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Experimental
Several samples are provided for tensile test measurements in the Instron.
A special fixture permits spokes to be mounted in the tension testing grips
of the machine. Before mounting any sample,
determine its cross-sectional
area and length so that the force and displacement data collected by the
Instron can be converted into stress-strain information.
Adjust the position
of the Instron grips so that the piston that moves the lower grip is
at its zero position and the cross-head holding the load cell and upper grip
is high enough to permit the sample to be held firmly in both grips. Set the
safety limits on the Instron and use the computer to collect stress-strain data
under either position control (constant strain rate) or load control (constant
load ramp). Make sure that the data for each run are saved to an Excel spread
sheet that will permit conversion to stress and strain and plotting of
the full stress strain curve.
Compression data will be acquired using
different grips. Test samples in the form of spoke sections and tubes will be
used. Tests will be made under constant strain-rate and constant stress-ramp
conditions. Again, collect data in an Excel spreadsheet for later plotting
and manipulation. |
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