The gauge factor of a strain gauge

[Jimbo bob]

Hi all,
What does it mean for a strain gauge to have a negative gauge factor and why is it useful?
Any help or ideas are much appreciated

 

[Arouse1973]

I think it must mean the resistance goes down with strain. I suspect different strain gauge materials are used for this?
Adam

 

[Jimbo bob]

I think it must mean the resistance goes down with strain. I suspect different strain gauge materials are used for this?
Adam

Oh, I see. That makes sense. But when I think about it I wonder why would someone want to use a negative gauge factor over a positive one?

 

[Gryd3]

Oh, I see. That makes sense. But when I think about it I wonder why would someone want to use a negative gauge factor over a positive one?

Depends on the configuration of your Wheatstone bridge for example.
Your previous topic showed two strain gauges of equal type on the bottom half of the bridge. This results in both sides of the bridge changing as the sensors react.
By using one positive and one negative, you could put both sensors on one side of the bridge or both! Imagine how sensitive you could make a bridge with 2 of each sensor. You would not use a resistor in the bridge.

 

[(*steve*)]

Wikipedia confirms @Arouse1973's answer.

This has some examples, but I didn't read far enough to find out whether this is inherently useful for anything.

 

[Jimbo bob]

Quite useful. Thank you all!