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Impact of system-level factors on planetary gear set behavior

Ligata, Haris
http://rave.ohiolink.edu/etdc/view?acc_num=osu1172599656

Abstract Details

2007, Doctor of Philosophy, Ohio State University, Mechanical Engineering.
Planetary gear sets are widely used in many diverse automotive, aerospace and industrial drive train applications. Several unique system-level influences must be incorporated in the design of planetary gear sets. In this dissertation, the impact of the several important system-level factors on gear stresses and gear bending fatigue lives are investigated both experimentally and theoretically. First, results of an experimental study are presented to describe the impact of certain types of manufacturing errors on gear stresses and the individual planet loads of an n-planet planetary gear set (n=3 to 6). The experimental set-up includes a specialized test apparatus to operate a planetary gear set under typical speed and load conditions and gear sets having tightly controlled intentional manufacturing errors. A method for computing the planet load sharing factors from root strain time histories is proposed. The results clearly indicate that manufacturing errors influence gear stresses and planet load sharing significantly. Gear sets having larger number of planets are more sensitive to manufacturing errors in terms of planet load sharing behavior. A finite element based computational model and a discrete planet load-sharing model are also developed and validated. A set of closed-form planet load sharing formulae is derived assuming all planets carry a certain amount of load and they are equally spaced. A statistical analysis that uses these planet load-sharing formulae is also presented to predict the distribution of planet loads, given statistical distributions of manufacturing errors. Secondly, the impact of gear body deflections and gear spline conditions on gear strains are investigated using the same computational models and the experimental set up by considering the ring gear rim thickness as a variable. The results indicate that gear stresses are impacted by gear deflections and spline conditions significantly. At the end, a stress-life based gear tooth bending fatigue model, combined with a generalized power flow formulation and a duty cycle discretization scheme is proposed. It is used to predict bending fatigue lives of the multi-stage planetary gears of an actual automatic transmission operating under a complex duty cycle.
Ahmet Kahraman (Advisor)
339 p.
planetary gear set; planetary gear design; gear life; planetary gear kinematics

Recommended Citations

Citations

  • Ligata, H. (2007). Impact of system-level factors on planetary gear set behavior [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1172599656

    APA Style (7th edition)

  • Ligata, Haris. Impact of system-level factors on planetary gear set behavior. 2007. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1172599656.

    MLA Style (8th edition)

  • Ligata, Haris. "Impact of system-level factors on planetary gear set behavior." Doctoral dissertation, Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1172599656

    Chicago Manual of Style (17th edition)

osu1172599656
4,754
© 2007, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.