Kinetic equation of stable growth for low cycle fatigue cracks


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Abstract

Based on the analysis of the literature data on the correlation of parameters of the empirical Paris equation that links the fatigue crack growth rate (FCGR) with the stress intensity factor (SIF) range by power dependence it is established that the equation contains a latent parameter normalizing the magnitude of the SIF range, while both the parameter itself and the coefficient of proportionality between FCGR and some power of normalized SIF range are constant or slightly changing magnitudes for alloys of different types on the same basis. For reasons of dimension and symmetry analysis the nature of this parameter as well as the magnitudes of the proportionality coefficient and the index of power are determined. As a result a kinetic equation is obtained coinciding with the kinetic equation for low cycle fatigue (LCF) crack stable growth deduced earlier using a physically justified mathematical model. The same equation is obtained on the basis of experimental data that describe the LCF crack kinetics in standard specimens at the stage of crack stable growth with the use of fatigue striations as a FCGR measure. Examples of application of the kinetic equation for LCF crack stable growth modeling in aero engine disks are presented.

About the authors

N. V. Tumanov

Central Institute of Aviation Motors

Author for correspondence.
Email: tumanov@rtc.ciam.ru

Candidate of Science (Engineering)

Head of Sector

Russian Federation

References

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