Measurement modes 189
imc CANSAS Users Manual - Doc. Version 1.9 - 05.12.2014© 2014 imc Meßsysteme GmbH
Unit
When the strain is determined, the readings appear with the unit µm/m. For the mechanical stress one
can toggle between MPa and N/mm
2
. 1 GPa = 10
3
N/ mm
2
Note that the elastic modulus is always in GPa.
5.1.2.2 Bridge balancing
A significant characteristic of bridge measurements is the fact that the actual measurement signal is
attended by an offset which can be multiples of the input range. Measurement bridges, consisting for
instance of wire strain gauges (WSGs), respond to minuscule changes in their components' resistance (in
the mV/V = ppm = parts-per-million = 1E-6 range). The static initial asymmetry (offset) due to production
tolerances or assemble conditions of the components, by comparison, can be in the range of mV/V, in
other words in the range of the total input range or even multiples of it.
Since the offset also depends on the sensor connected it can't be calibrated for the device but must be
balanced “online”, before starting the measurement. The precondition for this is that the sensor used
must be set up in the system the same way for the balancing as for the measurement and may not be
stimulated dynamically.
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