Will our strain gauge accurately measure small forces on a baseball?

[CanoIsDbo]

Hi, my group and I are doing an experiment on forces experienced on a baseball. Our setup involves the baseball attached to a motor, which is coupled to a cantilever beam (1/2 inch thick, 7 inch long aluminum rod). The beam has a strain gauge attached to it and we are recording data with labView. Our concern is with the sensitivity of the strain gauge. We don't believe we are going to get any forces greater then 3.5 ounces on the beam. Will the strain gauge measure the very very small deflection from such small forces?

 

[Danger]

I would expect that the data sheet for the device should indicate the sensitivity. If it doesn't register what you want, could you go with a more flexible support arm?

 

[CanoIsDbo]

Yes, we were thinking of possibly going with a plexiglass arm or some other type of plastic. Our concern with that is the weight of the motor (2 pounds) causing the beam to bend.

 

[xxChrisxx]

Plastic is probably a bad idea. Metals give more reliable strain gauge readings, go for a thinner rod.

 

[FredGarvin]

It depends entirely on the gauge being used. You don't just grab one off the shelf and use it. A gauge is "sized" for the application.

 

[Danger]

Good point, Fred. I didn't think of that.

 

[CanoIsDbo]

So, any recommendations of what type of strain gauge I need, sensitivity wise?

Thanks

 

[xxChrisxx]

Depends on your expected deflection and how accurate you need to be. I'd ask a technician, or if you have someone how oversees and plans experiments ask them. Failing that you'll have to do some donkey work and read through strain gauge data sheets.

Its not something we can really answer properly because you'll defintely be able to get strain gauges that can read deflections in the 1/2 inch bar very accurately, they could be very expensive. Best bet is to look at what strain gauges are available to you, and design your experiement to fit them.

 

[Danger]

And when in doubt, ask the manufacturer. They should be more than happy to advise you as to what unit will best suit your needs.