Session: 27-02: Damping, Stability, Swirl-Induced Effects & Seal Dynamics.

Submission Number: 179166

Damping Models for Rotordynamic Transient Analysis 

Among the various ingredients of structural dynamics simulation, damping remains one of the least understood topics. The main reason is that unlike the stiffness and inertia forces, the damping forces cannot always be obtained from ‘first principles’ [1]. A fan blade out (FBO) analysis for an aircraft engine is usually performed in time-domain due to the presence of geometric nonlinearities and contact between stator-casing and the rotor. Different types of damping strategies are currently being employed by engine and airplane manufacturers in their FBO analysis. The most commonly used approaches for damping in the nonlinear transient analysis are:

a)       Rayleigh damping [2]

b)       Hybrid Modal Damping [3]

c)       Structural (Hysteretic) Damping [4]

-            Using equivalent viscous damping [5]

-            Enhanced Structural damping [6]

In transient analysis, often times it is not easy to see damping variation as a function of frequency or rotor speed. It is easier to see the effect of damping in complex eigenvalue analysis and frequency response analysis. In this paper, we will look at the behavior of different damping strategies described above in complex eigenvalue analysis, frequency response analysis and nonlinear transient analyses. This study will help the engineers to identify appropriate damping strategy to use in transient analysis depending on the underlying physics of the damping.

References

1.       Adhikari, Sondipon. Structural dynamic analysis with generalized damping models: analysis. John Wiley & Sons, 2013.

2.       Alipour, A., and F. Zareian. "Study rayleigh damping in structures; uncertainties and treatments." the 14th world conference on earthquake engineering. 2008.

3.       MSC NASTRAN. "Rotordynamics Users Guide." MSC Software Corporation (2024).

4.       Genta, Giancarlo, and Nicola Amati. "Hysteretic damping in rotordynamics: An equivalent formulation." Journal of Sound and Vibration 329.22 (2010): 4772-4784.

5.       D’Alessandro, Francesco, et al. "Damping Phenomena in Rotating Machines: A Focus on Rotor Damping With Synchronous and Asynchronous Excitation." Turbo Expo: Power for Land, Sea, and Air. Vol. 88032. American Society of Mechanical Engineers, 2024.

6.       Vaquer Araujo, Xavier, et al. "Validation of equivalent viscous damping methodologies." CEAS Space Journal 4.1 (2013): 31-39.

Presenting Author: Devesh Kumar Boeing

Presenting Author Biography: Applied Mathematician at Boeing

Authors:

Devesh Kumar Boeing
Don Powell Boeing