Combined notch and size effect modeling in a local probabilistic approach for LCF

Mäde, Lucas; Schmitz, Sebastian; Gottschalk, Hanno; Beck, Tilmann

doi:10.1016/j.commatsci.2017.10.022

Cited by 65 publications

(49 citation statements)

References 17 publications

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“…Prob. Wöhler curves and cooling hole specimen LCF test data of IN‐939 at 649 ° C . The “low” and “high” axis ticks correspond to the same cycle numbers as in all other Wöhler plots in this work…”

Section: Theorymentioning

confidence: 90%

“…Mäde et al have shown how the combined local probabilistic model differentiates between size effect shift ΔN SizEff in N ‐direction and the stress gradient shift in E ‐direction, which is equivalent to another LCF life shift ΔN StGradEff (see Figure ).…”

Section: Theorymentioning

confidence: 99%

“…A combined size and stress gradient effect prediction can be achieved by applying a local stress gradient ( χ ) support parameter n χ when calculating the local deterministic life

\frac{ε_{a} ((), x)}{n_{χ} ((), χ ((), x))} = \frac{σ_{f}^{'} - σ_{m} ((), x)}{E} \cdot {(2 N_{i_{\det}} (bold-italicx))}^{b} + ε_{f}^{'} \cdot {(2 N_{i_{\det}} (bold-italicx))}^{c}

…”

Section: Theorymentioning

confidence: 99%

“…The respective life scale values η j ( ε aj , T j ) are predicted using simultaneously calibrated CMB coefficients. These are calculated with temperature surrogate models as in our previous work . The Weibull shape parameter m is assumed to be constant over temperature.…”

Section: Lcf Tests and Predictions Of Component Similar Specimensmentioning

confidence: 99%

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Evaluation of component‐similar rotor steel specimens with a local probabilistic approach for LCF

Mäde

Kumar²,

Schmitz

et al. 2019

Fatigue Fract Eng Mat Struct

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Lately, a successful validation of a combined size and gradient effect modelling approach in a local probabilistic framework for LCF was published. A second validation study is here presented using LCF data of component‐similar specimens made of forged X12CrMoWVNbN10‐1‐1. It is found that a reasonable LCF crack initiation life prediction can be achieved by the local probabilistic model using single batch material parameters. However, the material parameters obtained from mixed batch LCF test data overestimate the actual material inherent LCF life scatter. Consequently, the size effect shift is pronounced too much, and the LCF life is predicted beyond crack initiation. Estimating the material parameters from a single batch data set instead results in a much less dispersed LCF life distribution and an approximately correct size effect shift. The predicted median Wöhler curve then corresponds to borehole‐specimen lives for initial cracks at the detection threshold. A reasonable prediction of technically relevant crack sizes in such inhomogeneous components requires additional modelling of stress gradient effects.

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Section: Theorymentioning

confidence: 90%

Section: Theorymentioning

confidence: 99%

“…A combined size and stress gradient effect prediction can be achieved by applying a local stress gradient ( χ ) support parameter n χ when calculating the local deterministic life

\frac{ε_{a} ((), x)}{n_{χ} ((), χ ((), x))} = \frac{σ_{f}^{'} - σ_{m} ((), x)}{E} \cdot {(2 N_{i_{\det}} (bold-italicx))}^{b} + ε_{f}^{'} \cdot {(2 N_{i_{\det}} (bold-italicx))}^{c}

…”

Section: Theorymentioning

confidence: 99%

Section: Lcf Tests and Predictions Of Component Similar Specimensmentioning

confidence: 99%

See 2 more Smart Citations

Evaluation of component‐similar rotor steel specimens with a local probabilistic approach for LCF

Mäde

Kumar²,

Schmitz

et al. 2019

Fatigue Fract Eng Mat Struct

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“…Recently, Mäde et al coupled the Coffin‐Manson‐Basquin (CMB) equation and Seibel's empirical formula into probabilistic low cycle fatigue (LCF) risk evaluation of turbine vanes. Specifically, the notch support factor n χ is utilized directly in the form of

1 + A_{χ} \times χ^{k_{χ}}

, where A χ and k χ are material‐dependent notch support parameters.…”

Section: Introductionmentioning

confidence: 99%

Recent advances on notch effects in metal fatigue: A review

Liao

Zhu

Correia

et al. 2020

Fatigue Fract Eng Mat Struct

173

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Notch features including holes, fillets, shoulders, and grooves commonly exist in engineering components. When subjected to external loads, these geometrical discontinuities generally act as stress raisers and thus present significant influences on the component strength and life, which are more remarkable under complex loading paths. Accordingly, numerous theories and approaches have been developed to address notch effects in metal fatigue as well as damage modelling and life predictions, which aim to provide theoretical support for structural optimal design and integrity evaluation. However, most of them are self‐styled or focus on specific objects, which limits their engineering applicability. This review recalls recent developments and achievements in notch fatigue modelling and analysis of metals. In particular, four commonly used methods for fatigue evaluation of metallic notched components/structures are summarized and elaborated, namely, nominal stress approaches, local stress‐strain approaches, and critical distance theories and weighting control parameters‐based approaches, which intend to provide a reference for further research on notch fatigue analysis and promote the integration and/or development among different approaches for practice.

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