Abstract
We present a modified energy-principle based model of fatigue damage accumulation in high temperature alloys usually used in gas turbine engine under combined high cycle fatigue and low cycle fatigue (LCF/HCF) loading conditions. Our model is based on the energy principle which includes a modified approximation formula that describes fatigue crack origin depending on the relative amplitude of stress intensity in the ranges of both high- and low-cycle fatigue under non-isothermal loading. Functional dependence that presents the influence of HCF mechanisms on a fatigue life of our structural material is gradual and it has not breaks of the curve that yields a possibility to rewrite the equation of the S-N curve with taking into account combined cycle fatigue loading. We used the same number of parameters as the initial model. Note, that new parameter interpretation gives clear physical picture. The proposed model is verified by comparing the computed results with the experimental data for one high temperature alloy GH4133.
Highlights
The regime named as a combined cycle fatigue (CCF) is one of the main challenges of the modern fatigue damage analysis and its analysis is a rather complex problem
We propose a modified formula for the function that describes the mechanism of influence of cycle loading on a fatigue life of our structural material
The aim of current research was to present a modified energy-principle based model of fatigue damage accumulation in high temperature alloys usually used in gas turbine engine under combined high cycle fatigue and low cycle fatigue loading conditions
Summary
The regime named as a combined cycle fatigue (CCF) is one of the main challenges of the modern fatigue damage analysis and its analysis is a rather complex problem. MATEC Web of Conferences like to discuss one of new methods those attempt to combine LCF and HCF and develop CCF approach based on the special representation of the specific energy of cycle deformation as a damage parameter. In the energy-based approach it is assumed that the limit state of a material is determined by that value of the mechanical energy which was dissipated irreversible at cycle deformation. Some part of this energy will be spending on the fatigue crack origin. We propose a modified formula for the function that describes the mechanism of influence of cycle loading on a fatigue life of our structural material
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