Mechanical Influences - HBM CMD Serie Bedienungsanleitung

Tips for piezoelectric measurement technology
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The temperature effects can be minimized if you ensure
that
- the transducer is stored for sufficient time at the
application temperature,
- the transducer is not touched shortly before mea­
surement, as hand heat can warm up the trans­
ducer unevenly,
- a reset is implemented after every measurement
cycle.
Both drift and the disturbance variable of temperature are
particularly important in the case of long measurement
times and small forces - pay particular attention to the
instructions here.

14.5 Mechanical influences

In piezoelectric force sensors, the crystal lies in the direct
force flow. The measuring elements (quartz or gallium
phosphate) are designed for the maximum occurring nor­
mal force of each sensor. The initiation of bending
moments could cause transducer overload, as the crystal
is exposed to greater stress on one 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 (rated)
force in order to avoid an overload in such cases. The
following diagram shows the maximum permissible bend­
ing moment, dependent on the process force.
A2781-3.1 HBM: public
CMD