdf21166-343b-434f-9207-a98836dcc84b
Record created2016-03-09
Record modified2016-05-09
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