144
Z. Wang et al.
Table 13.2 Characteristic
parameters
Parameter type
Parameter name
Time domain index
Variance, RMS, peak-peak, peak
Square root amplitude, skewness
Kurtosis, absolute average
magnitude
Centroid amplitude
Dimensionless index
Peak index, pulse index, margin
index
Waveform index, kurtosis index
Frequency domain index Centroid frequency, mean square
frequency
RMS frequency, frequency domain
peak
Frequency domain variance
Frequency domain mean amplitude
Frequency domain peak frequency
0
200
400
600
800
1000
t / min
-1
0
1
2
3
4
Amplitude A / V
Variance
RMS
Mean Square Frequency
Frequency Domain Variance
RMS Frequency
Absolute Average Magnitude
Square Root Amplitude
Centroid amplitude
Peak-Peak
Peak
Frequency Domain Peak
Fig. 13.9 Statistical index group 1
13.3.4 Fatigue Evolution Law of Ball Bearing
To sum up, the ball bearing fatigue evolution law with acoustic emission is summarized as follows which is based on the trend analysis with the improved AE
Index.
The acoustic emission fatigue evolution of ball bearings can be divided into initial
operation stage, slight damage stage, pitting stage and spalling stage.
(1) On initial stage, most of the indexes amplitude are at a high level. This may
be due to the slight plastic deformation process at this stage. Usually, at the