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Improved Temperature Dependence of the Material Parameters in a Visco-plastic Chaboche Law for an Accurate Cyclic Hardening Modelling
Duchene, Laurent; Morch, Hélène; Habraken, Anne
2019The 8th edition of the International Conference on Computational Methods for Coupled Problems in Science and Engineering (COUPLED PROBLEMS 2019)
 

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Keywords :
Finite Element Analysis; Ni-alloy; Identification of Material parameters; High temperature
Abstract :
[en] In various industrial applications, the thermo-mechanical behaviour of the load bearing materials must be accurately modelled for a proper design of the key components. In this respect, a visco-plastic Chaboche type model [1] with advanced features such as kinematic and cyclic hardening, static and dynamic recovery, was implemented in a finite element code. Additionally, this constitutive model was coupled with a damage model in order to predict the lifetime of the material. Concerning the coupling in such thermo-mechanical model, beside the modelling of the elongation associated with temperature variations and the heat generated by plastic strains, it is very important to accurately reproduce the influence of the temperature on the mechanical behaviour. This can be conveniently achieved by varying the mechanical parameters as a function of the current temperature at the material point. In a first attempt to reproduce the temperature dependence of the material parameters, we calculated them by piecewise linear interpolations between values at pre-defined specific temperatures. A first drawback of this method is the large amount of parameters to be identified, as a complete determination of all the material parameters has to be performed at each specific temperature. A second and more important drawback is the discontinuity of the mechanical behaviour around the specific temperatures. Indeed, with piecewise interpolations, C0 continuity is fulfilled but not C1, which can be a significant issue during finite element simulations. [2] proposed to improve the temperature dependence of the material parameters by replacing the linear interpolations by a continuous analytical expression. In order to reproduce accurately the effects of the temperature, they used an exponential expression with 3 adjustable coefficients. Based on this idea, the present contribution proposes to use the sum of 2 exponential expressions. The influence of the temperature in the range of interest for each material parameter is therefore defined by 5 coefficients (instead of 3). The interest of such improvement is to be able to reproduce accurately the evolution of the cyclic hardening during high cycle loading, which was not possible with the method proposed by [2]. For instance, this is necessary when one wants to track the evolution of the stress amplitude as a function of the cycles in a strain imposed cyclic loading at various temperatures. REFERENCES [1] R. Ahmed, P.R. Barrett and T. Hassan, " Unified viscoplasticity modeling for isothermal low-cycle fatigue and fatigue-creep stress–strain responses of Haynes 230", Int. J. Solids Struct., Vol. 88-89, pp. 131-145, (2016). [2] E. Hosseini, S.R. Holdsworth, I. Kühn and E. Mazza, "Temperature dependent representation for Chaboche kinematic hardening model", Mater. High Temp., Vol. 32, pp. 404-411, (2015).
Disciplines :
Mechanical engineering
Author, co-author :
Duchene, Laurent  ;  Université de Liège - ULiège > Département ArGEnCo > Analyse multi-échelles des matériaux et struct. du gén. civ.
Morch, Hélène  ;  Université de Liège - ULiège > Département ArGEnCo > Analyse multi-échelles des matériaux et struct. du gén. civ.
Habraken, Anne  ;  Université de Liège - ULiège > Département ArGEnCo > Département ArGEnCo
Language :
English
Title :
Improved Temperature Dependence of the Material Parameters in a Visco-plastic Chaboche Law for an Accurate Cyclic Hardening Modelling
Publication date :
04 June 2019
Number of pages :
19
Event name :
The 8th edition of the International Conference on Computational Methods for Coupled Problems in Science and Engineering (COUPLED PROBLEMS 2019)
Event organizer :
Eugenio Oñate (Universitat Politècnica de Catalunya, Spain), Manolis Papadrakakis (National Technical University of Athens, Greece), Bernhard A. Schrefler (Università degli Studi di Padova, Italy)
Event place :
Sitges, Spain
Event date :
du 3 au 5 juin 2019
Audience :
International
Name of the research project :
Solar Perform
Funders :
Pôle MecaTech
Available on ORBi :
since 23 September 2019

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