The effects of notch size and material microstructure on the notch sensitivity factor for notched components

Owolabi, Gbadebo; Okeyoyin, Oluwamayowa; Bamiduro, Oluwakayode; Olasumboye, Adewale; Whitworth, Horace

doi:10.1016/j.engfracmech.2015.03.026

Cited by 13 publications

(5 citation statements)

References 41 publications

(52 reference statements)

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“…While Karry and Dolan provide a formula for the dependency of the fatigue notch factor k f on grain size in brass specimens [32], a robust relation between grain size and the notch support parameters A and k for the geometry independent notch support factor n χ is yet to be found. Note that A and k are single values and not explicitly considered to be statistically distributed as k f in [17] for example. Instead, all additional data scatter emanating from the notch support effect is covered by the Weibull shape parameter m during the model calibration.…”

Section: Comparison Of Notch Support Mechanism In Different Materialsmentioning

confidence: 99%

“…Another probabilistic approach to notch support is presented in [16] and [17], for example where fatigue notch factors for high cycle fatigue (HCF) based on the random distribution of failure inducing defects in the material are computed. Hertel et al already take into account a macro support factor which combines the statistical size effect and geometrical support effects [18].…”

Section: Introductionmentioning

confidence: 99%

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

Mäde

Schmitz

Gottschalk

et al. 2018

Computational Materials Science

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In recent years a local probabilistic model for low cycle fatigue (LCF) based on the statistical size effect has been developed and applied on engineering components. Here, the notch support extension based on the stress gradient effect is described in detail, as well as an FEA-based parameter calibration. An FEA is necessary to simulate non-homogeneous stress fields in non-smooth specimens which exhibit gradients and determine size effects. The hazard density approach and the surface integration over the FEA stress lead to geometryindependent model parameters. Three different materials (superalloys IN-939, Rene80, steel 26NiCrMoV14-5 ) and three different geometry types (smooth, notch, cooling hole specimens) are considered for a more comprehensive validation of the probabilistic LCF model and to demonstrate its wide application range. At the same time, a reduced testing effort is needed compared to deterministic model predictions with notch support.

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Section: Comparison Of Notch Support Mechanism In Different Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Mäde

Schmitz

Gottschalk

et al. 2018

Computational Materials Science

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show abstract

“…The equations that model these finite elements are assembled into a system of equations that models the entire problem. The FEA application covers a wide range of engineering and scientific problems [18][19][20][21]. Owolabi et al studied the notch root radius effect on the probability of failure [18].…”

Section: Introductionmentioning

confidence: 99%

“…The FEA application covers a wide range of engineering and scientific problems [18][19][20][21]. Owolabi et al studied the notch root radius effect on the probability of failure [18]. Chaves et al correlated the stress gradient at the notch obtained through FEA to the fatigue behavior [19].…”

Section: Introductionmentioning

confidence: 99%

Fatigue Analysis of Threaded Components with Cd and Zn-Ni Anticorrosive Coatings

Santos

Fernandes

Velloso

et al. 2021

Metals

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The influence of the electrodeposition of cadmium and zinc-nickel and the stress concentration effect on the fatigue behavior of AISI 4140 steel threaded components were studied. Axial fatigue tests at room temperature with a stress ratio of R = 0.1 were performed using standard and threaded specimens with and without nut interface under base material, cadmium, and zinc-nickel-coated conditions. Finite element analysis (FEA) was used, considering both elastic and elastoplastic models, to quantify the stress distribution and strain for threaded specimens with and without a nut interface. The numeric results were correlated to the experimental fatigue data of threaded components with and without the nut interface, to allow the oil & gas companies to extrapolate the results for different thread dimensions, since the experimental tests are not feasible to be performed for all thread interfaces. Scanning electron microscopy (SEM) was used to analyze the fracture surfaces. The stress concentration factor had a greater influence on the fatigue performance of threaded components than the effect of the Cd and Zn-Ni coatings. The fatigue life of studs reduced by about 58% with the nut/stud interface, compared to threaded components without nuts. The elastoplastic FEA results showed that studs with a stud/nut interface had higher stress values than the threaded specimens without a nut interface. The FEA results showed that the cracks nucleated at the regions with higher strain, absorbed energy, and stress concentration. The substitution of Cd for a Zn-Ni coating was feasible regarding the fatigue strength for threaded and smooth components.

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“…Many authors studied the influence of notch size and geometry on different alloys strength. Owolabi et al [15] studied the influence of notch size and material microstructure on notch sensitivity for an IN 100 superalloy. They simulated a probabilistic 2 of 24 mesomechanics model and compared it with experimental results and concluded that the probability of failure, fatigue notch factor and associated notch sensitivity index increases with the increasing notch root radius.…”

Section: Introductionmentioning

confidence: 99%

Tensile Notch Sensitivity of Additively Manufactured IN 625 Superalloy

2020

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The notch sensitivity of additively manufactured IN 625 superalloy produces by laser powder bed fusion (LPBF) has been investigated by tensile testing of cylindrical test pieces. Smooth and V-notched test pieces with four different radii were tested both in as-built state and after a stress relief heat treatment for 1 h at 900 °C. Regardless of the notch root radius, the investigated alloy exhibits notch strength ratios higher than unity in both as-built and in stress-relieved states, showing that the additive manufactured IN 625 alloy is not prone to brittleness induced by the presence of V-notches. Higher values of notch strength ratios were recorded for the as-built material as a result of the higher internal stress level induced by the manufacturing process. Due to the higher triaxiality of stresses induced by notches, for both as-built and stress-relieved states, the proof strength of the notched test pieces is even higher than the tensile strength of the smooth test pieces tested in the same conditions. SEM fractographic analysis revealed a mixed mode of ductile and brittle fracture morphology of the V-notched specimens regardless the notch root radius. A more dominant ductile mode of fracture was encountered for stress-relieved test pieces than in the case of the as-built state. However, future research is needed to better understand the influence of notches on additive manufactured IN 625 alloy behaviour under more complex stresses.

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The effects of notch size and material microstructure on the notch sensitivity factor for notched components

Cited by 13 publications

References 41 publications

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

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

Fatigue Analysis of Threaded Components with Cd and Zn-Ni Anticorrosive Coatings

Tensile Notch Sensitivity of Additively Manufactured IN 625 Superalloy

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