A Theoretical Study of Residual Stress Effects on Fatigue Life Prediction

2001 ◽  
Vol 44 (4) ◽  
pp. 609-614 ◽  
Author(s):  
Michael N. Kotzalas
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Life Prediction ◽  
Theoretical Study ◽  
Fatigue Life Prediction ◽  
Stress Effects

Fatigue Life Prediction for Complex Load Versus Time Histories

1983 ◽  
Vol 105 (3) ◽  
pp. 206-214 ◽  
Author(s):  
N. E. Dowling
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Constant Amplitude ◽  
Discrete Events ◽  
Complex Load ◽  
Stress Effects ◽  
Fatigue Data ◽  
Time Histories ◽  
Damage Type

Fatigue life prediction for complex load versus time histories is considered from the viewpoint of separating the history into discrete events, or cycles, which may then be used with constant amplitude fatigue data in a cumulative damage type of analysis. Highly irregular histories require special attention, with minor load excursions being considered in cycle counting as temporary interruptions of larger load cycles. Local notch plasticity and mean stress effects are interrelated, and such effects are most rationally accounted for in terms of local notch stresses and strains. The paper describes and discusses a life prediction procedure for notched members which is based on modeling of the stresses and strains occurring locally at the notch.

The Ability of Current Models for Fatigue Life Prediction of Shot Peened Components

2009 ◽  
Vol 417-418 ◽  
pp. 901-904 ◽  
Author(s):  
Ricardo A. Cláudio ◽  
José M. Silva ◽  
Carlos M. Branco ◽  
Jim Byrne
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Fracture Mechanics ◽  
Shot Peening ◽  
Life Prediction ◽  
Compressive Residual Stress ◽  
Prediction Models ◽  
Critical Distance ◽  
Fatigue Life Prediction ◽  
Distance Methods

It is well known that shot peening has a marked benefit on fatigue life for the majority of applications. This effect is attributed mainly due to the compressive residual stress state at the component’s surface due to shot peening. The present paper evaluates the ability of several fatigue life prediction models, commonly used for general analyses, to predict the behaviour of components with compressive residual stress due to shot peening. Advanced elastic-plastic finite element analyses were carried out in order to obtain stress, strain, strain energy and fracture mechanics parameters for cracks within a compressive residual stress field. With these results several total fatigue life prediction models (including critical distance methods) and fracture mechanics based models were applied in order to predict fatigue life. Fatigue life predictions were compared with several experimental fatigue tests carried out on specimens, representative of a critical region of a compressor disc in a gas turbine aero engine. The results obtained showed that total fatigue life methods, even if combined with critical distance methods, give conservative results when shot peening is considered. Fatigue life was successfully predicted using the method proposed by Cameron and Smith, by adding initiation life to crack propagation life. This last method was also successfully applied for the prediction of non-propagating cracks that were observed during the experimental tests.

Fatigue Life Prediction of an Autofrettaged Thick-Walled Pressure Vessel With an External Groove

1991 ◽  
Vol 113 (3) ◽  
pp. 368-374 ◽  
Author(s):  
S. K. Koh ◽  
R. I. Stephens
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Pressure Vessel ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Fatigue Life Prediction ◽  
Mean Stress ◽  
Cycle Fatigue ◽  
Operating Stress

An autofrettaged thick-walled pressure vessel with an external groove subjected to a pulsating internal pressure can have fatigue failures at the external groove root due to the combination of tensile autofrettage residual stress, operating stress, and stress concentration. To predict the fatigue life of the autofrettaged thick-walled pressure vessel with an external groove, the local strain approach was applied. The residual stress distribution due to autofrettage and the operating stress distribution due to internal pressure were determined using finite element analysis which resulted in theoretical stress concentration factors. To account for the mean stress effects on the fatigue life prediction of the pressure vessel, low-cycle fatigue behavior with several strain ratios was obtained using smooth axial specimens taken from the ASTM A723 thick-walled steel pressure vessel. Fatigue life predictions were made by incorporating the local strains determined from the linear rule and Neuber’s rule and the Morrow and SWT mean stress parameters determined from low-cycle fatigue tests. The predicted fatigue lives were within factors of 2 to 4, compared to simulated experimental fatigue lives based upon fatigue cracks of 2.5 mm in length. These procedures appear to be realistic for evaluating fatigue lives for this complex pressure vessel.

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