Prediction of Crack Growth Life for Aircraft Engine Disks under Creep-Fatigue Loading Condition(Strength & Fracture)

2001 ◽  
Vol 1.01.203 (0) ◽  
pp. 333-338
Author(s):  
Seung Hoon Nahm ◽  
Jonghwa Park ◽  
Jong Yup Kim ◽  
Yiu-Wing Mai
Keyword(s):  
Crack Growth ◽  
Loading Condition ◽  
Aircraft Engine ◽  
Fatigue Loading ◽  
Creep Fatigue

Crack Growth in Stainless Steel 304 under Creep-Fatigue Loading

2007 ◽  
Vol 353-358 ◽  
pp. 485-490 ◽  
Author(s):  
Y.M. Baik ◽  
K.S. Kim
Keyword(s):  
Stress Intensity Factor ◽  
Stainless Steel ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Growth ◽  
Growth Rates ◽  
Static Loading ◽  
Fatigue Loading ◽  
Creep Fatigue ◽  
Crack Growth Rates

Crack growth in compact specimens of type 304 stainless steel is studied at 538oC. Loading conditions include pure fatigue loading, static loading and fatigue loading with hold time. Crack growth rates are correlated with the stress intensity factor. A finite element analysis is performed to understand the crack tip field under creep-fatigue loading. It is found that fatigue loading interrupts stress relaxation around the crack tip and cause stress reinstatement, thereby accelerating crack growth compared with pure static loading. An effort is made to model crack growth rates under combined influence of creep and fatigue loading. The correlation with the stress intensity factor is found better when da/dt is used instead of da/dN. Both the linear summation rule and the dominant damage rule overestimate crack growth rates under creep-fatigue loading. A model is proposed to better correlate crack growth rates under creep-fatigue loading: 1 c f da da da dt dt dt Ψ −Ψ     =         , where Ψ is an exponent determined from damage under pure fatigue loading and pure creep loading. This model correlates crack growth rates for relatively small loads and low stress intensity factors. However, correlation becomes poor as the crack growth rate becomes large under a high level of load.

Inelastic FE Analysis for J-Integral of Center-Cracked Plate in Creep-Fatigue Range

2014 ◽  
Author(s):  
Madoka Funai ◽  
Osamu Watanabe ◽  
Akihiro Matsuda
Keyword(s):  
Crack Growth ◽  
Creep Crack Growth ◽  
Creep Damage ◽  
Fatigue Loading ◽  
Fe Analysis ◽  
Creep Process ◽  
J Integral ◽  
Fatigue Process ◽  
Cracked Plate ◽  
Creep Fatigue

In order to estimate crack growth rate, it is necessary to use increments of the J-integral for both of time-independent fatigue process and time-dependent creep process. Many researchers and methodologies use C* to characterize creep crack growth and ΔJ or ΔK for fatigue crack growth, suggested are the following Refs.[1,2] This paper shows the fundamental features of J-integral in elastic, plastic and creep range. The path dependency is studied for center-cracked plate by using path integral from the large path to the small path near crack tip. The inelastic FE analysis is carried out for creep-fatigue loading, where the tensile strain is held constant to receive creep damage, and this paper shows the J-integral according to the loading histories. Also discussed are effects of the strain rate in fatigue process to affect the successive creep behavior.

Evaluating the Critical Temperature of Creep-Fatigue Interaction a Nickel-Based Powder Metallurgy Superalloy

2013 ◽  
Vol 577-578 ◽  
pp. 625-628
Author(s):  
Hao Liu ◽  
Rui Bao ◽  
Wei Ming Lei ◽  
Bin Jun Fei
Keyword(s):  
Fatigue Crack ◽  
Critical Temperature ◽  
Powder Metallurgy ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Elevated Temperatures ◽  
Fatigue Loading ◽  
Damage Mechanism ◽  
Creep Fatigue ◽  
Creep Fatigue Crack

For the components working in high temperature and enduring fatigue loading, the fatigue fracture properties will be reduced remarkably when the working temperature is higher than the critical temperature of creep-fatigue interactionTcof the material. In consequence, the damage mechanism from creep-fatigue interaction becomes more complex. A method is presented in this paper to determine theTcof a nickel-based powder metallurgy superalloy. Pure fatigue crack growth and creep-fatigue crack growth tests were conducted in several different elevated temperatures. The fracture mechanism was investigated via observing the fractographic characteristics using scanning electron microscope (SEM). The test results show that theTcof this superalloy is a little bit lower than a half of the melting temperatureTm.

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