Title Fault Diagnosis Method of Gearbox Multifeature Fusion Based on Quadratic Filter and QPSO-KELM

Figure 7

The spectrum of fault signal before and after filtering: (a) inner race fault-without filter; (b) inner race fault-stable filter; (c) tooth break-without filter; (d) tooth break-stable filter.

(a)

(b)

(c)

(d)