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Isothermal Fatigue Life Prediction Techniques

Wertz, John Nicholas
http://rave.ohiolink.edu/etdc/view?acc_num=osu1363195868

Abstract Details

2013, Doctor of Philosophy, Ohio State University, Aero/Astro Engineering.
Substantial progress has been made in advancing a pre-existing energy-based fatigue life prediction method into a powerful tool for real-world application through three distinct analyses, resulting in considerable improvements to the fidelity and capability of the existing model. First, a torsional fatigue life prediction method with consideration for the identification and incorporation of loading multiaxiality was developed and validated against experimental results from testing of Aluminum 6061-T6 specimens at room temperature. Second, a unique isothermal-mechanical fatigue life testing capability was constructed and utilized in the development of an isothermal-mechanical fatigue life prediction method. This method was validated against experimental data generated from testing of Aluminum 6061-T6 specimens at multiple operating temperatures. Third, alternative quasi-static and dynamic constitutive relationships were applied to the isothermal-mechanical fatigue life prediction method. The accuracy of each new relationship was verified against experimental data generated from testing of two material systems with dissimilar properties: Aluminum 6061-T6 at multiple operating temperatures and Titanium 6Al-4V at room temperature. Each investigation builds upon a previously-developed energy-based life prediction capability, which states: the total strain energy dissipated during both a quasi-static process and a dynamic process are equivalent and a fundamental property of the material. Through these three analyses, the energy-based life prediction framework has acquired the capability of assessing the fatigue life of structures subjected to unplanned multiaxial loading and elevated isothermal operating temperatures; furthermore, alternative constitutive relationships have been successfully employed in improving the fidelity of the life prediction models. This work represents considerable advancements of the energy-based method, and provides a firm foundation for the growth of the energy-based life prediction framework into the thermo-mechanical fatigue regime. This future work will utilize many of the models developed for isothermal-mechanical fatigue; additionally, the isothermal-mechanical testing capability will be readily modified to perform thermo-mechanical fatigue.
Mo-How Herman Shen, Ph.D. (Advisor)
Noriko Katsube, Ph.D. (Committee Member)
Jack McNamara, Ph.D. (Committee Member)
Datta Gaitonde, Ph.D. (Committee Member)
Tommy George, Ph.D. (Other)
Onome Scott-Emuakpor, Ph.D. (Other)
146 p.
Aerospace Engineering; Aerospace Materials
fatigue; fatigue lifing; life prediction; energy-based; isothermal

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Citations

  • Wertz, J. N. (2013). Isothermal Fatigue Life Prediction Techniques [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1363195868

    APA Style (7th edition)

  • Wertz, John. Isothermal Fatigue Life Prediction Techniques. 2013. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1363195868.

    MLA Style (8th edition)

  • Wertz, John. "Isothermal Fatigue Life Prediction Techniques." Doctoral dissertation, Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1363195868

    Chicago Manual of Style (17th edition)

osu1363195868
1,004
© 2013, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.