en>Sanjib87: /* References */

2012-07-20T17:34:58Z

References

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{{Unreferenced|date=December 2009}}
'''Gauge factor''' (GF) or '''strain factor''' of a [[strain gauge]] is the ratio of relative change in [[electrical resistance]] to the [[strain (physics)|mechanical strain]] ε, which is the relative change in length.

::<math>GF = \frac{\frac{\Delta R}{R}}{\varepsilon} = \frac{\frac{\Delta\rho}{\rho}}{\varepsilon} + 1 + 2\nu </math>

In practice, the resistance is also dependent on [[temperature]]. The total effect is

::<math>\frac{\Delta R}{R} = GF \varepsilon + \alpha \theta</math>

Where
* ε = [[Deformation (mechanics)|strain]] = <math>\Delta L / Lo</math>
**<math>\Delta L</math> = absolute change in length
** <math>Lo</math> = original length
* ν = [[Poisson's ratio]]
* ρ = [[Resistivity]]
* ΔR = change in strain gauge resistance
* R = unstrained resistance of strain gauge
* α = [[temperature coefficient]]
* θ = temperature change

For many materials there is no change in resistivity (<math>\Delta\rho=0</math>), for these materials the gauge factor is simply

::<math>GF = 1 + 2\nu </math>

General examples of Gauge Factor values:

{| class="wikitable"
|-
! Material
! Gauge Factor
|-
| Metal foil strain gauge
| 2-5
|-
| Thin-film metal
| 2
|-
| Single crystal silicon
| -125 to + 200
|-
| Polysilicon
| ±30
|-
| Thick-film resistors
| 100
|}

{{DEFAULTSORT:Gauge Factor}}
[[Category:Equations]]

Superconductor Insulator Transition - Revision history

en>Sanjib87: /* References */