Experimental Study on the Influence on Vibration Characteristics of Thin Cylindrical Shell with Hard Coating under Cantilever Boundary Condition

Table 4

The disadvantages of different vibration excitation devices for vibration test of TCS with or without hard coating.

Excitation device	Vibration parameters of TCS				Disadvantage
	Natural frequency	Modal shape	Damping ratio	Vibration response
Hammer	√	√	×	×	Pulse excitation level cannot be precisely controlled and the excitation force varies for each measurement, and double hit often leads to test errors in damping and vibration response measurement.
Electromagnetic exciter	×	×	×	×	The related force sensor will bring added mass and stiffness to TCS, which will severely affect test results of damping, natural frequency, and so forth.
Piezoelectric ceramic exciter	√	√	×	×	The excitation energy of piezoelectric ceramic exciter is often insufficient for TCS, which will result in poor response signal with low level of signal noise ratio.
Vibration shaker	√	√	√	√	Excitation frequencies are not that high, often limited to 1 Hz~3000 Hz, and the test procedures are often complicated.