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Structural Engineering and Mechanics Volume 50, Number 1, April10 2014 , pages 019-036 DOI: https://doi.org/10.12989/sem.2014.50.1.019 |
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Krylov subspace-based model order reduction for Campbell diagram analysis of large-scale rotordynamic systems |
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Jeong Sam Han
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| Abstract | ||
| This paper focuses on a model order reduction (MOR) for large-scale rotordynamic systems by using finite element discretization. Typical rotor-bearing systems consist of a rotor, built-on parts, and a support system. These systems require careful consideration in their dynamic analysis modeling because they include unsymmetrical stiffness, localized nonproportional damping, and frequency-dependent gyroscopic effects. Because of this complex geometry, the finite element model under consideration may have a very large number of degrees of freedom. Thus, the repeated dynamic analyses used to investigate the critical speeds, stability, and unbalanced response are computationally very expensive to complete within a practical design cycle. In this study, we demonstrate that a Krylov subspace-based MOR via moment matching significantly speeds up the rotordynamic analyses needed to check the whirling frequencies and critical speeds of large rotor systems. This approach is very efficient, because it is possible to repeat the dynamic simulation with the help of a reduced system by changing the operating rotational speed, which can be preserved as a parameter in the process of model reduction. Two examples of rotordynamic systems show that the suggested MOR provides a significant reduction in computational cost for a Campbell diagram analysis, while maintaining accuracy comparable to that of the original systems. | ||
| Key Words | ||
| model order reduction; Krylov subspace; rotordynamics; Campbell diagram; damped eigenvalue analysis; whirling frequency; critical speed | ||
| Address | ||
| Jeong Sam Han : Department of Mechanical Design Engineering, Andong National University, Andong 760-749, Korea | ||