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Full text release has been delayed at the author's request until May 06, 2024

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Impact of the Fully Reversed Loading Condition on Gear Tooth Bending Strength

Hong, Isaac J
http://rave.ohiolink.edu/etdc/view?acc_num=osu1546001449617063

Abstract Details

2019, Doctor of Philosophy, Ohio State University, Mechanical Engineering.
In this study, tooth bending fatigue lives of spur gears are studied both experimentally and theoretically. The primary focus is given to long-cycle fatigue performance of gears loaded under fully released conditions (e.g. a sun or ring gear in a planetary gear set) and under fully reversed conditions (e.g. planet gears in a planetary gear set). As no experimental data as well as no experimental set-up existed to quantify the differences in fatigue lives of a gear subjected to these two different loading conditions, the first main task of this investigation is to develop such an experimental methodology that enables such evaluations. For this, a new test gear geometry whose likely failure mode is tooth breakage under long-cycle fatigue conditions is designed and developed. Novel gear fatigue test machines that are capable of testing gear specimens under both fully reversed and fully released loading conditions are designed and fabricated. Vibration-based diagnostics systems are devised to facilitate immediate suspension of tests at the onset of tooth breakage. Dynamic behavior of the test machines are characterized to select operating test conditions that have the least amount of dynamic influences, and to quantify unavoidable dynamic root stress factors at these operating conditions. The experimental methodology developed here is employed to conduct long-cycle fatigue experiments to generate stress-life curves for both fully released and fully reversed loading conditions. These sets of data are analyzed statistically and compared to each other to establish a fully reversed to fully released stress ratio that would result in the same tooth bending fatigue life. This empirical ratio is implemented with kinematics of planetary gear sets to define ring-to-sun and planet-to-sun stress ratios as a function of desired gear set life such that each gear component has the same life expectancy. On the modeling side, multi-mesh deformable-body gear contact models of the test gears are developed under both loading conditions to predict stress tensor time histories along the root fillets. With available independently collected basic material data, measured residual stress profiles, and predicted stress time histories, representative multiaxial fatigue models are implemented to generate theoretical stress-life curves for both loading conditions. Comparisons of these predictions to measurements indicate that the models are reasonably accurate under fully reversed loading conditions while they overpredict fully released fatigue lives. At the end, recommendations are made towards further improvement of the theoretical and experimental methodologies presented in this work.
Ahmet Kahraman, Dr. (Advisor)
Amos Gilat, Dr. (Committee Member)
Randall Mathison, Dr. (Committee Member)
218 p.
Aerospace Engineering; Mechanical Engineering
gears; fatigue; gear tooth bending fatigue;

Recommended Citations

Citations

  • Hong, I. J. (2019). Impact of the Fully Reversed Loading Condition on Gear Tooth Bending Strength [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1546001449617063

    APA Style (7th edition)

  • Hong, Isaac. Impact of the Fully Reversed Loading Condition on Gear Tooth Bending Strength. 2019. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1546001449617063.

    MLA Style (8th edition)

  • Hong, Isaac. "Impact of the Fully Reversed Loading Condition on Gear Tooth Bending Strength." Doctoral dissertation, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1546001449617063

    Chicago Manual of Style (17th edition)

osu1546001449617063
© 2019, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.