X90 mobile modules
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X90 mobile system User's manual V 1.20 - Translation of the original manual
Sensor positioning
In order to optimally measure and detect the sound propagation of damage, the position of the sensor must be
carefully selected. Although it is often not possible to mount a sensor at the absolute best position, this is not
always necessary. Since sound waves propagate throughout the entire structure, the damage frequencies can be
measured at various locations with varying intensity or amplitude (green arrow). If a flexible connection is used, a
valid measurement is no longer possible (red arrow).
Shaft
Elastic
coupling
Bearing A with
bearing damage
on the outer ring
Bearing B without
Motor
bearing damage
Figure 67: Suitable and unsuitable sensor attachments
5.4.1.6.2.2 Oscillations - Overview of measuring structure-borne sound
Oscillations
Oscillations are forms of movement that occur very frequently in nature. Harmonic oscillation is the third basic type
of form of movement alongside uniform movement and uniform accelerating movement. An oscillation or vibration
is a cyclic, i.e. repetitive simultaneous movement of a structure in its rest or equilibrium position.
Period duration T [s]
Amplitude
Time
Figure 68: Illustration of a basic oscillation
