Mechanical Influences - HBM PACEline CMD600 Manuel D'emploi

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CMD600
11.5

Mechanical influences

In piezoelectric force sensors, the crystal lies in the direct force flow. The
measuring elements (quartz or GaPO ) are designed for each sensor at the
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maximum occurring normal force. Applied bending moments can lead to a
overload of the transducer as the crystal is more strongly loaded on one side
and, in contrast, the load is relieved on the other side.
The maximum mechanical stress is calculated from the addition of the
stresses caused by the bending moment in the crystal and the load stresses
of the axial forces to be measured.
The maximum permitted surface pressure must not be exceeded under any
circumstances.
As the output signal is not dependent on the nominal (rated) force of the
sensor in piezoelectric sensors, it is possible to select sensors with a higher
nominal force in order to avoid an overload in such cases. The following
diagram shows the maximum permissible bending moment, dependent on the
process force. The highest permissible bending moment can be accepted by
the force washer with 50% initial stress.
If the bending moment is generated by a force from the side, a lateral force is
also produced reducing the maximum values.
CFW: Permissible bending moment
Nominal force (kN)
A2781−2.1 en/de/fr