Torque measurements on the face of a pulley 2

[soheyl81]

Hi All,

I need to measure the torque on a shaft. Since the shaft surface is not accessible, I want to measure the shear stresses using strain gauges on the face of the flywheel that is attached to one side of the shaft. How should I build a bridge for such measurement?

Thanks

 

[Jboggs]

If the component you're talking about is truly a flywheel, and not a pulley, it sees no torque. A flywheel doesn't transmit torque. It just stabilizes speed.

 

[pylfrm]

soheyl81,

A drawing of the shaft and flywheel would probably be helpful.

A flywheel doesn't transmit torque. It just stabilizes speed.

A flywheel stabilizes speed by applying torque when the speed changes. If it's not applying torque, it's not doing any good.

pylfrm

 

[GregLocock]

In my experience it is easy to overthink strain gauges. If you have a torque transmitting component then in the linear range the strain measured anywhere in any direction will be proportional to the torque being transmitted, so long as it is in the load path. Now, people who have specialised in strain gages will get all hoity toity about that and in some circumstances they are right.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[gruntguru]

Agree with Greg. Would add that gauge orientation should be reasonably aligned with a principle stress axis to get good sensitivity.

je suis charlie

 

[drawoh]

soheyl81,

Is the strain gauge attached to the thing that it rotating? How do you plan to get the wires off?

--
JHG

 

[Compositepro]

You can also measure torque by measuring the change in phase between timing marks on each end of the shaft.

 

[GregLocock]

drawoh - we used to use a little wireless transmitter, easy enough with Arduino these days. The problem is you need to have a system that is balanced otherwise you break stuff.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Strong]

H have an older model of this strain gage telemetry product that would work well for your application:

http://www.binsfeld.com/torquetrak/torquetrak-10k/

Walt

 

[FeX32]

We use wireless strain gauges all the time. (Honeywell)
One thing to note. Make sure there is sufficient strain in the location you are using the gauge. Most of the time you need to design the 'shaft' or 'pilley' to have this inherent... otherwise you are tying to measure something way into the noise component of the signal.