High-Temperature Life Assessment of Exhaust Components and the Procedure for Accelerated Durability and Reliability Testing

Wei, Zhigang; Yang, Fulun; Lin, Shengbin; Luo, Limin; Konson, Dmitri

doi:10.4271/2012-01-2058

Cited by 4 publications

(11 citation statements)

References 22 publications

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“…The life of 441 steel is slightly shorter than that of 409 steel in terms of mean cycle number to failure. It should be noted that the thickness are different and generally the thicker the specimen the shorter the life (e.g. for 309 steel, the thermal fatigue lives are 2.281 versus 4.521, a factor about 2.0, in terms of mean lives as thickness goes down from H = 2.0 to H = 1.5 for all other conditions being the same) and the thermal fatigue life is very sensitive to thickness, which can be supported by thermal stress theory and by experimental observations.…”

Section: Factors That Effect Thermal Fatigue Lifementioning

confidence: 55%

“…The V‐shape specimen testing approach is such a very useful tool for evaluating thermal fatigue resistance of exhaust components. The V‐shape testing is a relatively mature testing method, and in conjunction with computational fluid dynamics and finite element analysis, it has been used for exhaust manifold material damage and thermal fatigue resistance characterization …”

Section: V‐shape Specimen Testing For Thermal Fatigue Resistance Assementioning

confidence: 99%

“…It is found that, for a given grade, the thermal fatigue life depends on the maximum and minimum temperature of the cycle, hold (dwell) time at the maximum temperature, specimen thickness, fixture distance, loading profile and welding type. Careful examination of the test configuration and the Buckingham theorem indicates that the cycles to failure N f can be expressed in the following form:

N_{f} = C {((), ΔT)}^{χ} {((), H)}^{ω_{1}} {((), W)}^{ω_{2}} g (italicΔt)

where C , χ , ω 1 and ω 2 are constants; ΔT is the temperature range and Δt is the hold time; and H and W are the thickness and the fixture distance, respectively. The formulae for g ( Δt ) will be given shortly.…”

Section: Factors That Effect Thermal Fatigue Lifementioning

confidence: 99%

“…For example, new generation of nuclear power production requires increased temperature and mechanical loading; current peak gas temperatures of 1000 °C can be reached in advanced exhaust manifolds, which are usually the hottest part of conventional exhaust systems. The peak temperature in a recently developed active regeneration system for diesel particulate filters can reach even higher . The deformation and failure mechanisms are very complex under the combined effects of cyclic thermal–mechanical loadings.…”

Section: Introductionmentioning

confidence: 99%

“…The deformation and failure mechanisms are very complex under the combined effects of cyclic thermal–mechanical loadings. Fatigue, creep, oxidation, corrosion or their combinations are the major failure mechanisms . Life assessment and thermal fatigue resistance evaluation of these exhaust components and systems is vital to produce structurally optimized and robust designs.…”

Section: Introductionmentioning

confidence: 99%

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Thermal fatigue resistance characterization and ranking of materials using the V‐shape specimen testing method

Wei

Konson

Yang

et al. 2014

Fatigue Fract Eng Mat Struct

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A B S T R A C T Thermal fatigue resistance of materials is an extremely important criterion for the longterm durability and reliability performance of very high-temperature components and systems, such as advanced auto engine and exhaust systems. There is a broad range of material choices for thermal fatigue resistance applications. The final selection of the materials depends on the balance of engineering performance of the materials and the cost. To optimize the thermal fatigue resistance and cost of those materials, a reliable testing procedure for material thermal fatigue characterization and a material evaluation/selection matrix must be established. In this paper, the V-shape specimen testing method in evaluating thermal fatigue resistance performance is introduced first. The influence of several factors, such as the thickness of specimens, operating temperature and hold time, on the thermal fatigue resistance is experimentally investigated. Subsequently, the statistical and probabilistic characteristics of the thermal fatigue failure data are analysed to reveal the possible failure mechanisms. Finally, a general rational approach for thermal fatigue resistance characterization and ranking is demonstrated, and a simple parameter λ = kσ f /Eα, which combines the material strength, thermal conductivity and thermal expansion, is found to be the new breakthrough parameter, correlating to V-shape thermal fatigue test results. Results on four currently used stainless steels verify the correlations and indicate the validity of this approach. , C 3 = coefficients in fatigue life models c = specific heat E = elastic modulus F(x) = cumulative distribution function (CDF) f(x) = probability density function (PDF) g() = function related to hold time H = thickness of the V-shape specimen k = thermal conductivity N f = cycles to failure n = sample size or test number s = sample standard deviation T = temperature T m = melting temperature ΔT = temperature range Δt = hold time W = fixture distance x = a variable λ = thermal fatigue (thermal shock) resistance parameter α = thermal expansion coefficient ρ = density Correspondence: Z. Wei.

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Section: Factors That Effect Thermal Fatigue Lifementioning

confidence: 55%

Section: V‐shape Specimen Testing For Thermal Fatigue Resistance Assementioning

confidence: 99%