Damage Identification of Rotating Blades Based on Fuzzy C-Means and Frequency Response Function Curvature Methods

Table 1

Dimensional and nondimensional statistical features and their physical meanings.

Dimensional		Nondimensional
Expressions	Physical meaning	Expressions	Physical meaning
	Describe the stability of signals		Reflect the asymmetry of signal amplitude
Mean value		Skewness
	Describe the vibration energy of the signal		Reflect range of signal impact energy
Root mean square		Kurtosis
	Reflect the dynamic part in the change of amplitude		Reflect the trend of fault signal
Variance		Shape indicator
	Describe the extent to which data deviate from the mean		Describe the magnitude of signal impact energy
Standard deviation		Impulse indicator
	Describes the range of the change of signals		Describe the magnitude of signal impact energy
Peak-to-peak value		Crest indicator
	Describe the strength of the signal		Describe the magnitude change to reflect the wear condition
Peak value		Clearance indicator