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Impact damping and friction in non-linear mechanical systems with combined rolling-sliding contact

Abstract Details

2014, Doctor of Philosophy, Ohio State University, Mechanical Engineering.
This research is motivated by the need to have a better understanding of the non-linear contact dynamics of systems with combined rolling-sliding contact such as cam-follower mechanism, gears and drum brakes. Such systems, in which the dominant elements involved in the sliding contact are rotating, have unique interaction among contact mechanics, siding friction and kinematics. Prior models used in the literature are highly simplified and do not use contact mechanics formulation hence the dynamics of the system are not well understood. The main objective of this research is to gain a fundamental understanding of the non-linearities and contact dynamics of such systems, for which a cam-follower mechanism is used as an example case. Specifically, the non-linearities, impact damping and coefficient of friction are analyzed in this study. The problem is examined using a combination of analytical, experimental, and numerical methods. First, the various non-linearities (kinematic, dry friction, and contact) of the cam-follower system with combined rolling-sliding contact are investigated using the Hertzian contact theory for both line and point contacts. Alternate impact damping formulations are assessed and the results are successfully compared with experimental results as available in the literature. The applicability of the coefficient of restitution model is also critically analyzed. Second, a new dynamic experiment is designed and instrumented to precisely acquire the impact events. A new time-domain based technique is adopted to accurately calculate the system response by minimizing the errors associated with numerical integration. The impact damping force is considered in a generalized form as a product of damping coefficient, indentation displacement raised to the power of damping index, and the time derivative of the indentation displacement. A new signal processing procedure is developed (in conjunction with a contact mechanics model) to estimate the impact damping parameters (damping coefficient and index) from the measurements by comparing (on the basis of three residues) them to the results from the contact mechanics model. Also few unresolved issues regarding the impact damping model are addressed using the experimental results. Third, the coefficient of friction under lubrication is estimated using the same experimental setup (operating under sliding conditions). A signal processing technique based on complex-valued Fourier amplitudes of the measured forces and acceleration is proposed to estimate the coefficient of friction. An empirical relationship for the coefficient of friction is suggested for different surface roughnesses based on a prior model under lubrication. Possible sources of errors in the estimation procedure are identified and quantified. Some of the major contributions of this research are as follows. First, impact damping model was determined experimentally and related unresolved issues were addressed. Second, coefficient of friction for a cam-follower system with point contact under lubricated condition was estimated. Finally, better understandings of the effect of non-linearities and shortcomings of coefficient of restitution formulation are obtained.
Rajendra Singh (Advisor)
Dennis Guenther (Committee Member)
Ahmet Kahraman (Committee Member)
Vishnu Baba Sundaresan (Committee Member)
Jason Dreyer (Committee Member)
179 p.

Recommended Citations

Citations

  • Sundar, S. (2014). Impact damping and friction in non-linear mechanical systems with combined rolling-sliding contact [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1386245045

    APA Style (7th edition)

  • Sundar, Sriram. Impact damping and friction in non-linear mechanical systems with combined rolling-sliding contact. 2014. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1386245045.

    MLA Style (8th edition)

  • Sundar, Sriram. "Impact damping and friction in non-linear mechanical systems with combined rolling-sliding contact." Doctoral dissertation, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1386245045

    Chicago Manual of Style (17th edition)