Load cells under vibration 1

[MechP]

Hello everyone,

I'm searching for a type of load cell with quick response and accurate output for an aerodynamic balance. I don't have much experience with load cells and I need to measure forces like lift and drag in a wind tunnel, but I'm concerned about vibrational effects and random variations in these forces due to turbulence and I want to make sure I get the most appropriate kind of cell for this job.
I appreciate any suggestions.
thanks

 

[MintJulep]

How quick is quick? How accurate is accurate?

What are the magnitude of the forces you are interested in, and how large are the perturbations?

But mostly the things you appear to be interested in are more functions of the signal processing and recording equipment used than of the load cell itself.

 

[MechP]

Thanks for your reply MintJulep,

The magnitude of the forces are relatively small, around 150 lbf for one cell and 30 lbf for another. I can't really quantify the perturbations or vibrations yet, but the amplitude should fall around +/- 5% of the force, and the frequency should be near 10 Hz.
I guess all I need to know right now is which kind of cell can do a better job with the output signal. And you're right about signal processing, but first I need to choose a sensor that can deliver a fast response that allows me to record the vibration.

 

[handleman]

Load cells themselves have no electronics or anything. A load cell is just a strain gauge assembled to a precisely-sized beam inside a neat package. I daresay that any load cell will give you the response time you need. 10Hz is really pretty slow. Granted, I don't have so intimate knowledge of load cells, but based on what I do know I wouldn't even start to be concerned with response time until you get in the kHz range. As Mint mentioned, the kicker will be what you use to analyze/process/record the signal.

-handleman, CSWP (The new, easy test)

 

[MechP]

Ok, thanks a lot handleman!

 

[rb1957]

i'd've thought the spec for the loadcell would define this.

note, your concern with noise on the load can be one of either ...

1) you don't want to see the noise, ie filter the loadcell output (a bypass filter ?)

or 2) you want to see it, you want the output to accurately track the input. a different solution ... a loadcell response at least twice the input frequency.

so if you have a quick acting loadcell you can see the input variations or not. talk to loadcell suppliers in your area ... load range and response vary with price ... you'll get what you pay for !

Quando Omni Flunkus Moritati

 

[zekeman]

For 10Hz input , the cheapest load cell coupled with a simple low pass filter will capture everything you need.

 

[MechP]

ok, thank you all for your advice,