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dc.contributor.authorShenoy, Mahesh M.en_US
dc.date.accessioned2006-09-01T19:27:16Z
dc.date.available2006-09-01T19:27:16Z
dc.date.issued2006-06-01en_US
dc.identifier.urihttp://hdl.handle.net/1853/11515
dc.description.abstractMicrostructural features at different scales affect the constitutive stress-strain response and the fatigue crack initiation life in Ni-base superalloys. While numerous efforts have been made in the past to experimentally characterize the effects of these features on the stress-strain response and/or the crack initiation life, there is a significant variability in the data with sometimes contradictory conclusions, in addition to the substantial costs involved in experimental testing. Computational techniques can be useful tools to better understand these effects since they are relatively inexpensive and are not restricted by the limitations in processing techniques. The effect of microstructure on the stress-strain response and the variability in fatigue life were analyzed using two Ni-base superalloys; DS GTD111 which is a directionally solidified Ni-base superalloy, and IN100 which is a polycrystalline Ni-base superalloy. Physically-based constitutive models were formulated and implemented as user material subroutines in ABAQUS using the single crystal plasticity framework which can predict the material stress-strain response with the microstructure-dependence embedded into them. The model parameters were calibrated using experimental cyclic stress-strain histories. A computational exercise was employed to quantify the influence of idealized microstructural variables on the fatigue crack initiation life. Understanding was sought regarding the most significant microstructure features using explicit modeling of the microstructure with the aim to predict the variability in fatigue crack initiation life and to guide material design for fatigue resistant microstructures. Lastly, it is noted that crystal plasticity models are often too computationally intensive if the objective is to model the macroscopic behavior of a textured or randomly oriented 3-D polycrystal in an engineering component. Homogenized constitutive models were formulated and implemented as user material subroutines in ABAQUS, which can capture the macroscale stress-strain response in both DS GTD111 and IN100. Even though the study was conducted on two specific Ni-base superalloys; DS GTD111 and IN100, the objective was to develop generic frameworks which should also be applicable to other alloy systems.en_US
dc.format.extent8718311 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.publisherGeorgia Institute of Technologyen_US
dc.subjectNickelen_US
dc.subjectConstitutive modeling
dc.subjectLife prediction
dc.subjectFatigue
dc.subjectCreep
dc.subjectThermomechanical
dc.subject.lcshNickel alloys Thermomechanical propertiesen_US
dc.subject.lcshHeat resistant alloys Creepen_US
dc.subject.lcshHeat resistant alloys Fatigueen_US
dc.subject.lcshMicrostructureen_US
dc.titleConstitutive Modeling and Life Prediction in Ni-Base Superalloysen_US
dc.typeDissertationen_US
dc.description.degreePh.D.en_US
dc.contributor.departmentMechanical Engineeringen_US
dc.description.advisorCommittee Chair: David, McDowell; Committee Co-Chair: Neu, Richard; Committee Member: Sanders, Thomas; Committee Member: Thadani, Naresh; Committee Member: Zhou, Minen_US


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