ΔRα=Rt-R0=R0αΔt

Ambient temperature changes will not cause additional deformation

As the ambient temperature changes, the resistance wire will produce additional deformation, resulting in additional resistance changes.

length change

The resistance wire is stuck to the component

Relative change in total resistance of strain gauge

The performance parameters of the strain gauge itself (K0, α, βs) and the linear expansion coefficient βg of the tested piece

fully compensated

Use own temperature to select α, k0, βs

Composition of metal wires with different temperature coefficients

It consists of four bridge arms R1, R2, R3 and R4 and a bridge power supply U

When there is no change in the measured value, the four bridge arms meet a certain relationship and the output is zero; when the measured value changes, the balance of the measuring bridge is destroyed and there is a voltage output.

The ratio of the resistances of two adjacent arms should be equal, or the product of the resistances of two opposite arms should be equal.

When the relative change amount of bridge voltage U and resistance ΔR1/R1 is constant, the output voltage and sensitivity of the bridge are also constant and have nothing to do with the resistance value of each bridge arm resistor.

rL

Uo has a linear relationship with ΔR1/R1, there is no nonlinear error, and the bridge voltage sensitivity KU=E/2 is twice that of single-arm operation.

The bridge differential circuit not only has no nonlinear error, but its voltage sensitivity is 4 times that of monolithic operation.

When the strain gauge R1 is working, its resistance value changes very little, that is: △R1 is very small, and the corresponding output voltage of the bridge is also very small, that is, Uo is very small. Therefore, it is generally necessary to add an amplifier for amplification. The input impedance of the amplifier is much greater than the output impedance of the bridge. At this time, the bridge is still regarded as open circuit, and Uo is basically unchanged.