42 Estimating Rotor Suspension Parameters from Runout Data 379 Fig. 42.9 Slow-roll–corrected runout in polar coordinates—trial run Fig. 42.10 Difference in slow-roll–corrected runout magnitude values The results show that the tested suspension has negative values of effective mass at low frequencies. The effective damping peaks near 1.8 times the second rigid-body mode natural frequency and then rapidly drops in magnitude, apparently approaching an asymptotic value near 0 at higher frequencies. The effective mass also appears to approach 0 at higher frequencies. Because actual suspension system stiffness values are unknown, there is no way to directly compare the estimated values of the tested suspension with known values. Some indication of the validity of the estimated suspension values can be obtained by comparing the calculated and measured second rigid-body critical speed and Q values of the tested rotor/suspension. Using the estimated suspension properties in the rotor dynamics model gives a ∼2% error in the frequency estimate and a ∼7% error in the Q-value estimate. This agreement between the measured and predicted critical speeds and Q values indicates, but does not confirm, that the method described in this report for estimating suspension parameters from runout data is valid.
RkJQdWJsaXNoZXIy MTMzNzEzMQ==