Insights into the fatigue property of titanium alloy Ti-6Al-4V in aero-engine from the subsurface damages induced by milling: state of the art

Labyrinth-honeycomb seals are a state-of-the-art sealing technology commonly used in aero-engine interstage seal. The undesirable severe rub between the seal fins and the honeycomb due to the clearance change may induce the cracking of the seal fins. A pervious study investigated the wear of the seal fins at different radial incursion rates. However, due to the axial thrust and mounting clearance, the axial rub between the seal fins and the honeycomb may occur. Hence, this paper focuses on the influence of the axial rub added in the radial rub on the wear of the seal fins. The rub tests results, including rubbing forces and temperature, wear rate, worn morphology, cross-sectional morphology and energy dispersive spectroscopy results, are presented and discussed. Overall, the participation of the axial rub leads to higher rubbing forces, temperature, and wear rate. The tribo-layer on the seal fin is thicker and the cracks are more obvious at high axial incursion rate. These phenomena indicate the axial rub has a negative influence on the wear of the seal fins and should be avoided.

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Some Possible Lines of Development in Aircraft Engines

Aeronautical journal (London England 1897) ◽

10.1017/s2398187300138587 ◽

1921 ◽

Vol 25 (123) ◽

pp. 130-165

Keyword(s):

Present State ◽

State Of The Art ◽

Point Of View ◽

Aircraft Engines ◽

Aero Engine ◽

The Ideal

In the following paper the writer's aim is to indicate certain possible lines of development and research which his own investigations and preliminary experiments have shown to be at least worthy of serious consideration.If we review the present state of the art we find the position to be substantially as follows :—From a thermodynamic point of view the performance of the modern aero engine has approached so nearly to the ideal obtainable from the cycle on which it operates that there is little scope for improvement.

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On cold dwell facet fatigue in titanium alloy aero-engine components

International Journal of Fatigue ◽

10.1016/j.ijfatigue.2016.11.034 ◽

2017 ◽

Vol 97 ◽

pp. 177-189 ◽

Cited By ~ 29

Author(s):

M.A. Cuddihy ◽

A. Stapleton ◽

S. Williams ◽

F.P.E. Dunne

Keyword(s):

Titanium Alloy ◽

Aero Engine ◽

Engine Components

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Numerical Study on Fatigue Property of TC4 Titanium Alloy by Laser Shock Peening

Applied laser ◽

10.3788/al20133302.0131 ◽

2013 ◽

Vol 33 (2) ◽

pp. 131-138

Author(s):

杨晶 Yang Jing ◽

周建忠 Zhou Jianzhong ◽

黄舒 Huang Shu ◽

左立党 Zuo Lidang ◽

季杏露 Ji Xinglu ◽

...

Keyword(s):

Titanium Alloy ◽

Numerical Study ◽

Fatigue Property ◽

Laser Shock Peening ◽

Laser Shock ◽

Tc4 Titanium Alloy ◽

Shock Peening

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On the Influence of a Hubside Exducer Cavity and Bleed Air in a Close-Coupled Centrifugal Compressor Stage

Journal of Turbomachinery ◽

10.1115/1.4035606 ◽

2017 ◽

Vol 139 (7) ◽

Cited By ~ 2

Author(s):

Peter Kaluza ◽

Christian Landgraf ◽

Philipp Schwarz ◽

Peter Jeschke ◽

Caitlin Smythe

Keyword(s):

Centrifugal Compressor ◽

Pressure Field ◽

State Of The Art ◽

Test Rig ◽

Cfd Simulations ◽

Trailing Edge ◽

Loss Mechanism ◽

Aero Engine ◽

Computational Fluid Dynamics Cfd ◽

Stage Efficiency

In aero-engine applications, centrifugal compressors are often close-coupled with their respective diffusers to increase efficiency at the expense of a reduced operating range. The aim of this paper is to show that state-of-the art steady-state computational fluid dynamics (CFD) simulations can model a hubside cavity between an impeller and a close-coupled diffuser and to enhance the understanding of how the cavity affects performance. The investigated cavity is located at the impeller trailing edge, and bleed air is extracted through it. Due to geometrical limitations, the mixing plane is located in the cavity region. Therefore, the previous analyses used only a cut (“simple”) model of the cavity. With the new, “full” cavity model, the region inside the cavity right after the impeller trailing edge is not neglected anymore. The numerical setup is validated using the experimental data gathered on a state-of-the art centrifugal compressor test-rig. For the total pressure field in front of the diffuser throat, a clear improvement is achieved. The results presented reveal a drop in stage efficiency by 0.5%-points caused by a new loss mechanism at the impeller trailing edge. On the hubside, the fundamentally different interaction of the cavity with the coreflow increases the losses in the downstream components resulting in the mentioned stage efficiency drop. Finally, varying bleed air extraction is investigated with both cavity models. Only the full cavity (FC) model captures the changes measured in the experiment.

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Hot Isostatic Pressing of Titanium Alloys for Turbine Engine Components

ASME 1973 International Gas Turbine Conference and Products Show ◽

10.1115/73-gt-63 ◽

1973 ◽

Cited By ~ 1

Author(s):

G. H. Harth

Keyword(s):

Mechanical Properties ◽

Titanium Alloy ◽

Powder Processing ◽

State Of The Art ◽

Hot Isostatic Pressing ◽

Turbine Engine ◽

Isostatic Pressing ◽

Powder Consolidation ◽

Powder Type ◽

Engine Components

This paper presents the state-of-the-art knowledge concerning the application of powder metallurgy to the fabrication of titanium alloy turbine engine components. The effect of powder type, powder processing, and method of powder consolidation on the mechanical properties and microstructures of P/M parts it discussed. The advantages of using hot isostatic pressing (HIP) in producing engine components is outlined.

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Experimental Study on Fatigue Crack Growth in a Titanium Alloy

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.297-300.2489 ◽

2005 ◽

Vol 297-300 ◽

pp. 2489-2494

Author(s):

Qing Fen Li ◽

Peng Wang ◽

Dong Liu ◽

Jun Wang ◽

Hong Juan Liu ◽

...

Keyword(s):

Growth Rate ◽

Titanium Alloy ◽

Fatigue Crack ◽

Crack Growth Rate ◽

Fatigue Crack Growth ◽

Crack Growth ◽

Welded Joint ◽

Fatigue Property ◽

Rolled Ring ◽

Titanium Material

A series of test for the fatigue crack growth rate da/dN and the threshold ΔKth values were performed with CT specimens on a ship-condenser material titanium alloy plate and rolled ring. Base metal, welded joint and HAZ (heat affected zone) materials were used to make different test specimens. Specimens made from the titanium plate were cut along L-T direction, those made from rolled ring were obtained along C-R and L-R direction respectively. Results show that the fatigue crack growth rate value of welded joint is much higher than those of base metal and HAZ material. The da/dN values of C-R direction specimens are much higher than those of L-R direction specimens, whereas the ΔKth values are lower. It means that welding process may lead to a great reduction in the fatigue property for titanium alloy and the effect of crack orientation on fatigue property is not negligible for titanium alloy. To select a proper orientation of titanium material is therefore very important in engineering practice. Results also indicate that a simplified method can be used to calculate the ΔKth values for titanium material, that is, ΔKth values may be calculated directly from the da/dN expression in a zone near the threshold and the laborious measurements of ΔKth may therefore be saved.

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An Update on Nickel-Titanium Rotary Instruments in Endodontics: Mechanical Characteristics, Testing and Future Perspective—An Overview

Bioengineering ◽

10.3390/bioengineering8120218 ◽

2021 ◽

Vol 8 (12) ◽

pp. 218

Author(s):

Alessio Zanza ◽

Maurilio D’Angelo ◽

Rodolfo Reda ◽

Gianluca Gambarini ◽

Luca Testarelli ◽

...

Keyword(s):

Mechanical Properties ◽

Titanium Alloy ◽

Mechanical Characteristics ◽

State Of The Art ◽

Cyclic Fatigue ◽

Nickel Titanium ◽

Future Perspective ◽

Current State ◽

Rotary Instruments ◽

Torsional Loads

Since the introduction of Nickel-Titanium alloy as the material of choice for the manufacturing of endodontic rotary instruments, the success rate of the root canal therapies has been significantly increased. This success mainly arises from the properties of the Nickel-Titanium alloy: the biocompatibility, the superelasticity and the shape memory effect. Those characteristics have led to a reduction in time of endodontic treatments, a simplification of instrumentation procedures and an increase of predictability and effectiveness of endodontic treatments. Nevertheless, the intracanal separation of Nickel-Titanium rotary instruments is still a major concern of endodontists, with a consequent possible reduction in the outcome rate. As thoroughly demonstrated, the two main causes of intracanal separation of endodontic instruments are the cyclic fatigue and the torsional loads. As results, in order to reduce the percentage of intracanal separation research and manufacturers have been focused on the parameters that directly or indirectly influence mechanical properties of endodontic rotary instruments. This review describes the current state of the art regarding the Nickel-Titanium alloy in endodontics, the mechanical behavior of endodontic rotary instruments and the relative stresses acting on them during intracanal instrumentation, highlighting the limitation of the current literature.

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