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Saleh2015 _Submitted_ Dissertation.pdf (4.2 MB)

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Assessment of Nonlinear Damping Elements for Vibro-Impacts in Automotive Torsional Systems with Discontinuous Nonlinearities

Saleh, Almahdi
http://rave.ohiolink.edu/etdc/view?acc_num=osu1449148151

Abstract Details

2015, Doctor of Philosophy, Ohio State University, Mechanical Engineering.
The topic of this dissertation is driven by a demand for more accurate drivetrain torsional system models in the ground vehicle industry as they may be used to troubleshoot transient dynamic, noise and vibration problems. Such driveline systems contain many discontinuous nonlinear elements whose elastic properties have been extensively studied in the literature. However, damping mechanisms involved during the transient events are yet to be adequately defined and quantified. This forms the chief goal of this research and thus two recent step response type, non-rotating laboratory experiments (as published) are re-examined and analyzed using multi-degree of freedom nonlinear system models. In particular, four dominant damping elements associated with vibro-impact phenomena in a typical vehicle drivetrain system are investigated: contact damping and hysteresis associated with gear mesh stiffness, oil squeeze damping in the gear mesh clearance, friction in the tapered rolling element bearings, and dissipative elements in a multi-staged clutch damper. First, the gear mesh dissipation contribution is associated with the loads carried by gear teeth in the presence of gear backlash. Dynamic hysteresis is investigated using a combined Hertzian contact stiffness expression (for the point contact) along with alternate impact damping formulations based on dry contacts. Further, the squeeze damping phenomenon is successfully formulated using the Reynolds equation. A lubricated contact damping expression is developed to calculate the minimum film thickness calculation during the contact loss between gears. The nonlinear dynamic system models with new gear mesh dissipation values, from both dry contact hysteresis and oil squeeze damping, match experimental results reasonably well. Next, friction torques in tapered bearings, which are geometrically coupled with the hypoid gear mesh force, are modeled by using a smoothened Coulomb friction model. It is found that inclusion of bearing friction in the driveline model has a significant influence on the number of impacts as well as on the shape of impulsive contact forces. Finally, damping mechanisms of a multi-staged clutch damper subsystem are identified (during the transient events due to a rapid variation in mean load) using signal processing and experimental methods. Formulas are developed to calculate both dry friction and viscous damping parameters directly from transient acceleration measurements using the wavelet transform, without a need to perform any integration process. Major contributions of this research are as follows. First, gear mesh damping mechanisms during the impact process due to material and lubricant squeeze between gear teeth are identified, modeled and validated. Second, dynamic interactions between bearing friction torques and gear mesh forces are investigated. Third, refined damping models suitable for impulsive type loading in multi-staged clutch dampers are proposed and justified. Also, a novel method that extracts nonlinear hysteretic and viscous damping from transient acceleration measurements is proposed and validated.
Rajendra Singh, Prof (Advisor)
Donald Houser, Prof (Committee Member)
Brian Harper, Prof (Committee Member)
Jason Dreyer, Prof (Committee Member)
132 p.
Engineering; Mechanical Engineering; Mechanics
vibro-impact; impact damping; transient dynamics; driveline clunk

Recommended Citations

Citations

  • Saleh, A. (2015). Assessment of Nonlinear Damping Elements for Vibro-Impacts in Automotive Torsional Systems with Discontinuous Nonlinearities [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449148151

    APA Style (7th edition)

  • Saleh, Almahdi. Assessment of Nonlinear Damping Elements for Vibro-Impacts in Automotive Torsional Systems with Discontinuous Nonlinearities . 2015. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1449148151.

    MLA Style (8th edition)

  • Saleh, Almahdi. "Assessment of Nonlinear Damping Elements for Vibro-Impacts in Automotive Torsional Systems with Discontinuous Nonlinearities ." Doctoral dissertation, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1449148151

    Chicago Manual of Style (17th edition)

osu1449148151
529
© 2015, some rights reserved.Creative Commons License Assessment of Nonlinear Damping Elements for Vibro-Impacts in Automotive Torsional Systems with Discontinuous Nonlinearities by Almahdi Saleh is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by The Ohio State University and OhioLINK.