Investigation on Free Vibration of Rotating Cylindrical Shells with Variable Thickness

Table 4

Comparisons of natural frequencies for the RCS.

Modes	fb			ff
	FEM [28]	Present	Error (%)	FEM [22]	Present	Error (%)
(1, 3)	1830.45	1831.08	0.03	1436.24	1437.09	0.06
(1, 4)	1714.57	1713.40	0.07	1396.32	1395.50	0.06

Note. and represent the backward wave frequency and forward wave frequency, respectively.