Measurement of force value of tension machine the system is composed of force sensor, expander and data processing system. The most commonly used force sensor is strain gauge sensor.

The so-called strain gauge sensor is composed of strain gauge, elastic element and some accessories (compensation element, protective cover, wiring socket and loading part), which can change some mechanical quantity into electrical output. There are many kinds of strain gauge force sensors, including cylindrical force sensor, spoke type force sensor, s double hole type sensor and cross beam type sensor.

It is known from mechanics that the strain at a certain point of an elastic element under the premise of small deformation ε In direct proportion to the force exerted on the elastic element. Taking the S-type sensor as an example, when the sensor is subjected to the effect of the tensile force P, the strain of the elastic element is proportional to the change of the external force P because a strain gauge is pasted on the outer surface of the elastic element. Then, the strain gauge is connected to the measuring circuit to measure the output voltage and then the output force.

In brief, the external force P causes the deformation of the internal strain piece of the sensor, causes the imbalance of the bridge, and then causes the change of the output voltage of the sensor. We can know the magnitude of the force by measuring the change of the output voltage.