Application of resistance strain gauge sensor
Resistance strain gauge sensors mainly have a variety of force sensors, pressure sensors, acceleration sensors and various strain gauges The application of resistance strain gauge sensors can be summarized in two aspects:
① Directly used to measure the strain or stress of the structure. For example, in order to study the stress and deformation of some components such as machinery, Bridges and buildings under working conditions, strain gauges of different shapes can be pasted on the predetermined parts of the components to measure the tensile and compressive stresses, torque and bending moments of the components, providing reliable experimental data for structural design, stress check or prediction of component failure.
The strain gauge is attached to the elastic element as a sensor for measuring physical parameters such as force, displacement, pressure and acceleration. In this case, a strain proportional to the measured strain is obtained through the elastic element, which is then converted by the strain gauge into a change in resistance. When using resistance strain gauge sensors, some problems should be noted, such as mechanical lag, zero drift, insulation resistance, etc. The reasons for these problems are often related to the bonding process of the strain gauge, such as the choice of binder, the protection of the strain gauge, the surface processing and cleaning of the elastomer. In addition, due to the temperature sensitivity of the electric anode, when the ambient temperature changes or the influence of its own working current, it will lead to inhibition of thawing due to temperature rise. Bring measurement error, in this case also need to carry out temperature compensation. The resistance strain gauge is a kind of convenient, adaptable and relatively complete device, which has a broad application prospect.
Types of strain gauge sensors
1. Strain gauge force sensor
The force sensor is a kind of sensor used in test technology and industrial measurement, among which the strain gauge force sensor is the most, and the sensor range is from 0.1 to 107N. The force sensor is mainly used as a force measuring element of various electronic scales and material testing machines, or for ground testing of aircraft and aeroengines, etc., according to the elastic component structure type (such as cylindrical cylinder, ring, beam, wheel width, etc.) and load properties (such as tension, pressure, bending and shear, etc.), it is divided into many types of strain gauge sensors using four same strain gauges. When the measured force changes, two of the strain gauges feel the tensile strain and the resistance increases, and the other two strain gauges feel the compressive strain and the resistance decreases. The resistance is converted into a change in voltage via a four-arm bridge. This results in maximum sensitivity with good linearity and temperature compensation.
2. Strain type pressure sensor
The pressure sensor is mainly used to measure the pressure of the fluid, depending on the structure of the elastomer has a single type and a combined type of the single type refers to the strain gauge directly attached to the pressure elastic diaphragm or cylinder. The structure, stress distribution and fabric of the diaphragm strain pressure sensor are similar to that of the solid state piezoresistive sensor.
The combined pressure sensor consists of a compression elastic element (diaphragm, capsule or bellows) and a strain elastic element (such as a beam). The former is subjected to pressure, and the latter is attached to a strain gauge. The advantage of this structure is that the pressure elastic element can isolate the effects of high temperature and corrosion on the fluid, so that the sensor has a good working environment.
3. Strain displacement sensor
The strain gauge displacement sensor converts the measured displacement into the deformation and strain of the elastic element, and then through the strain gauge strain bridge, the output power is proportional to the measured displacement. It can be used to measure static and dynamic displacement. Therefore, the stiffness of the elastic element is required to be small, the reaction force on the measured object is small, and the natural frequency of the system is required to be high and the dynamic frequency response characteristic is good. According to the different structural forms of elastic elements, strain displacement sensors can be divided into spring combined type, beam type, bow type and so on.
4. Other strain gauge sensors
In addition to the above main sensors, the strain gauge can also be used to form other strain sensors. For example, by means of elastic elements and strain gauges, strain type torque sensors can be formed. The key to the structure and design of the strain gauge sensor is the selection and calculation of the type of elastomer and the reasonable distribution and bridge of the strain gauge.
