Mechanistically-based probabilistic methods for the prediction of fatigue damage

Soboyejo, W. O.; Rabeeh, Bakr Mohamed; Li, Y.; Soboyejo, A. B. O.

doi:10.2514/6.1997-1133

Cited by 8 publications

(15 citation statements)

References 12 publications

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“…Hall-Petch behavior is apparent in both the LO and NO alloys at both room-and elevated-temperature. Similar Hall-Petch behavior has been reported by other investigators (14)(15)(16)(17) for other gamma alloys. However, there is some scatter in the NO data at room-temperature, especially in tlie small grain size regime (Figure 3b).…”

Section: Effects Of Interstitial Oxygcn On Ti-48aisupporting

confidence: 91%

On the Influence of Microstructure on the Fracture Behavior of Gamma-Based Titanium Aluminides. III. Effects of Interstitials and Microalloying with W

Soboyejo

Mercer

1996

Materials and Manufacturing Processes

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The results of a recent study of the effects of interstitial elements and microalloying with 11.2 at.% W on the tensile and fracture properties of Ti-48AI (compositions quoted in atomic % unless stated otherwise) base gamma alloys are presented in this paper. Lower interstitial oxygen levels are shown to promote higher levels of tensile ductility at the expense of yieldlultimate tensile strength and fracture toughness. Microalloying with W is also shown to result in microstructural instability and a concomitant degradation in tensile and fracture properties. Ductility and yieldlultimate tensile strengths in binary gamma alloys at room-and elevilled-te~nperature are shown to exhibit a simple Hall-Petch dependence on the average grainllamellar packet size. The observed Hall-Petch behavior is found t c~ be independent of lamellar volume fraction and fracture mechanism at room.. and elevated-temperature. The implications of the results are discussed for fut~~re alloylprocess development.

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Section: Effects Of Interstitial Oxygcn On Ti-48aisupporting

confidence: 91%

On the Influence of Microstructure on the Fracture Behavior of Gamma-Based Titanium Aluminides. III. Effects of Interstitials and Microalloying with W

Soboyejo

Mercer

1996

Materials and Manufacturing Processes

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“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] It has been suggested that a composite undergoes carbide fibers (diameter of Ϸ140 m) produced by Textron elastic deformation of the composite, interfacial debonding, Specialty Material Division (Lowell, MA), hipped at a temmatrix elastic deformation after interfacial debonding, perature of approximately 900 ЊC. The 1140ϩ/Ti-6-4 commatrix plastic deformation, and final catastrophic failure posites were received in the form of a 12-ply plate with a under tensile loading.…”

Section: Introductionmentioning

confidence: 99%

Transverse behavior and acoustic-emission analysis of titanium metal-matrix composites under tensile loading

Wu¹,

Mori

Bowen

2001

Metall Mater Trans A

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The transverse behavior of 1140ϩ/Ti-6-4 and SCS-6/Ti-␤21s composites has been investigated using conventional tensile testing in air. Acoustic emission (AE) has also been used to assess and to locate the position of damage. Few AE events can be detected in 1140ϩ/Ti-6-4 composites below the stress of ϳ250 MPa, whereas for SCS-6/Ti-␤21s composites, AE events are found almost immediately on loading. Many AE events of high energy were detected over a range of stresses, which appear to be associated with debonding. Continuous AE events are obtained with an increase of stress, and this suggests that debonding is an incremental process: a ring crack (formed by premature debonding at the surface) penetrates into the depth along interface "tubes." The peak energy of AE events obtained in SCS-6/Ti-␤21s composites is ϳ650 arbitrary units, which is approximately 4 times that obtained in 1140ϩ/Ti-6-4 composites. Distinct AE events have also been deduced to correspond to cracking of carbon coating layers and fiber/matrix reaction products. A change of fiber volume fraction from 8 to 21 pct for the 1140ϩ/Ti-6-4 composites has no effect on the characteristics or distribution of AE events received.

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“…These studies researched various TMCs under load and temperature variations that ranged from simple constant-amplitude fatigue [1] to very complex hypersonic flight profiles. [2] There have also been studies dealing with crack growth, [3,4] micromechanical properties, [5,6] and the effect of vacuum exposure, [7] to name a few. Although a large amount of work has been performed on several TMC systems, there has been very little attention devoted to residual strength degradation [8,9] (defined as the remaining tensile strength after exposure to cyclic loading).…”

Section: Introductionmentioning

confidence: 99%

Degradation of residual strength in SCS-6/Ti-15-3 Due to fully reversed fatigue

Calcaterra¹,

Mall

Coghlan³

1999

Metall Mater Trans A

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Little attention has been given to residual strength degradation in titanium matrix composites (TMCs) after exposure to fatigue loading. To address this problem, fatigue tests on SCS-6/Ti-15-3 were performed to investigate the fatigue life and residual strength behavior of TMCs with different fiber volume fractions. Results indicate that fiber volume fraction seems to have an effect on both of these quantities. Lower fiber percentages result in a material where the characteristics of the matrix, such as hardening or cracking, play a much larger role in the composite response. Fatigue lives were not affected by fiber volume fraction at higher strain ranges, but lower fiber volume fractions resulted in shorter fatigue lives at lower strain values. Also, a slight increase in residual strength occurred up to 75 pct of fatigue life, for the lower-fiber volume fraction material. Despite these distinctions between specimens with different fiber contents, all specimens tested retained the majority of their strength prior to failure.

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Mechanistically-based probabilistic methods for the prediction of fatigue damage

Cited by 8 publications

References 12 publications

On the Influence of Microstructure on the Fracture Behavior of Gamma-Based Titanium Aluminides. III. Effects of Interstitials and Microalloying with W

On the Influence of Microstructure on the Fracture Behavior of Gamma-Based Titanium Aluminides. III. Effects of Interstitials and Microalloying with W

Transverse behavior and acoustic-emission analysis of titanium metal-matrix composites under tensile loading

Degradation of residual strength in SCS-6/Ti-15-3 Due to fully reversed fatigue

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