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Effects of Mission Overloads on Fatigue Crack Growth in Ti-6Al-2Sn-4Zr-2Mo

Solomon, Daniel Maurice
http://orcid.org/0000-0003-1361-2463
http://rave.ohiolink.edu/etdc/view?acc_num=dayton1532083676103601

Abstract Details

2018, Master of Science (M.S.), University of Dayton, Materials Engineering.
Aircraft turbine engines, especially military engines, experience variable amplitude loading (mission loading) during operation. Predicting the impact of overloads in turbine engines is key in interpreting fatigue damage and assessing the reliable lifetime of components. The objective of this study was to understand the effects of single and repeated overloads during fatigue crack growth in Ti-6Al-2Sn-4Zr-2Mo used in aircraft turbine engine rotor components. Experiments were conducted using compact tension specimens in a servo-hydraulic testing machine to measure the fatigue crack growth rates during the application of single overloads under stress intensity factor and load control. Additional experiments were conducted having, variable amplitude loading consisting of a controlled number of constant amplitude baseline cycles between periodic overloads. Single overload experiments revealed crack growth acceleration and not the classic retardation typically expected. Repeated overloads experiments demonstrated that Miner’s rule accurately predicted realistic overload behavior. Overall, the crack growth rates during single overload or repeated overloads resulted in consistent behavior, and significant crack growth retardation was not observed throughout testing in this material. In addition, crack growth rates were similar for overload and underload block fatigue conditions. The understanding of this behavior and the impact on aircraft turbine engine life tracking using Total Accumulated Cycles (TACs) was discussed. It appeared that minor cycles were generally more damaging than currently accounted for in military turbine engine life tracking.
Charles Browning (Committee Member)
110 p.
Aerospace Materials; Engineering; Materials Science
Fatigue Crack Growth; Variable Amplitude Loading; Mission Loading; Ti-6242; Compact Tension

Recommended Citations

Citations

  • Solomon, D. M. (2018). Effects of Mission Overloads on Fatigue Crack Growth in Ti-6Al-2Sn-4Zr-2Mo [Master's thesis, University of Dayton]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1532083676103601

    APA Style (7th edition)

  • Solomon, Daniel. Effects of Mission Overloads on Fatigue Crack Growth in Ti-6Al-2Sn-4Zr-2Mo. 2018. University of Dayton, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=dayton1532083676103601.

    MLA Style (8th edition)

  • Solomon, Daniel. "Effects of Mission Overloads on Fatigue Crack Growth in Ti-6Al-2Sn-4Zr-2Mo." Master's thesis, University of Dayton, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1532083676103601

    Chicago Manual of Style (17th edition)

dayton1532083676103601
432
© 2018, all rights reserved.
This open access ETD is published by University of Dayton and OhioLINK.