Aeromechanical Modeling of Rotating Fan Blades to Investigate High-Cycle and Low-Cycle Fatigue Interaction

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Priyanka Dhopade ◽  
Andrew J. Neely
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Low Cycle Fatigue ◽  
Numerical Approach ◽  
Combined Loading ◽  
Design Stage ◽  
Cycle Fatigue ◽  
Mechanics Analysis ◽  
The Individual ◽  
Loading Spectrum

Gas turbine engine components are subject to both low-cycle fatigue (LCF) and high-cycle fatigue (HCF) loads. To improve engine reliability, durability and maintenance, it is necessary to understand the interaction of LCF and HCF in these components, which can adversely affect the overall life of the engine while they are occurring simultaneously during a flight cycle. A fully coupled aeromechanical fluid–structure interaction (FSI) analysis in conjunction with a fracture mechanics analysis was numerically performed to predict the effect of representative fluctuating loads on the fatigue life of blisk fan blades. This was achieved by comparing an isolated rotor (IR) to a rotor in the presence of upstream inlet guide vanes (IGVs). A fracture mechanics analysis was used to combine the HCF loading spectrum with an LCF loading spectrum from a simplified engine flight cycle in order to determine the extent of the fatigue life reduction due to the interaction of the HCF and LCF loads occurring simultaneously. The results demonstrate the reduced fatigue life of the blades predicted by a combined loading of HCF and LCF cycles from a crack growth analysis, as compared to the effect of the individual cycles. In addition, the HCF aerodynamic forcing from the IGVs excited a higher natural frequency of vibration of the rotor blade, which was shown to have a detrimental effect on the fatigue life. The findings suggest that FSI, blade–row interaction and HCF/LCF interaction are important considerations when predicting blade life at the design stage of the engine. The lack of available experimental data to validate this problem emphasizes the utility of a numerical approach to first examine the physics of the problem and second to help establish the need for these complex experiments.

Aeromechanical Modelling of Fan Blades to Investigate High-Cycle and Low-Cycle Fatigue Interaction

2014 ◽  
Author(s):  
Priyanka Dhopade ◽  
Andrew J. Neely
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Low Cycle Fatigue ◽  
Combined Loading ◽  
Design Stage ◽  
Cycle Fatigue ◽  
Turbine Engine ◽  
Mechanics Analysis ◽  
The Individual ◽  
Loading Spectrum

Gas turbine engine components are subject to both low-cycle fatigue (LCF) and high-cycle fatigue (HCF) loads. To improve engine reliability, durability and maintenance, it is necessary to understand the interaction of LCF and HCF in these components, which can adversely affect the overall life of the engine while they are occurring simultaneously during a flight cycle. A fully coupled aeromechanical fluid-structure interaction (FSI) analysis in conjunction with a fracture mechanics analysis was numerically performed to predict the effect of representative fluctuating loads on the fatigue life of blisk fan blades. This was achieved by comparing an isolated rotor to a rotor in the presence of upstream inlet guide vanes (IGVs). A fracture mechanics analysis was used to combine the HCF loading spectrum with an LCF loading spectrum from a simplified engine flight cycle in order to determine the extent of the fatigue life reduction due to the interaction of the HCF and LCF loads occurring simultaneously. The results demonstrate the reduced fatigue life of the blades predicted by a combined loading of HCF and LCF cycles from a crack growth analysis, as compared to the effect of the individual cycles. In addition, the HCF aerodynamic forcing from the IGVs excited a higher natural frequency of vibration of the rotor blade, which was shown to have a detrimental effect on the fatigue life. The findings suggest that FSI, blade-row interaction and HCF/LCF interaction are important considerations when predicting blade life at the design stage of the engine.

Prediction of the low cycle fatigue regime of the S–N curve with application to an aluminium alloy

2011 ◽  
Vol 226 (5) ◽  
pp. 1198-1209 ◽  
Author(s):  
M M Jan ◽  
H-P Gaenser ◽  
W Eichlseder
Keyword(s):  
Fatigue Life ◽  
Aluminium Alloy ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Life Time ◽  
High Loading ◽  
Design Stage ◽  
Cycle Fatigue ◽  
Static Properties ◽  
Design Engineers

Engineering estimates for the prediction of fatigue life is an important consideration at the design stage of components. Conventional approach of dimensioning against cyclic loading consists of comparing the stress amplitudes against the life time. Similarly, when a component is under high loading, a strain-life methodology is adopted. In both cases, extensive experimental efforts are required for obtaining the stress-life or strain-life curves. Therefore, it is important to develop a methodology for obtaining the fatigue life of a material to obtain a basic fatigue life data for design engineers. This study focuses on the fatigue life of a material in the region of low cycle fatigue. A method is proposed for obtaining an estimate for the fatigue life of material under high loading from the results of the high cycle fatigue and static properties of the material within the stress-based diagram. The concept is applied to a wrought aluminium alloy typically used for cryogenic applications.

Fracture mechanics analysis method for cracked components under very low cycle fatigue loading

2020 ◽  
Vol 188 ◽  
pp. 104191
Author(s):  
Gyo-Geun Youn ◽  
Jin-Ha Hwang ◽  
Dae-Young Lee ◽  
Yun-Jae Kim ◽  
Jin-Weon Kim ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Low Cycle Fatigue ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Analysis Method ◽  
Mechanics Analysis

Low-Cycle Fatigue Performance of Buckling Restrained Braces and Assessment of Cumulative Damage under Severe Earthquakes

2018 ◽  
Vol 763 ◽  
pp. 867-874
Author(s):  
Yu Shu Liu ◽  
Ke Peng Chen ◽  
Guo Qiang Li ◽  
Fei Fei Sun
Keyword(s):  
Fatigue Life ◽  
Energy Dissipation ◽  
Structural Reliability ◽  
Low Cycle Fatigue ◽  
Engineering Application ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Variable Amplitude ◽  
Buckling Restrained Braces ◽  
Energy Dissipation Devices

Buckling Restrained Braces (BRBs) are effective energy dissipation devices. The key advantages of BRB are its comparable tensile and compressive behavior and stable energy dissipation capacity. In this paper, low-cycle fatigue performance of domestic BRBs is obtained based on collected experimental data under constant and variable amplitude loadings. The results show that the relationship between fatigue life and strain amplitude satisfies the Mason-Coffin equation. By adopting theory of structural reliability, this paper presents several allowable fatigue life curves with different confidential levels. Besides, Palmgren-Miner method was used for calculating BRB cumulative damages. An allowable damage factor with 95% confidential level is put forward for assessing damage under variable amplitude fatigue. In addition, this paper presents an empirical criterion with rain flow algorithm, which may be used to predict the fracture of BRBs under severe earthquakes and provide theory and method for their engineering application. Finally, the conclusions of the paper were vilified through precise yet conservative prediction of the fatigue failure of BRB.

scholarly journals Fatigue Testing of Wearable Sensing Technologies: Issues and Opportunities

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4070
Author(s):  
Andrea Karen Persons ◽  
John E. Ball ◽  
Charles Freeman ◽  
David M. Macias ◽  
Chartrisa LaShan Simpson ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Prediction Models ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Wearable Sensors ◽  
Fatigue Tests ◽  
Proof Of Concept ◽  
Cycle Fatigue ◽  
Wearable Sensing ◽  
Failure Data

Standards for the fatigue testing of wearable sensing technologies are lacking. The majority of published fatigue tests for wearable sensors are performed on proof-of-concept stretch sensors fabricated from a variety of materials. Due to their flexibility and stretchability, polymers are often used in the fabrication of wearable sensors. Other materials, including textiles, carbon nanotubes, graphene, and conductive metals or inks, may be used in conjunction with polymers to fabricate wearable sensors. Depending on the combination of the materials used, the fatigue behaviors of wearable sensors can vary. Additionally, fatigue testing methodologies for the sensors also vary, with most tests focusing only on the low-cycle fatigue (LCF) regime, and few sensors are cycled until failure or runout are achieved. Fatigue life predictions of wearable sensors are also lacking. These issues make direct comparisons of wearable sensors difficult. To facilitate direct comparisons of wearable sensors and to move proof-of-concept sensors from “bench to bedside,” fatigue testing standards should be established. Further, both high-cycle fatigue (HCF) and failure data are needed to determine the appropriateness in the use, modification, development, and validation of fatigue life prediction models and to further the understanding of how cracks initiate and propagate in wearable sensing technologies.

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