Resonant frequencies can be initiated by shock loading. A defect in a rolling-element bearing may excite the resonance in an inner or outer race, or in the ball/roller. Because of the interaction, a combination of resonant frequencies may be excited, thus causing 'ringing', which is a continuous vibration response of the bearing structure. Both races and rolling-elements can exhibit this 'ringing'. It is characterized by an exponentially decaying, high-frequency oscillation. The 'ring' will appear periodically at the 'pass' frequency corresponding to the faults that excite it. Resonant frequencies are structural characteristics. Their frequency does not depend on the speed of rotation of the bearing.
The frequency of free resonance of a rolling-element may be calculated by the following formula:7
| (1.11) |  |
The races will also exhibit resonant characteristics. Resonant frequencies for races can be calculated by the following relation [1.7]:
| (1.12) |  |
These resonant frequencies are in a free state and may alter when mounted on a structure.
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