Identification of constants of a viscoplastic constitutive model for a single crystal alloy

Kunkel, Robert; Kollmann, Franz

doi:10.1007/bf01213016

Cited by 11 publications

(5 citation statements)

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“…The Thermomechanical efficiency of gas turbines is dependent on the temperature at which the turbine operates. A high firing temperature leads to a dual benefit, an increase in specific work (that is the output per unit of air flow), and a reduction in fuel consumption [14][15][16][17]. These severe operation conditions produce multiple deformation mechanisms, which are applied to the turbine components such as the combustors, transition pieces, exhaust, and turbine blades [13,18] illustrated in Figure 5.…”

Section: List Of Tablesmentioning

confidence: 99%

“…Moreover, by knowing the behavior of the material the operational temperature might be increased for better system efficiencies. On the other hand, a better understanding of the material behavior leads to less conservative designs which in return reduce the cost of hardware and components, since the material is effectively used[15][16][17]39]. There has been considerable effort to develop unified constitutive models capable of describing the inelastic behavior of Hastelloy X and stainless steel 304.…”

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confidence: 99%

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Development of a Novel Hybrid Unified Viscoplastic Constitutive Model

Stewart

2015

Volume 9: Mechanics of Solids, Structures and Fluids

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2015Dedicado a mi familia, a los de aquí y a los que desde arriba siguen aquí. v ACKNOWLEDGEMENTS I would like to thank my advisor Dr. Calvin M. Stewart, whose guidance and advice was fundamental to complete my master degree. It has been an honor to work and learn from such a professional advisor. I want to state my gratitude to the Mechanical Engineering Department for all the opportunities that have been provided to me which have tremendously contributed to my professional career. Finally I would like to thank my family for being my inspiration and for all the provided support. vi ABSTRACT Gas turbines are now days used in power plants for power generation and for propulsion in the aerospace industry. In these applications gas turbines are exposed to severe temperature and pressure variations during operating cycles. These severe operating conditions exposed the turbine's components to multiple deformation mechanisms which degrade the material and eventually lead to failure of the components. Nickel based and austenitic super alloys are candidate material used for these applications due to its high strength and corrosion resistance at elevated temperatures. At such temperature levels, candidate materials exhibit a rate-dependent or viscoplastic behavior which difficult the prediction or description of the material response due to deformation mechanisms. Unified viscoplastic constitutive models are used to describe this viscoplastic behavior of materials. In the present work Miller and Walker unified viscoplastic models are presented, described and exercised to model the creep of Hastelloy X and the low cycle fatigue behavior of stainless steel 304. The numerical simulation results are compared to an extensive database of experimental data to fully validate the capabilities and limitations of the considered models. Material constant heuristic optimizer (MACHO) software is explained and used to determine both models material constants and ensure a systematic calculation of them.This software uses the simulated annealing algorithm to determine the optimal material constants values in a global surface, by comparing numerical simulations to an extensive database of experimental data. A quantitative analysis on the performance of both models is conducted to determine the most suitable model to predict material's behavior. Based on the two exercised classical viscoplastic models, a novel hybrid unified model is introduced, to accurately describe the inelastic behavior caused by creep and fatigue effects at high temperature. The presented

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Section: List Of Tablesmentioning

confidence: 99%

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confidence: 99%

Development of a Novel Hybrid Unified Viscoplastic Constitutive Model

Stewart

2015

Volume 9: Mechanics of Solids, Structures and Fluids

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“…More research about parameter identification can be found e.g. in Mahnken and Stein (1996), where also the model of Bodner and Partom is studied, in Kunkel and Kollmann (1997), in Mahnken (1999Mahnken ( , 2002, and in Bruhns and Anding (1999).…”

Section: Introductionmentioning

confidence: 99%

Identification of material parameters for inelastic constitutive models: statistical analysis and design of experiments

Harth

Schwan

Lehn

et al. 2004

International Journal of Plasticity

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“…We present the algorithm PRINO which consists of the global cluster-oriented method of Price [35] in combination with the local optimization strategy of Müller, Nollau, and Polovinkin [33]. More research about parameter identification can be found e. g. in [4,9,26,28,30,31].…”

Section: Introductionmentioning

confidence: 99%

Identification of Material Parameters for Inelastic Constitutive Models Using Stochastic Methods

Harth

Lehn

2007

GAMM-Mitteilungen

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The parameters of a constitutive model are usually identified by minimization of the distance between model response and experimental data. However, measurement failures and differences in the specimens lead to deviations in the determined parameters. In this article we present our results of a study of these uncertainties for two constitutive models of Chaboche-type. The models differ only by a kinematic hardening variable. It turns out, that the kinematic hardening variable proposed by Haupt, Kamlah, and Tsakmakis yields a better description quality than the one of Armstrong and Frederick. For the parameter optimization as well as for the study of the deviations of the fitted parameters we apply stochastic methods. The available test data result from creep tests, tension-relaxation tests and cyclic tests performed on AINSI SS316 stainless steel at 600 O C. Since the amount of test data is too small for a proper statistical analysis we apply a stochastic simulation technique to generate artificial data which exhibit the same stochastic behaviour as the experimental data.

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Identification of constants of a viscoplastic constitutive model for a single crystal alloy

Cited by 11 publications

References 14 publications

Development of a Novel Hybrid Unified Viscoplastic Constitutive Model

Development of a Novel Hybrid Unified Viscoplastic Constitutive Model

Identification of material parameters for inelastic constitutive models: statistical analysis and design of experiments

Identification of Material Parameters for Inelastic Constitutive Models Using Stochastic Methods

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