Implications of Day Temperature for a High-Pressure-Turbine Blade's Low-Cycle-Fatigue Life Consumption

2008 ◽  
Vol 24 (3) ◽  
pp. 624-628 ◽  
Author(s):  
Muhammad Naeem
Keyword(s):  
High Pressure ◽  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
High Pressure Turbine ◽  
Life Consumption

Implications of Turbine Erosion for an Aero-Engine’s High-Pressure-Turbine Blade’s Low-Cycle-Fatigue Life-Consumption

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Muhammad Naeem
Keyword(s):  
High Pressure ◽  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Life Cycle Costs ◽  
Cycle Fatigue ◽  
Mechanical Device ◽  
High Pressure Turbine ◽  
Aero Engine ◽  
Life Consumption ◽  
Mission Profile

Some in-service deterioration in any mechanical device, such as a military aero-engine, is inevitable. As a result of experiencing any deterioration, an aero-engine will seek a different steady operating point thereby resulting in a variation in the high-pressure spool speeds in order to provide the same thrust to keep aircraft’s performance invariant. Any increase in the high-pressure spool speed results in greater low-cycle fatigue damage for the hot-end components and thereby higher engine’s life-cycle costs. Possessing better knowledge (of the impacts of high-pressure turbine’s erosion upon the low-cycle fatigue life-consumption of aero-engine’s hot-end components) helps the users to take wiser management decisions. For a military aircraft’s mission profile, using bespoke computer simulations, the impacts of turbine erosion for high-pressure turbine-blade’s low-cycle fatigue life-consumption have been predicted.

A Novel Experimental Method for LCF Measurement of Nickel Base Super Alloys in High Pressure High Temperature Supercritical CO2

2017 ◽  
Author(s):  
Azam Thatte ◽  
Etienne Martin ◽  
Tim Hanlon
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Conversion Efficiency ◽  
Supercritical Co2 ◽  
Low Cycle Fatigue ◽  
Total Power ◽  
Cycle Fatigue ◽  
High Pressure High Temperature

CSP plants using supercritical CO2 (sCO2) power cycle can potentially achieve high thermal conversion efficiency at low capital cost due to compact turbomachinery and other components. An sCO2 expander and improved heat exchanger is expected to provide a major stepping stone for achieving CSP power at $0.06/kW-hr LCOE, energy conversion efficiency > 50%, and total power block cost < $1,200/kW installed. However the life limiting mechanisms of these turbomachines in high pressure, high temperature sCO2 environment are not well understood. To understand the effect of high pressures, high temperatures and sCO2 chemical kinetics on crack initiation, crack propagation and low cycle fatigue (LCF) life of these turbomachines, a novel experimental setup is developed. Advanced microstructure and spectroscopic analyses are conducted that shed light on some key differences between various Ni base alloys in terms of oxidation morphology, chemical species diffusion and trapping, the formation of protective corrosion resistant layers and changes in surface properties. An experimental technique for low cycle fatigue experiments in high pressure, high temperature supercritical CO2 environment is developed. The test setup allows for pressurized LCF testing of alloys being considered for MW scale sCO2 turbine development. Results show that the LCF life remains the same (within the scatter band) irrespective of the location of crack initiation site whether at the OD (non shot-peened bars in air and sCO2), or at the ID (shot peened bars). Total fatigue life, for all conditions, lie within the normal variation in LCF results (± 2X life variation). No significant LCF life debit is observed in IN718 by sCO2 at 550 °C, 0.7% max strain, 20 cpm. Similar conclusion is reached during 0.6% max strain tests. The effect of sCO2 is found not to be significantly more damaging than air at these strain levels. However, the results can be different for lower % max strains due to longer exposure times involved, resulting from larger number of cycles to failure. Similarly at higher temperatures and/or longer hold-times, sCO2 environment may be more aggressive, resulting in lower total fatigue life.

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.

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