Probabilistic fatigue life prediction of an aero-engine turbine shaft

Abstract

Purpose Aero-engine components endure combined high and low cycle fatigue (CCF) loading during service, which has attracted more research attention in recent years. This study aims to construct a new framework for the prediction of probabilistic fatigue life and reliability evaluation of an aero-engine turbine shaft under CCF loading if considering the material uncertainty. Design/methodology/approach To study the CCF failure of the aero-engine turbine shaft, a CCF test is carried out. An improved damage accumulation model is first introduced to predict the CCF life and present high prediction accuracy in the CCF loading situation based on the test. Then, the probabilistic fatigue life of the turbine shaft is predicted based on the finite element analysis and Monte Carlo analysis, where the material uncertainty is taken into account. At last, the reliability evaluation of the turbine shaft is conducted by stress-strength interference models based on an improved damage accumulation model. Findings The results indicate that predictions agree well with the tested data. The improved damage accumulation model can accurately predict the CCF life because of interaction damage between low cycle fatigue loading and high cycle fatigue loading. As a result, a framework is available for accurate probabilistic fatigue life prediction and reliability evaluation. Practical implications The proposed framework and the presented testing in this study show high efficiency on probabilistic CCF fatigue life prediction and can provide technical support for fatigue optimization of the turbine shaft. Originality/value The novelty of this work is that CCF loading and material uncertainty are considered in probabilistic fatigue life prediction.

Fatigue Analysis of a Cracked Shaft: a Finite Element Modeling Approach

“…Cracks on a surface not only reduce the strength of the material through the deduction in the crosssection thickness but also readily propagate the material through stress concentration at the tip under cyclic loading [3]. Crack formation on engineering components and structures occurs due to continuous stress on the subject especially on the rotating structure like shaft [4]- [6]. Thus, the shafts that are condoned to undergo cyclic loading over a prolonged period which may lead to metal fatigue [7].…”

A reliability analysis and optimization method for a turbine shaft under combined high and low cycle fatigue loading

“…Turbine shafts experience a hybrid loading of axial force, torque and bending moment. The axial force and torque are with high amplitude and low frequency, which is called low cycle fatigue (LCF) loads, and the bending moment is with low amplitude and high frequency, which is called high cycle fatigue (HCF) loads 5,6 . The HCF loads are superimposed upon the LCF load, leading to a phenomenon termed combined high and low cycle fatigue (CCF), which significantly impacts the structural integrity and durability of these components 7,8 .…”

“…The axial force and torque are with high amplitude and low frequency, which is called low cycle fatigue (LCF) loads, and the bending moment is with low amplitude and high frequency, which is called high cycle fatigue (HCF) loads. 5,6 The HCF loads are superimposed upon the LCF load, leading to a phenomenon termed combined high and low cycle fatigue (CCF), which significantly impacts the structural integrity and durability of these components. 7,8 Consequently, comprehensive consideration of the CCF loading spectrum is imperative in the reliability analysis [9][10][11] and design 12 of turbine shafts.…”