Power Plant Component Design Using Creep-Damage Analysis

Kostenko, Yevgen; Lvov, Gennadiy; Gorash, Yevgen; Altenbach, Holm; Naumenko, Konstantin

doi:10.1115/imece2006-13710

Cited by 10 publications

(5 citation statements)

References 13 publications

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“…The underpinnings of DMNs need to be understood more thoroughly, and guidelines for its use, including preferred tools, need to be identified. The material parameters encompass a yield stress y 0 , a limiting stress y ∞ , a plastic hardening modulus h, an exponential hardening factor ω, a viscosity η, the creep constants C and k, creep prefactors A 1 as well as A 2 , a reference creep rate ε0 , and the creep exponent n. Details for the derivation of the material model [90,91], which may be cast in the framework of generalized standard material (GSM) [92], will be discussed elsewhere. The material model is discretized with an implicit Euler method in time.…”

Section: Discussionmentioning

confidence: 99%

Training deep material networks to reproduce creep loading of short fiber-reinforced thermoplastics with an inelastically-informed strategy

et al. 2022

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Deep material networks (DMNs) are a recent multiscale technology which enable running concurrent multiscale simulations on industrial scale with the help of powerful surrogate models for the micromechanical problem. Classically, the parameters of the DMNs are identified based on linear elastic precomputations. Once the parameters are identified, DMNs may process inelastic material models and were shown to reproduce micromechanical full-field simulations with the original microstructure to high accuracy. The work at hand was motivated by creep loading of thermoplastic components with fiber reinforcement. In this context, multiple scales appear, both in space (due to the reinforcements) and in time (short- and long-term effects). We demonstrate by computational examples that the classical training strategy based on linear elastic precomputations is not guaranteed to produce DMNs whose long-term creep response accurately matches high-fidelity computations. As a remedy, we propose an inelastically informed early stopping strategy for the offline training of the DMNs. Moreover, we introduce a novel strategy based on a surrogate material model, which shares the principal nonlinear effects with the true model but is significantly less expensive to evaluate. For the problem at hand, this strategy enables saving significant time during the parameter identification process. We demonstrate that the novel strategy provides DMNs which reliably generalize to creep loading.

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Section: Discussionmentioning

confidence: 99%

Training deep material networks to reproduce creep loading of short fiber-reinforced thermoplastics with an inelastically-informed strategy

et al. 2022

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“…The identification procedure is presented in [168], for example. (2.4.1), (2.4.2) and (2.4.5) experimental data of uni-axial creep up to rupture for certain stress and temperature ranges are required.…”

Section: Kachanov-rabotnov Modelmentioning

confidence: 99%

Modeling of Creep for Structural Analysis

Naumenko

Altenbach

2007

Foundations of Engineering Mechanics

152

109

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“…The procedure for identification of creep constants of a material at a variable temperature was detailed in [9][10][11]. Essentially, it consists in the least-squares approximation of experimental creep curves plotted for a wide range of temperatures and stresses.…”

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confidence: 99%

Creep and creep-rupture strength of gas turbine components in view of nonuniform temperature distribution

2008

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The conventional model of Kachanov-Rabotnov-Hayhurst continuum fracture mechanics is extended to cover the case of variable temperature and strain hardening. The creep and damage rates are assumed to depend on temperature. The resulting model for nonisothermal creep and damageability is implemented in a finite-element code of the general-purpose software package ABAQUS. The mathematical model is tested on an axisymmetric problem for a gas turbine body.Keywords: creep and damage rates, model for nonisothermal creep and damageability.Structural parts of gas turbines have to operate under elevated temperatures and complex stresses over a long a period of time. A study of creep in the structures including the damage accumulation is required for a reliable assessment of their creep rupture strength. Many elements of power-generating plants -high-and low-pressure turbine stages, exhaust manifolds, diffusers -run in a nonunifom temperature field; therefore, a problem on nonisothermal creep and damageability should be stated. This is especially important for thick-walled elements of turbine bodies, where internal pressure is combined with large temperature gradients.Metallographic studies of heat-resistant steels suggest a significant complexity and diversity of physical processes that occur at various creep stages. It may be inferred that the diffusion-controlled migration of dislocations prevails at the second stage of creep. Various mechanisms of the interaction between particles and dislocations as well as the time-dependent alterations in the material microstructure can take place during the thirst stage of creep, leading to the strength degradation and thus to fracture. The activation energies for the diffusion and dislocation processes differently depend on temperature; this fact was taken into account during the development of a creep model including damageability at variable temperature.Thus, the nonisothermal creep model allowing for damageability, which is put forward here, is based on Kachanov-Rabotnov-Hayhurst model [1-3] and physical mechanisms of creep for typical heat-resistant steels. For adequate description of the primary creep stage we introduce a strain hardening function in the formTo specify the different temperature effects on the diffusion creep and cross sliding of dislocations, we use two different functional relations: the first one is entered into the constitutive equation for creep strain rate and the second one into the evolution equation that determines the damage rate. The temperature dependence of these relations is described by the Arrhenius function [4]:For uniaxial stress, the equations for creep and damageability including strain hardening for variable temperature fields are written as 0039-2316/08/4005-0525

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Power Plant Component Design Using Creep-Damage Analysis

Cited by 10 publications

References 13 publications

Training deep material networks to reproduce creep loading of short fiber-reinforced thermoplastics with an inelastically-informed strategy

Training deep material networks to reproduce creep loading of short fiber-reinforced thermoplastics with an inelastically-informed strategy

Modeling of Creep for Structural Analysis

Creep and creep-rupture strength of gas turbine components in view of nonuniform temperature distribution

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