378 B. Damiano Fig. 42.7 Slow-roll–corrected runout in polar coordinates—reference run Fig. 42.8 Slow-roll–corrected runout magnitudes—trial run where M(ω) is the frequency-dependent effective mass, C(ω) is the frequency-dependent effective damping, and ωis the vibration frequency. A MATLAB function was written to perform the optimization used to estimate the suspension parameters. At each rotational speed, an ORNL–developed rotor dynamics code was used to calculate the runout for the applied trial weight, assuming effective mass and damping values. The error measure used in the optimization is simply the sum of the absolute values of the differences between the calculated and measured runouts. The MATLAB function fminsearch was used to adjust the effective mass and damping values to minimize the error measure, giving the best match between the measured and calculated runout. This process was repeated for each rotational speed, resulting in a frequency-dependent estimate of the right end suspension parameters. Figure 42.12 shows the estimated values of effective damping and effective mass for the tested suspension. These values were smoothed manually before being used in the rotor dynamic models.
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