| These animations
graphically illustrate the previous example. The displacement in each is
the same but the bearing on the right is completing 7 cycles for each cycle
completed by the bearing on the left. |
| But what we are really interested
in, of course, is the effect of the vibration on the bearing's life and
the machine's health. Again, knowing nothing about vibration analysis and
using only your common sense and knowledge of machines, which bearing will
fail in a shorter period of time ? It doesn't take a vibration 'expert'
to recognize that it will be the bearing on the right. But since the displacement
(a measure of stress) is constant, the determining factor must be something
else. |
It is actually two failure modes
that are increasing in likelihood with the frequency:
-
The fatiguing effect on the bearing
components.
-
The forces being applied to make the
bearing move.
|
| But since
the units are all related, why don't we just use a single amplitude unit
and simplify things ? |
