Dynamics of Flexible Rotor Systems with an Interim Mass Unbalanced Disk Using a Spectral Element Model

Table 1

Natural frequencies (Hz) of the rotor system (𝑚_𝑈 = 0 kg, Ω = 100 Hz).

Modes	SEM(3)	FEM(𝑛)
		𝑛=3	𝑛=11	𝑛=21	𝑛=41	𝑛=51	𝑛=61
1st
Backward	158.806	158.901	158.807	158.806	158.806	158.806	158.806
Forward	160.245	160.336	160.246	160.245	160.245	160.245	160.245
2nd
Backward	858.810	916.713	859.182	858.891	858.827	858.819	858.810
Forward	891.508	956.441	891.933	891.601	891.528	891.519	891.508
3rd
Backward	1762.83	2390.46	1765.90	1763.51	1762.98	1762.91	1762.83
Forward	1781.60	2416.47	1784.75	1782.30	1781.75	1781.68	1781.60
4th
Backward	2913.20	3581.68	2924.14	2915.61	2913.71	2913.48	2913.20
Forward	3002.85	3676.30	3014.91	3005.51	3003.42	3003.17	3002.85

Note: (𝑛): the total number of finite elements used in the analysis.