Measurement of Force, Torque,
and Other Mechanical Variables With Strain
Gages
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Page 8 of 46
Building a D-I-Y Transducer
The first step in achieving a suitable D-I-Y
transducer is to arrive at the spring element material
and design. With respect to the material, there are
many alloys which would suffice for a moderately
accurate transducer, but the performance of the
transducer can be improved by the exercise of some
judgement in material selection. It is important, of
course, that the material have highly linear
stress/strain characteristics. Other desirable material
properties are low hysteresis and minimal creep under
sustained load. Machinability of the alloy is also a
factor, particularly if the spring element
configuration is at all complex. Among the steel
alloys, 4140, 4340, and 17-4 PH stainless steel are
good candidates, and are widely used by commercial
transducer manufacturers since they can be machined in
the unhardened condition and then heat treated to
develop the desired properties. Although not ordinarily
thought of as spring materials, aluminum alloys such as
2024-T8 are also suitable, and often selected for
low-capacity transducers.
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