scholarly journals Multiaxial fatigue life assessment in notched components based on the effective strain energy density

2020 ◽  
Vol 28 ◽  
pp. 1808-1815
Author(s):  
R. Branco ◽  
J.D. Costa ◽  
L.P. Borrego ◽  
F. Berto ◽  
J. Razavi ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Energy Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Effective Strain ◽  
Multiaxial Fatigue ◽  
Life Assessment ◽  
Fatigue Life Assessment ◽  
Notched Components

A Modified Closed Form Energy Based Framework for Fatigue Life Assessment for Aluminum 6061-T6—Damaging Energy Approach

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
M.-H. Herman Shen ◽  
Sajedur R. Akanda
Keyword(s):  
Fatigue Life ◽  
Energy Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Strain Range ◽  
Life Assessment ◽  
Cycle Fatigue ◽  
Average Strain ◽  
Plastic Strain Range ◽  
Fatigue Life Assessment

A previously developed energy based high cycle fatigue (HCF) life assessment framework is modified to predict the low cycle fatigue (LCF) life of aluminum 6061-T6. The fatigue life assessment model of this modified framework is formulated in a closed form expression by incorporating the Ramberg–Osgood constitutive relationship. The modified framework is composed of the following entities: (1) assessment of the average strain energy density and the average plastic strain range developed in aluminum 6061-T6 during a fatigue test conducting at the ideal frequency for optimum energy calculation, and (2) determination of the Ramberg–Osgood cyclic parameters for aluminum 6061-T6 from the average strain energy density and the average plastic strain range. By this framework, the applied stress range is related to the fatigue life by a power law whose parameters are functions of the fatigue toughness and the cyclic parameters. The predicted fatigue lives are found to be in a good agreement with the experimental data.

scholarly journals A Mixed Experimental-numerical Energy-based Approach for Fatigue Life Assessment in Notched Samples under Multiaxial Loading

2020 ◽  
Author(s):  
Ricardo Branco ◽  
F. Nogueira . ◽  
D. Costa . ◽  
P. Prates . ◽  
V. Antunes .
Keyword(s):  
Fatigue Life ◽  
Energy Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Master Curve ◽  
Low Cycle Fatigue ◽  
Element Model ◽  
Multiaxial Fatigue ◽  
Life Assessment ◽  
Multiaxial Loading

This paper presents a methodology to predict the fatigue lifetime in notched geometries subjected to multiaxial loading on the basis of the cumulated strain energy density. The modus operandi consists of defining an energy-based fatigue master curve that relates the cumulated strain energy density with the number of cycles to failure using standard cylindrical specimens tested under low-cycle fatigue conditions. After that, an elastic-plastic finite-element model representative of the material behaviour, notched geometry and multiaxial loading scenario is developed and used to account for the strain energy density at the crack initiation site. This energy is then averaged using the Theory of Critical Distances and inserted into the energy- based fatigue master curve to estimate the lifetime expectancy. Overall, the comparison between the experimental and predicted fatigue lives has shown a very good agreement. Keywords: Multiaxial fatigue, Fatigue life prediction, Strain energy density

Strain Energy Approach for Axial and Torsional Fatigue Life Prediction in Aged NiCrMoV Steels

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1665-1670
Author(s):  
Gee Wook Song ◽  
Jung Seob Hyun ◽  
Jeong Soo Ha
Keyword(s):  
Fatigue Life ◽  
Energy Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Multiaxial Fatigue ◽  
Density Model ◽  
Total Strain ◽  
Total Strain Energy ◽  
Torsional Fatigue ◽  
Total Strain Energy Density

Axial and torsional low cycle fatigue tests were performed for NiCrMoV steels serviced low-pressure turbine rotor of nuclear power plant. The results were used to evaluate multiaxial fatigue life models including Tresca, von Mises and Brown and Miller's critical plane. The fatigue life predicted by the multiaxial fatigue models didn't correspond with the experimental results in small strain range. We proposed the total strain energy density model to predict torsional fatigue life from axial fatigue data. The total strain energy density model was found to best correlate the experimental data with predictions being within a factor of 2.

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