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Gauge factor (GF) or strain factor of a strain gauge is the ratio of relative change in electrical resistance R, to the mechanical strain ε. The gauge factor is defined as: :: Where * ε = strain = * * = absolute change in length * * = original length * ν = Poisson's ratio * ρ = Resistivity * ΔR = change in strain gauge resistance * R = unstrained resistance of strain gauge ==Piezoresistive Effect== It is a common misconception that the change in resistance of a strain gauge is based solely, or most heavily, on the geometric terms. This is true for some materials (), and the gauge factor is simply: :: However, most commercial strain gauges utilise resistors made from materials that demonstrate a strong piezoresistive effect. The resistivity of these materials changes with strain, accounting for the first term of the defining equation above. In constantan strain gauges (the most commercially popular), the effect accounts for 20% of the gauge factor, but in silicon gauges, the contribution of the piezoresistive term is much larger than the geometric terms. This can be seen in the general examples of strain gauges below: 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gauge factor」の詳細全文を読む スポンサード リンク
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