Colleague and I have created system for torsional vibration measurement and have recorded this data (electrical motor is just started on 2 sec and turned off on aprox 12 sec). Could this data on this graph true? Anyone with experience in torsional vibration measurement please give me some hint.
AC motor flexibly coupled with shaft with rotor. Strain gauges are positioned next to the left bearing (shown on image).
Yes, but what is the unit used on the y axis of the graph? Maybe you do not know?
Oh, that. We have used strain gauges to measure deformation in 45 degrees direction (1/4 of the bridge was used = one strain gauge + 3 constant resistors). It is the output voltage of the wheatstone bridge (mV or uV, not sure). IT should be recalculated to obtain deformation.
Hi
I am guessing that you show strain n the Y-axis.
Perhaps you want to show RPM or RPS on the X-axis? To do so, you need to add also a rpm counter. You can do even more if you add a reference trigger on the shaft.
If you want to check your torsion sensor, try and measure the motor current - it should show the same trend as the torsion sensor.
Feel free to take a look also here
https://qringtech.com/2017/05/20/torsion-vibration-measurement-and-analysis-of-flue-gas-fan/
http://hpmemoryproject.org/an/pdf/an_243-1.pdf
Sincerely
Claes
Claes Richard Fredö , thank you for you answer, I would try current measurement on motor. You are right, strain is shown on Y axis and time on x axis.
If you use, eg a Rogowski coil on one phase, then you get also the motor rpm with a little bit of analysis.
Assuming you have a three phase motor, if you settle for indication of torsion vibration, then one can measure summed current, ie L1+L2+L3+Gnd. It is very easy. You will see torsion as soon as it truly loads the motor.
Ground current is also a good indicator.
have fun
Claes
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