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Investigation of asymmetric cubic nonlinearity using broadband excitation

Chawla, Rohan D
http://orcid.org/0000-0001-8415-7336
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553614075747602

Abstract Details

2019, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
Traditionally, electrodynamic shakers have been used to test nonlinear systems using sinusoidal excitation. However random excitation is desirable due to its lower testing times. In both cases, shakers affect system dynamics when used to test relatively light structures by introducing additional impedance. On the other hand, pneumatic excitation, a new technique developed at UC-SDRL [1] used for linear system identification, is used here to test nonlinear systems. This thesis focuses on testing a rig with a flexible beam with a known cubic nonlinearity using both a traditional electrodynamic shaker as well as the pneumatic excitation method. The results of these two methods are compared with each other. The property of nonlinear systems showing the presence of uncorrelated response at harmonics of the natural frequency is used in this thesis to investigate asymmetry in the system. Bilinearity present in the system due to asymmetry which was hard to detect from shaker test was clearly evident in pneumatic excitation test. The dips in the coherence function present due to harmonics of nonlinear response is differentiated from leakage errors using a nonlinearity detection algorithm developed at UC-SDRL. The presence of bilinearity is further con firmed by static loading tests in both directions as well as dynamic testing in the loaded con guration. The conclusions of the comparative study are presented and advantages of using pneumatic excitation over traditional shaker excitation are stated in the end.
Randall Allemang, Ph.D. (Committee Chair)
Allyn Phillips, Ph.D. (Committee Member)
David Thompson, Ph.D. (Committee Member)
75 p.
Mechanical Engineering
Structural Vibrations; Nonlinear Systems; Shakers Excitation; Pneumatic Excitation; Broadband Excitation

Recommended Citations

Citations

  • Chawla, R. D. (2019). Investigation of asymmetric cubic nonlinearity using broadband excitation [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553614075747602

    APA Style (7th edition)

  • Chawla, Rohan. Investigation of asymmetric cubic nonlinearity using broadband excitation. 2019. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553614075747602.

    MLA Style (8th edition)

  • Chawla, Rohan. "Investigation of asymmetric cubic nonlinearity using broadband excitation." Master's thesis, University of Cincinnati, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1553614075747602

    Chicago Manual of Style (17th edition)

ucin1553614075747602
176
© 2019, some rights reserved.Creative Commons License Investigation of asymmetric cubic nonlinearity using broadband excitation by Rohan D Chawla is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.