# Force sensor (small force over a great force)

J

#### Jack

Hi,

I would like to measure a force, in one direction (for exemple the tension in a cable or the force transmitted by steel piece). The measured force is approximately 1500 Newtons. This is a constant force.

There is also a dynamic force of amplitude 40 N.

I would like to be able to measure this dynamic force accurately. For example if the constant force is 1505N, the dynamic force would be 5N.

The problem is that this is in general too small to measure because this 5N can be confused with the noise of the sensor...

Is there a way to do this ? (if we forget about the 1 billion dollars sensor )

Thank you very much,
Jack

C

#### Curt Wuollet

Why not use a 100 N load cell in parallel with say, a 1500 N dead weight. You would need to mechanically limit the deflection on the load cell in case the force changed more than 100 N but that should give you what you need. Let me know if that isn't clear.

Regards
cww

J

#### Jack

Hi !

In fact I don't understand the dead weight in parallel. In fact, i'm not sure how this will decouple the static and dynamic force. Is it something like a 100N load cell, in parallel with a device that always take 1500N of the weight?

Thank you again!

Jack

J

#### Jack

Hi again,

To add more details, the 1500N static force can change but I would know this force. Would it be a good idea fo use a piezo force sensor to measure the dynamic force in series or parallel with a load cell ?

Jack

C

#### Curt Wuollet

Yes. thats the idea. Let's simplify and say you have the end of a cable and you attach a 100N load cell to a fixed object. This would put the whole 1505N on that cell. If you also attached another cable to the cable end and ran it over a pulley and hung a 1500N weight on it, it would take up 1500N of the cable tension leaving the load cell seeing 5N. It would see whatever the cable tension was minus the 1500N. You would want to mechanically limit the small load cell in case the cable broke or whatever.

Regards
cww