Author: Stephan M. RussPublisher:
ISBN:
Category :
Languages : en
Pages : 271
Book Description
Effect of Underloads on Fatigue Crack Growth of Titanium-17
Author: Stephan M. RussThe Effect of Load Excursions on Fatigue Crack Growth in a Titanium Alloy
Author: David Eugene LemmThe Effect of O2, H2O, and N2 on the Fatigue Crack Growth Behavior of an Alpha + Beta Titanium Alloy at 24 C and 177 C
Author: Stephen W. SmithThe Effects of Slip Character and Crack Closure on the Growth of Small Fatigue Cracks in Titanium-aluminium Alloys
Author: James M. LarsenPublisher:
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.
Fatigue Crack Growth Characteristics of Thin Sheet Titanium Alloy Ti 6-2-2-2-2
Author: National Aeronautics and Space Adm NasaPublisher: Independently Published
ISBN: 9781723951589
Category : Science
Languages : en
Pages : 76
Book Description
Fatigue crack growth rates of Ti 6-2-2-2-2 as a function of stress ratio, temperature (24 or 177 C), tensile orientation and environment (laboratory air or ultrahigh vacuum) are presented. Fatigue crack growth rates of Ti 6-2-2-2-2 are also compared with two more widely used titanium alloys (Timetal 21S and Ti 6Al-4V). The fatigue crack growth rate (da/dN) of Ti 6-2-2-2-2 in laboratory air is dependent upon stress ratio (R), particularly in the near-threshold and lower-Paris regimes. For low R (less than approximately 0.5), da/dN is influenced by crack closure behavior. At higher R (> 0.5), a maximum stress-intensity factor (K(sub max)) dependence is observed. Fatigue crack growth behavior is affected by test temperature between 24 and 177 C. For moderate to high applied cyclic-stress-intensity factors (delta-K), the slope of the log da/dN versus log delta-K curve is lower in 177 C laboratory air than 24 C laboratory air. The difference in slope results in lower values of da/dN for exposure to 177 C laboratory air compared to room temperature laboratory air. The onset of this temperature effect is dependent upon the applied R. This temperature effect has not been observed in ultrahigh vacuum. Specimen orientation has been shown to affect the slope of the log da/dN versus log delta-K curve in the Paris regime.Smith, Stephen W. and Piascik, Robert S.Langley Research CenterCRACK PROPAGATION; FATIGUE (MATERIALS); TITANIUM ALLOYS; CORROSION; STRESS RATIO; TEMPERATURE EFFECTS; CRACK CLOSURE; STRESS INTENSITY FACTORS
Fatigue Crack Growth Under Spectrum Loads
Author: Ralph Ivan StephensPublisher: ASTM International
ISBN:
Category : Alloys
Languages : en
Pages : 345
Book Description
Overload and Underload Effects on the Fatigue Crack Growth Behavior of the 2024-T3 Aluminum Alloy
Author: Fatigue-crack Propagation in Several Titanium and Stainless-steel Alloys and One Superalloy
Author: C. M. HudsonPublisher:
ISBN:
Category : Materials at high temperatures
Languages : en
Pages : 40
Book Description
Fatigue Crack Growth Characteristics of Thin Sheet Titanium Alloy Ti 6-2-2-2-2
Author: Crack Growth in Titanium Alloys Under 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.