Rotordynamic instability : nonlinear modeling and analysis /
A basic rotordynamic model is developed for an crographics.
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| Format: | Thesis eBook |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Subjects: | |
| Online Access: | Link to OAK Trust copy |
| Summary: | A basic rotordynamic model is developed for an crographics. unbalanced rotor connected to a shaft modeled as a continuous beam. This model examines the effects of nonlinear dynamics strictly related to the rotor and shaft. The model dynamics include the effects of concomitant spin rate, finite rotor rotation, and a noncentrally located rotor. Equations of motion are derived using a work-energy description. The equations are developed in partial differential form using an Euler-Bernoulli constitutive model for shaft material. Equations of motion are also expressed in ordinary differential form using assumed modes and Lagrange's equation. A sensitivity analysis is presented for variations in rotor to shaft mass ratio, rotor location, imbalance magnitude, and mass moment of inertia. Simulations show the effects of perturbations about constant spin rates as well as constant torque inputs. Results of the sensitivity analysis show that increasing the mass ratio increases the magnitude of shaft deformation at the rotor while decreasing the first natural frequency. Additionally, moving the rotor away from midspan decreases shaft deformation at the rotor while increasing the value of the first natural frequency. A stability analysis is presented for perturbations about a constant spin rate, nonprecessing equilibrium point. The model stability is analyzed as a function of mass ratio, rotor location, imbalance magnitude, moment of inertia, and spin rate. The stability analysis shows that the spin rate at instability onset increases as the mass ratio is increased and decreases as the rotor is positioned away from midspan. Also, the spin rates at instability onset predicted by the stability analysis are found to be higher than values attained from constant spin rate simulations of the nonlinear equations of motion. Finally, frequency components of the constant spin rate simulations are compared to eigenvalues from the stability analysis. The frequencies of the eigenvalues are shown to closely match the frequency components of the constant spin rate simulations. |
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| Item Description: | Vita. "Major subject: Mechanical engineering". |
| Physical Description: | xi, 71 leaves : illustrations ; 28 cm. Also available online. |
| Bibliography: | Includes bibliographical references (leaves 60). |