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PS fork equipped with 8 semiconductor (4 by arm) strain gauges
G1
G2
G3
G4
G5
G6
G7
G8
10
50
77
10
50
77
26 26
Gauges location
Gauges G4 and G8 are bonded in the fork shaftGauges G2, G3, G6 and G7 are bonded in the wings of the arms of the forkGauges G1 and G5 are bonded in the flexible flat parts of the fork
Gauges location
Gauges G4 and G8 are mainly sensitive to the twist of the shaft in X axisGauges G2, G3, G6 and G7 are mainly sensitive to the deflections in Z directionGauges G1 and G5 are mainly sensitive to the deflections in X direction
G1
G2
G3
G4
G5
G6
G7
G8
10
50
77
10
50
77
26 26
X
Y
Z
Gauges location
G4
G2
G3
G1
Gauges location in the right arm of the fork. Gauges located in the left arm are symmetric to these gages as follow:
G1 and G5G2 and G6G3 and G7G4 and G8
Gauges location
IN
OUT
OUTPOSITION
IN POSITION
The strain gauges G2, G3,G6 and G7 are located in thisside of the fork
IN movement produces compression (resistance decrease) in gauges G2, G3, G6 and G7.OUT movement produces extension (resistance increase) in gauges G2, G3, G6 and G7.
The following setup has been built in order to calibrate the strain gauges installed on the fork. The goal of the calibration processis to collect the suitable data about the behaviour of the system to reproduce the deformations on the fork during the scan by mean ofthe variation of resistance measured in the strain gauges.
2
3
5
4
A progressively increasedknown load is applied in this pointof the arm and the deflections in thefork are measured by means of4 dial indicators
Gauges calibration - Deflection measurements
Shows the setup for gauges calibration in the right are of the fork, an equivalentsetup has been used in the left arm of thefork.
2
3
4
5
Gauges calibration - Deflection measurements
A lever fixed to the fork axisprovides information about the twist ofthe fork shaft.
Gauges calibration - Deflection measurements
d1
d2
d9
50
d3
d6
d7
d8
d10
d4
d5
30
35
48
Gauges calibration - Deflection measurements
Gauges calibration - Deflection measurements
Typical gauge calibration plot
Gauges calibration - Deflection measurements
Typical gauge calibration plot
Tension variation the right arm gauges IN movement
Results
Tension variation the right arm gauges OUT movement
Results
Displacement in point d1 based in the variation of resistanceof G1, IN movement.
Displacement in point d2 based in the variation of resistanceof G3, IN movement.
Results
Displacement in point d1 based in the variation of resistanceof G1, OUT movement.
Displacement in point d2 based in the variation of resistanceof G3, OUT movement.
Results
Deflection measurements
Deflection measurements
Next
• Perform measurement in the 2nd arm• Perform measurement in both arms at the same time with and without wire• Find correlation between displacements in the arms and the pattern of movement• Perform measurements in vacuum on both arm and wire resistance• Perform measurements using a more rigid fork• Introduce measure data in an analytical model of the wire to find a correlation
between wire resistance• variation and wire elongation due to vibrations• Compare different motion patterns
