scholarly journals Defects in Electron Beam Melted Ti-6Al-4V: Fatigue Life Prediction Using Experimental Data and Extreme Value Statistics

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 640
Author(s):  
Viktor Sandell ◽  
Thomas Hansson ◽  
Sushovan Roychowdhury ◽  
Tomas Månsson ◽  
Mats Delin ◽  
...  
Keyword(s):  
Electron Beam ◽  
Fatigue Life ◽  
Defect Formation ◽  
Production Method ◽  
Extreme Value ◽  
Extreme Value Statistics ◽  
Material Defects ◽  
Model Input ◽  
X Ray Computed ◽  
Critical Components

Electron beam melting is a powder bed fusion (PBF) additive manufacturing (AM) method for metals offering opportunities for the reduction of material waste and freedom of design, but unfortunately also suffering from material defects from production. The stochastic nature of defect formation leads to a scatter in the fatigue performance of the material, preventing wider use of this production method for fatigue critical components. In this work, fatigue test data from electron beam melted Ti-6Al-4V specimens machined from as-built material are compared to deterministic fatigue crack growth calculations and probabilistically modeled fatigue life. X-ray computed tomography (XCT) data evaluated using extreme value statistics are used as the model input. Results show that the probabilistic model is able to provide a good conservative life estimate, as well as accurate predictive scatter bands. It is also shown that the use of XCT-data as the model input is feasible, requiring little investigated material volume for model calibration.

On the spectral shape of SEP events: An extreme value statistics approach

2013 ◽  
Author(s):  
M. Laurenza ◽  
G. Consolini ◽  
M. Storini ◽  
A. Damiani
Keyword(s):  
Extreme Value ◽  
Spectral Shape ◽  
Extreme Value Statistics

scholarly journals Influence of Material Ductility on Fatigue Life under Multiaxial Proportional and Non-Proportional Normal and Shear Stresses

2019 ◽  
Vol 300 ◽  
pp. 17001 ◽  
Author(s):  
Cetin Morris Sonsino
Keyword(s):  
Fatigue Life ◽  
Tensile Elongation ◽  
Shear Stresses ◽  
Normal Strain ◽  
Proportional Loading ◽  
Ductile Materials ◽  
Critical Components ◽  
Material Ductility ◽  
Fatigue Life Reduction ◽  
Normal And Shear Stresses

Current experiences show that a non-proportional loading of ductile materials such as wrought steels, wrought aluminium or magnesium alloys, not welded or welded, causes a significant fatigue life reduction under an out-of-phase shear strain or shear stress superimposed on a normal strain or normal stress compared with proportional in-phase loading. However, when ductility, here characterised by tensile elongation, is reduced by a heat treatment or by another manufacturing technology such as casting or sintering, the afore-mentioned life reduction is compensated or even inversed, i. e. longer fatigue life results compared with proportional loading. Some actual results, determined with additive manufactured titanium, suggest that microstructural features such as manufacturing-dependent internal defects like microporosities should be considered in addition to the ductility level. This complex life behaviour under non-proportional loading cannot always be estimated. Therefore, in experimental proofs of multiaxial loaded parts, especially safety-critical components or structures, with real or service-like signals, emphasis must be placed on retaining non-proportionalities between loads and stresses/strains, respectively.

scholarly journals Bestimmung seltener Starkniederschläge kurzer Dauer - Fallbeispiele im Vergleich mit den schweizerischen Starkniederschlagskarten | Determination of Rare Rainfall Intensities of Short-Duration - Case Studies Compared with Maps of Intense Rainfall in Switzerland

1999 ◽  
Vol 150 (6) ◽  
pp. 209-218 ◽  
Author(s):  
Felix Forster ◽  
Walter Baumgartner
Keyword(s):  
Case Studies ◽  
Short Duration ◽  
Extreme Value ◽  
Extreme Value Statistics ◽  
Intense Rainfall

The two maps of intense rainfall in the Hydrological Atlas of Switzerland (1992, 1997) are compared to data of an evaluation of extreme value statistics. The results are transferred to recommendations for practioners.

scholarly journals Evaluation of Fatigue Characteristics of Aluminum Alloys and Mechanical Components Using Extreme Value Statistics and C-specimens

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1915
Author(s):  
Jungsub Lee ◽  
Sang-Youn Park ◽  
Byoung-Ho Choi
Keyword(s):  
Aluminum Alloys ◽  
Fem Analysis ◽  
Extreme Value ◽  
Fatigue Tests ◽  
Extreme Value Statistics ◽  
Fatigue Properties ◽  
Chemical Compositions ◽  
Cross Sectional ◽  
Fatigue Characteristics ◽  
Mechanical Components

In this study, the fatigue characteristics of aluminum alloys and mechanical components were investigated. To evaluate the effect of forging, fatigue specimens with the same chemical compositions were prepared from billets and forged mechanical components. To evaluate the cleanliness of the aluminum alloys, the cross-sectional area of specimens was observed, and the maximum inclusion sizes were obtained using extreme value statistics. Rotary bending fatigue tests were performed, and the fracture surfaces of the specimens were analyzed. The results show that the forging process not only elevated the fatigue strength but also reduced the scatter of the fatigue life of aluminum alloys. The fatigue characteristics of C-specimens were obtained to develop finite-element method (FEM) models. With the intrinsic fatigue properties and strain–life approach, the FEM analysis results agreed well with the test results.

scholarly journals Создание локализованных ансамблей NV-центров в CVD-алмазе с помощью облучения электронным пучком

2019 ◽  
Vol 45 (6) ◽  
pp. 36
Author(s):  
С.А. Богданов ◽  
А.М. Горбачев ◽  
Д.Б. Радищев ◽  
А.Л. Вихарев ◽  
М.А. Лобаев ◽  
...  
Keyword(s):  
Electron Beam ◽  
Defect Formation ◽  
Cvd Diamond ◽  
Diamond Lattice ◽  
Subsequent Annealing ◽  
Optical Measurements ◽  
Nitrogen Doped ◽  
Nv Center ◽  
Delta Layer

AbstractCreation of localized NV center ensembles, produced by irradiation of CVD diamond with nitrogen doped delta-layer with 200 keV electron beam and the subsequent annealing is demonstrated. Results of optical measurements of activated areas at different irradiation doses are presented. Issues concerning defect formation in diamond lattice during the electron beam impact are discussed.

scholarly journals In-situ estimation of defect volume from parameters of acoustic emission signals

2021 ◽  
Vol 2103 (1) ◽  
pp. 012066
Author(s):  
E E Damaskinskaya ◽  
V L Hilarov ◽  
I A Panteleev ◽  
D V Korost ◽  
K A Damaskinskii
Keyword(s):  
Acoustic Emission ◽  
Defect Formation ◽  
Heterogeneous Material ◽  
Joint Analysis ◽  
Defect Accumulation ◽  
Computed Microtomography ◽  
X Ray Computed ◽  
Average Defect ◽  
Ct Data ◽  
Defect Volume

Abstract By using two methods of nondestructive testing, i.e., acoustic emission (AE) measurements and X-ray computed microtomography (CT), an experimental study of defect accumulation during a uniaxial compression of a natural heterogeneous material was carried out. A joint analysis of the AE and CT data revealed a correspondence between energy characteristics of the acoustic emission accompanying defect formation and volume of defects. It is shown that the dependence of the total energy of AE signals on the defect volume is linear, which is consistent with the phenomenological dependences for earthquake focuses obtained earlier. The linear dependence was used to estimate the average defect size. It is shown that, regardless of the assumed defect shape, its average linear size does not exceed 100 μm.

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