Predicting Low-Cycle Fatigue Data for Low-Alloy Cast Steels

2009 ◽  
pp. 272-272-25 ◽  
Author(s):  
AK Schmieder
Keyword(s):  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Cast Steels ◽  
Fatigue Data ◽  
Alloy Cast

High-Temperature Fatigue Properties of Single Crystal Superalloys in Air and Hydrogen

2004 ◽  
Vol 126 (3) ◽  
pp. 590-603 ◽  
Author(s):  
N. K. Arakere
Keyword(s):  
Fatigue Life ◽  
Single Crystal ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Turbine Blades ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Fatigue Data ◽  
Blade Tip ◽  
Pressure Hydrogen

Hot section components in high-performance aircraft and rocket engines are increasingly being made of single crystal nickel superalloys such as PWA1480, PWA1484, CMSX-4, and Rene N-4 as these materials provide superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over their polycrystalline counterparts. Fatigue failures in PWA1480 single crystal nickel-base superalloy turbine blades used in the space shuttle main engine fuel turbopump are discussed. During testing many turbine blades experienced stage II noncrystallographic fatigue cracks with multiple origins at the core leading edge radius and extending down the airfoil span along the core surface. The longer cracks transitioned from stage II fatigue to crystallographic stage I fatigue propagation, on octahedral planes. An investigation of crack depths on the population of blades as a function of secondary crystallographic orientation (β) revealed that for β=45+/−15 deg tip cracks arrested after some growth or did not initiate at all. Finite element analysis of stress response at the blade tip, as a function of primary and secondary crystal orientation, revealed that there are preferential β orientations for which crack growth is minimized at the blade tip. To assess blade fatigue life and durability extensive testing of uniaxial single crystal specimens with different orientations has been tested over a wide temperature range in air and hydrogen. A detailed analysis of the experimentally determined low cycle fatigue properties for PWA1480 and SC 7-14-6 single crystal materials as a function of specimen crystallographic orientation is presented at high temperature (75°F–1800°F) in high-pressure hydrogen and air. Fatigue failure parameters are investigated for low cycle fatigue data of single crystal material based on the shear stress amplitudes on the 24 octahedral and 6 cube slip systems for FCC single crystals. The max shear stress amplitude [Δτmax] on the slip planes reduces the scatter in the low cycle fatigue data and is found to be a good fatigue damage parameter, especially at elevated temperatures. The parameter Δτmax did not characterize the room temperature low cycle fatigue data in high-pressure hydrogen well because of the noncrystallographic eutectic failure mechanism activated by hydrogen at room temperature. Fatigue life equations are developed for various temperature ranges and environmental conditions based on power-law curve fits of the failure parameter with low cycle fatigue test data. These curve fits can be used for assessing blade fatigue life.

scholarly journals Multiaxial Fatigue Life Prediction on S355 Structural and Offshore Steel Using the SKS Critical Plane Model

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1060 ◽  
Author(s):  
Alejandro Cruces ◽  
Pablo Lopez-Crespo ◽  
Belen Moreno ◽  
Fernando Antunes
Keyword(s):  
Life Prediction ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Damage Parameter ◽  
Multiaxial Fatigue ◽  
Cycle Fatigue ◽  
Critical Plane ◽  
Plane Model ◽  
Fatigue Data ◽  
Different Types

This work analyses the prediction capabilities of a recently developed critical plane model, called the SKS method. The study uses multiaxial fatigue data for S355-J2G3 steel, with in-phase and 90° out-of-phase sinusoidal axial-torsional straining in both the low cycle fatigue and high cycle fatigue ranges. The SKS damage parameter includes the effect of hardening, mean shear stress and the interaction between shear and normal stress on the critical plane. The collapse and the prediction capabilities of the SKS critical plane damage parameter are compared to well-established critical plane models, namely Wang-Brown, Fatemi-Socie, Liu I and Liu II models. The differences between models are discussed in detail from the basis of the methodology and the life results. The collapse capacity of the SKS damage parameter presents the best results. The SKS model produced the second-best results for the different types of multiaxial loads studied.

Predicting Catastrophic OD Initiated Fatigue Failure of Thick-Walled Cylinders Using Low Cycle Fatigue Data

1983 ◽  
Vol 22 ◽  
Author(s):  
Joseph A. Kapp
Keyword(s):  
Crack Growth ◽  
Fatigue Failure ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Analysis Method ◽  
Life Data ◽  
Fatigue Data ◽  
Concentration Factors ◽  
Crack Initiation Life ◽  
Stress Concentration Factors

ABSTRACTA procedure is presented to predict fatigue failure of thick-walled cylinders containing discontinuities at the OD. Both crack initiation life and crack growth are considered. The elastic-plastic strains at an OD discontinuity are estimated using an elastic analysis and stress concentration factors. The strain estimates are then used in conjunction with low cycle fatigue data to determine the initiation life. Crack growth life is estimated by integration of a power law relationship. The results obtained by using this analysis method compared to measured fatigue life data for several OD initiated failures in thick-walled cylinders agrees to within about 10 percent.

The Plastic Bending of Beams and Their Failure by Low Cycle Fatigue

1973 ◽  
Vol 95 (3) ◽  
pp. 161-169 ◽  
Author(s):  
P. K. Das ◽  
D. C. Chandler ◽  
B. K. Foster
Keyword(s):  
Large Deflection ◽  
High Strain ◽  
Low Cycle Fatigue ◽  
Rectangular Cross Section ◽  
Cyclic Strain ◽  
Cycle Fatigue ◽  
Fatigue Data ◽  
Deflection Theory ◽  
Large Deflection Theory ◽  
Bending Of Beams

The major difficulty in applying high strain fatigue data to technological problems lies not in the fatigue aspect per se but in the prediction of the cyclic strain amplitudes. In this paper they are postulated for the cyclic bending of beams using large deflection theory and taking into account the changing stress-strain relationships which occur as cycling progresses. These theories have been tested using beams of rectangular cross section made of three different materials: mild steel, stainless steel, and an aluminum alloy. Good correlation has verified their applicability.

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