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Finite Element Method Based Analysis and Modeling in Rotordynamics

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2017, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
Rotordynamics refers to the analysis and study of the vibratory motion of rotating systems. The application of finite element analysis (FEA) to rotordynamics allows for modeling rotors that have complex geometry, which however requires sound understanding of basic concept and theory of rotordynamics and the constraints of existing FEA software. This study is to implement FEA based rotordynamics analysis to test, validate and compare capabilities of the rotordynamics part of commercial software, ANSYS and NASTRAN. The formation of FEA matrices containing concepts specific to rotordynamics such as gyroscopic effects, Coriolis force, spin softening effects, internal and external damping, and circulatory matrices are discussed focusing on their effects on the stability. A comparison between using the lumped parameter modeling approach and solid elements to model a rotor disk, and the benefits of the respective approaches are also discussed. The capabilities and limitations of current versions of ANSYS Workbench and NASTRAN are discussed with suggested improvements. While transient, harmonic, and modal analysis are all covered, the main focus is on modal analysis to specifically discuss some unique issues that rotordynamic modal analysis presents. Analyses show that the directivity information has to be used in the analysis for correct tracking of critical speeds and instability, which is a problem not encountered in non-rotating systems. The method to handle rotating structural damping in current commercial FEA software is discussed, and its implication is discussed using an analytical model of a simple system. For example, it is shown that modal solvers of current commercial software cannot properly handle frequency dependent structural damping.
Jay Kim, Ph.D. (Committee Chair)
Randall Allemang, Ph.D. (Committee Member)
David Thompson, Ph.D. (Committee Member)
79 p.

Recommended Citations

Citations

  • Weiler, B. (2017). Finite Element Method Based Analysis and Modeling in Rotordynamics [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1510917784717535

    APA Style (7th edition)

  • Weiler, Bradley. Finite Element Method Based Analysis and Modeling in Rotordynamics. 2017. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1510917784717535.

    MLA Style (8th edition)

  • Weiler, Bradley. "Finite Element Method Based Analysis and Modeling in Rotordynamics." Master's thesis, University of Cincinnati, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1510917784717535

    Chicago Manual of Style (17th edition)