High temperature LCF life prediction of notched DS Ni-based superalloy using critical distance concept

Yang, Xiaoguang; Wang, Jingke; Liu, Jinlong

doi:10.1016/j.ijfatigue.2011.05.018

Cited by 64 publications

(25 citation statements)

References 15 publications

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“…As a result, two prediction methods were proposed aiming at different features: one was termed the notch prediction based on the continuum mechanics, and another one was termed the crack prediction based on the fracture mechanics. 41 Furthermore, it was pointed out by Taylor and co-workers that the critical distance became a variable quantity when the size of specimens was small compared with the size of the critical distance. cracks as well as notches) by unifying the LEFM and the process zone approaches.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of notch size effect on LCF life of TA19 specimens based on the stress gradient modified critical distance method

Wang

Liu

et al. 2018

Fatigue Fract Eng Mat Struct

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In the present study, the stress gradient modified critical distance method is proposed to predict the low‐cycle fatigue lifetime of notched TA19 specimens by introducing a weight function of relative stress gradient into conventional critical distance theories. The accuracy and reliability of the proposed method were validated based on the experimental data by performing low‐cycle fatigue tests on smooth bar TA19 specimens as well as geometrically similar plate specimens containing a bore hole (BHP). Predicted results demonstrate that the mean absolute errors for entire tested specimens using the stress gradient modified critical distance method on the basis of the point method and the line method are 7.49% and 7.41% respectively. Furthermore, the fatigue striation width at the fracture surface was determined by scanning electronic microscope observations to examine the stress gradient effect on the crack growth rate.

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Section: Discussionmentioning

confidence: 99%

Evaluation of notch size effect on LCF life of TA19 specimens based on the stress gradient modified critical distance method

Wang

Liu

et al. 2018

Fatigue Fract Eng Mat Struct

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“…Differing from Lanning's ideas of substituting the damage relevant parameter, in LCF analysis of notched directionally solidified (DS) Ni‐based superalloy, Yang et al and Wang and Yang[92] corrected Equation by incorporating the linear elastic stress concentration factor K t :

K_{t} \times L = A N_{f}^{B} .

…”

Section: Critical Distance Theory and Its Applications To Fatiguementioning

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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“…In this method, fatigue cracking is treated as initiating at a critical distance below the notch-root where the stress has attenuated from its peak at the root of the notch [17,18]. The critical distance is found by regressing fatigue test data from smooth bars and notched bars of various known stress concentration factors.…”

Section: Fatigue Cracking At the Cooling Holesmentioning

confidence: 99%

Stress Rupture and Fatigue in Thin Wall Single Crystal Superalloys with Cooling Holes

Sun¹,

Heffernan²,

Helmink³

2012

Superalloys 2012 (Twelfth International Symposium)

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High pressure turbine airfoils made of single crystal superalloys are often in the form of thin walls containing numerous small holes. These features, essential for the effective cooling of turbine airfoils, present special stress rupture and fatigue failure mechanisms that are not present in bulk single crystals. The objective of this paper is to further the understanding of stress rupture and fatigue of thin wall structures and to find how mechanical property models ordinarily appropriate for bulk superalloys may be modified for use on thin wall structures. Stress rupture properties of thin wall CMSX-4 single crystals, bare and with three types of coatings, were tested and compared with the stress rupture behavior of bulk materials. A model that captures the degradation mechanisms in thin wall structures and allows a quantitative prediction of the stress rupture time of thin-wall turbine airfoils is introduced. The paper also addresses low cycle fatigue crack initiation at cooling holes by testing thin-wall CMSX-4 single crystals at cyclic load conditions that mimic those found in actual turbine airfoils. Finite element calculations show that, even though the cooling holes are under an overall in-plane compressive stress, local stresses driving fatigue crack development are tensile due to local plastic deformation. With the mechanism-based approach, this work shows that it is possible to modify mechanical behavior models developed for bulk single crystal superalloys so that they can be used for component life calculations of thin wall structures.

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High temperature LCF life prediction of notched DS Ni-based superalloy using critical distance concept

Cited by 64 publications

References 15 publications

Evaluation of notch size effect on LCF life of TA19 specimens based on the stress gradient modified critical distance method

Evaluation of notch size effect on LCF life of TA19 specimens based on the stress gradient modified critical distance method

Recent advances on notch effects in metal fatigue: A review

Stress Rupture and Fatigue in Thin Wall Single Crystal Superalloys with Cooling Holes

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