Crack Growth in Titanium Alloys Under the Conjoint Action of High and Low Cycle Fatigue PDF Download
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Author: Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Fatigue crack propagation rates have been measured for two titanium-based aeroengine disc alloys using compact tension test pieces. The loading block employed simulates two features of the engine flight pattern. A major stress cycle represents the start-stop operation which leads to low cycle fatigue. In-flight vibrations, which may give rise to high cycle fatigue, are represented by superimposed minor cycles of high frequency. With a lifting policy of retirement for cause the useful lives of blades and discs are limited by the onset of minor cycle crack growth. The threshold values associated with the minor cycles have been used to predict this event. Similarly the method of linear summation has been used to predict the subsequent fatigue crack growth rates. These predictions are successful for Ti-6A1-4V, whilst for Ti-5331S they are found to be either accurate or safe. Although Ti-5331S displays a marginally greater resistance to the onset of minor cycle crack growth, of greater significance is its reduced crack growth rates prior to this event. As a consequence components fabricated from Ti-5331S will exhibit longer fatigue crack propagation lives when subjected to the conjoint action of high and low cycle fatigue.
Author: Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Fatigue crack propagation rates have been measured for two titanium-based aeroengine disc alloys using compact tension test pieces. The loading block employed simulates two features of the engine flight pattern. A major stress cycle represents the start-stop operation which leads to low cycle fatigue. In-flight vibrations, which may give rise to high cycle fatigue, are represented by superimposed minor cycles of high frequency. With a lifting policy of retirement for cause the useful lives of blades and discs are limited by the onset of minor cycle crack growth. The threshold values associated with the minor cycles have been used to predict this event. Similarly the method of linear summation has been used to predict the subsequent fatigue crack growth rates. These predictions are successful for Ti-6A1-4V, whilst for Ti-5331S they are found to be either accurate or safe. Although Ti-5331S displays a marginally greater resistance to the onset of minor cycle crack growth, of greater significance is its reduced crack growth rates prior to this event. As a consequence components fabricated from Ti-5331S will exhibit longer fatigue crack propagation lives when subjected to the conjoint action of high and low cycle fatigue.
Author: B. E. Powell Publisher: ISBN: Category : Titanium alloys Languages : en Pages : 67
Book Description
Fatigue crack propagation rates have been measured for two titanium-based aeroengine disc alloys using compact tension test pieces. The loading block employed simulates two features of the engine flight pattern. A major stress cycle represents the start-stop operation which leads to low cycle fatigue. In-flight vibrations, which may give rise to high cycle fatigue, are represented by superimposed minor cycles of high frequency. With a lifting policy of retirement for cause the useful lives of blades and discs are limited by the onset of minor cycle crack growth. The threshold values associated with the minor cycles have been used to predict this event. Similarly the method of linear summation has been used to predict the subsequent fatigue crack growth rates. These predictions are successful for Ti-6A1-4V, whilst for Ti-5331S they are found to be either accurate or safe. Although Ti-5331S displays a marginally greater resistance to the onset of minor cycle crack growth, of greater significance is its reduced crack growth rates prior to this event. As a consequence components fabricated from Ti-5331S will exhibit longer fatigue crack propagation lives when subjected to the conjoint action of high and low cycle fatigue.
Author: Theodore Nicholas Publisher: Elsevier ISBN: 0080458874 Category : Science Languages : en Pages : 657
Book Description
Dr Theodore Nicholas ran the High Cycle Fatigue Program for the US Air Force between 1995 and 2003 at Wright-Patterson Air Force Base, and is one of the world's leading authorities on the subject, having authored over 250 papers in leading archival journals and books. Bringing his plethora of expertise to this book, Dr Nicholas discusses the subject of high cycle fatigue (HCF) from an engineering viewpoint in response to a series of HCF failures in the USAF and the concurrent realization that HCF failures in general were taking place universally in both civilian and military engines. Topic covered include: - Constant life diagrams - Fatigue limits under combined LCF and HCF - Notch fatigue under HCF conditions - Foreign object damage (FOD) - Brings years of the Author's US Air Force experience in high cycle fatigue together in one text - Discusses HCF in the context of recent international military and civilian engine failures
Author: A. J. McEvily Publisher: ISBN: Category : Languages : en Pages : 13
Book Description
The report summarizes the research accomplishments in the first year's program of a study of fatigue crack growth in Ti-6Al-4V alloys. Fatigue crack growth rates have been determined in the mean threshold regions, and data for the effect of mean stress on the threshold level indicate that the dependency may be interpretable in terms of a constrant crack opening criterion. Additional work on high cycle fatigue indicates that there are two regions for the Coffin-Manson relation and that cyclically developed residual stresses may be responsible for this behavior.
Author: K.T. Rie Publisher: Springer Science & Business Media ISBN: 9400934599 Category : Technology & Engineering Languages : en Pages : 781
Book Description
In 1979 the first InternationalSymposium on Low CycleFatigue and Elasto-Plastic Behaviour of Materials was held in Stuttgart, FRG. Since then research in low cycle fatigue has proceeded rapidly. The vital interest of engineers and researchers in communicating the rapid advances in the ongoing research in low cycle fatigue has encouraged me to initiate again the Second International Conference which was held in Munich, FRG, 7-11 September 1987. Failure in low cycle fatigue represents a serious problem in the design and opera tion of highly stressed structures. Under complex loading and environmental cir cumstances, especially for high temperature services, reliable life prediction can not be expected without detailed consideration of the failure mechanism and with out extensive use of mechanistic approaches. The purpose of this conference was to provide a forum to discuss the advances in recent research in the field of low cycle fatigue. The conference was intended to help to further bridge the gap between those who are involved in basic research, and the engineers who have to perform the design of highly stressed structural components.
Author: Walter G. Reuter Publisher: ASTM International ISBN: 0803128991 Category : Languages : en Pages : 778
Book Description
Covering the whole of Asia and the Pacific region, this text provides both an analytic overview and specific data for each of the 60 countries. Introductory chapters cover regional issues, including: a regional review with the year's trends, developments and key events' analysis of the threat of terrorism in the region; the effects of deflation on the economy; the water crisis and its impact on the poor; and the successes and failures of micro-credit in the region.
Author: James M. Larsen Publisher: ISBN: Category : Aluminum alloys Languages : en Pages : 286
Book Description
An investigation was performed to study the effects of slip character and crack closure on the propagation of small fatigue cracks in titanium- aluminum alloys. The materials examined were solution-treated Ti-4Al and Ti-8Al, as well as aged Ti-8Al. The propagation of naturally initiated surface cracks of depths as small as 25 micrometers was compared with the behavior of large through-thickness cracks. An extensometer was used to monitor crack closure throughout the large crack tests, and the closure behavior of the small cracks was measured using a computerized laser interferometric displacement gage having a displacement resolution of 0.01 micrometer. The measurements of crack closure were used to compute an effective stress intensity factor range. In all three alloys and for all test conditions, which included a range of stress levels and stress ratios, small cracks propagated faster than large cracks subjected to an equivalent Delta K, and the small cracks propagated under conditions that were significantly below the large-crack threshold, Delta K(th). Although the character and distribution of slip in Ti-Al alloys may have a dramatic influence on fatigue crack initiation and on the propagation of large cracks, this effect was minimal for small cracks.
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Author: B. E. Powell
Author: Theodore Nicholas
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Author: A. J. McEvily
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Author: Josh Patrick Campbell
Author: K.T. Rie
Author: Walter G. Reuter
Author: James M. Larsen