A multi-mechanism damage coupling model

Xiao, Yingchun

doi:10.1016/j.ijfatigue.2004.02.004

Cited by 26 publications

(22 citation statements)

References 6 publications

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“…The proposed CDM model relates the effects of anode microstructure defects to parametric quantities that can be observed and measured at the macroscopic scale, such as material stiffness. The CDM model accounts for material degradation in a phenomenological way through a degradation variable ( D ) that governs the reduction of the homogenized elastic modulus 12,13 : where E 0 is the initial elastic modulus and E is the elastic modulus of degraded material, as shown in Fig. 1.…”

Section: Anode Degradation Modelmentioning

confidence: 99%

“…Several mechanisms are involved in the process of anode material degradation. Each mechanism requires a different degradation variable to be specified 13 . In the proposed degradation model, we have specified two degradation variables: (1) a thermomechanical degradation variable ( D m ), which is associated with stresses and the thermal aging effect and (2) a chemical degradation variable ( D c ), which is associated with the effects of coal syngas contaminants on the anode microstructure and mechanical strength.…”

Section: Anode Degradation Modelmentioning

confidence: 99%

“…For brittle material, the free energy associated with the plastic hardening ψ p (α) is negligible. Similar to Xiao 13 and Dorgan, 23 we propose the Helmholtz‐free energy in the form of the following equation: where C ijkl is the initial stiffness, ρ is the density, and h, n , and κ are material parameters to be determined experimentally. We chose n =1 as a simple case 21 .…”

Section: Anode Degradation Modelmentioning

confidence: 99%

See 2 more Smart Citations

Durability Prediction of Solid Oxide Fuel Cell Anode Material under Thermomechanical and Fuel Gas Contaminant Effects

Iqbal¹,

Guo²,

Kang³

et al. 2009

International Journal of Applied Ceramic Technology

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Solid oxide fuel cells (SOFCs) operate under harsh environments, which cause the deterioration of anode material properties and service life. In addition to electrochemical performance, the structural integrity of the SOFC anode is essential for successful long‐term operation. The SOFC anode is subjected to stresses at high temperature, thermal/redox cycles, and fuel gas contaminant effects during long‐term operation. These mechanisms can alter the anode microstructure and affect its electrochemical and structural properties. In this research, anode material degradation mechanisms are briefly reviewed and an anode material durability model is developed and implemented in finite‐element analysis. The model takes into account thermomechanical and fuel gas contaminant degradation mechanisms for predicting the long‐term structural integrity of the SOFC anode. The proposed model is validated experimentally using a NexTech Probostat™ SOFC button cell test apparatus integrated with a Sagnac optical setup for simultaneously measuring electrochemical performance and in situ anode surface deformation.

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Section: Anode Degradation Modelmentioning

confidence: 99%

Section: Anode Degradation Modelmentioning

confidence: 99%

Section: Anode Degradation Modelmentioning

confidence: 99%

See 1 more Smart Citation

Durability Prediction of Solid Oxide Fuel Cell Anode Material under Thermomechanical and Fuel Gas Contaminant Effects

Iqbal¹,

Guo²,

Kang³

et al. 2009

International Journal of Applied Ceramic Technology

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“…34 Thus, the model capabilities can be extended to thermomechanical fatigue and high-cycle fatigue. 35,36 Some investigations were also performed in order to understand crack initiation phenomena. Indeed, Cailletaud and Levaillant 37 have divided the fatigue damage component into two stages as a crack microinitiation and a crack micropropagation.…”

Section: Stress-formulated Approachmentioning

confidence: 99%

“…Influences of temperature evolution within cycles and material ageing on the lifetime can also be considered 34 . Thus, the model capabilities can be extended to thermomechanical fatigue and high‐cycle fatigue 35,36 . Some investigations were also performed in order to understand crack initiation phenomena.…”

Section: Introductionmentioning

confidence: 99%

A continuum damage model applied to high‐temperature fatigue lifetime prediction of a martensitic tool steel

Velay¹,

Bernhart²,

Delagnes³

et al. 2005

Fatigue Fract Eng Mat Struct

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A B S T R A C T High-temperature operational conditions of hot work tool steels induce several thermomechanical loads. Depending on the processes, (i.e. forging, die casting or extrusion), stress, strain, strain rate and temperature levels applied on the material are nevertheless very different. Thus, lifetime prediction models need to be able to take into account a broad range of working conditions. In this paper, a non-isothermal continuum damage model is identified for a widely used hot work tool steel AISI H11 (X38CrMoV5) with a nominal hardness of 47 HRc. This investigation is based on an extensive high-temperature, lowcycle fatigue database performed under strain rate controlled conditions with and without dwell times in the temperature range 300-600 • C . As analysis of experimental results does not reveal significant time-dependent damage mechanisms, only a fatigue damage component was activated in the model formulation. After normalization, all fatigue results are defined on a master Woehler curve defined by a nonlinear damage model, which allows the parameter identification. Last, a validation stage of the model is performed from thermomechanical fatigue tests.Keywords continuum damage mechanics; fatigue life prediction; high-temperature fatigue; tempered martensitic steels; Woehler curve. N O M E N C L A T U R E D = fatigue damage value a, β, M, α, b = fatigue model parameters < u > = u.H(u), the McCauley brackets with H the Heaviside function N R = number of cycles to failure σ M = mid-life maximal stress σ m = mid-life minimal stress ε p = mid-life strain range σ = mid-life mean stress σ = mid-life stress range S m = reduced mid-life minimal stress S M = reduced mid-life maximal stress S = reduced mid-life stress range σ u = ultimate stress σ l = fatigue limit σ l 0 = fatigue limit for zero mean stress I N T R O D U C T I O NHot work tool steels undergo very critical thermomechanical loads that are usually very hard to evaluate from an Correspondence: V. Velay. experimental point of view and whose levels strongly depend on the location on the structure. Numerical simulation seems to be adequate to reach this information in order to optimize the tool design and to improve their lifetime. For that purpose, several preliminary stages are necessary. First of all, a cyclic elasto-viscoplastic behaviour model has to be identified in order to provide stress-strain

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Numerical simulation of cyclic behavior of ductile metals with a coupled damage–viscoplasticity model

Khoei

Eghbalian

2012

Computational Materials Science

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A multi-mechanism damage coupling model

Cited by 26 publications

References 6 publications

Durability Prediction of Solid Oxide Fuel Cell Anode Material under Thermomechanical and Fuel Gas Contaminant Effects

Durability Prediction of Solid Oxide Fuel Cell Anode Material under Thermomechanical and Fuel Gas Contaminant Effects

A continuum damage model applied to high‐temperature fatigue lifetime prediction of a martensitic tool steel

Numerical simulation of cyclic behavior of ductile metals with a coupled damage–viscoplasticity model

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