Strain Gauge Technical Specifications

Release time:2021-12-14 03:31

1. Sensitive grid resistance

The resistance between the two soldering pads is what we called “Sensitive grid resistance”. The selection of the sensitive grid resistance should be based on the heat dissipation area of the strain gauge, the influence of the wire resistance, the signal-noise ratio and the power consumption consideration. The 350 Ω, 1000Ω resistance is normally recommended for sensor manufacturing. Large strain gauge resistance will reduce the impact of the lead wire resistance on the circuit sensitivity, and can improve the signal-noise ratio of the circuit. However, in the case of limited area, if the resistance is too high, the sensitive grid of the strain gauge turns to be particularly fine, which lead to much sensitive to any scratch, pinhole, gap, and the adhesion to the backing will be also declined, as the result the stability changes which will bring certain difficulties to manufacturing and operating.


ZEMIC offers strain gage with resistance that commonly used: 60Ω, 120Ω, 350Ω,500Ω,600Ω, 650Ω,750Ω,1000Ω, 1100Ω, 2000Ω, etc.

2. Sensitive grid length


The part on sensitive grid that can realize the transformation from strain value to electrical signals.


The grid length is an important parameter for strain gauge selection. The output of the strain gauge is the average strain within the area covered by the sensitivity grid. In the stress concentration area, the peak strain is often limited to a very small area. If the long sensitivity grid is selected, obvious measurement error will occur, as shown in Figure 2, the sensitivity decreases for the sensor.However, for short sensitivity grid (e. g., less than 3mm long), many performance will decrease, especially for strain limit creep, static measurement stability, and fatigue life.


Longer strain meters have many advantages, such as easy paste and wiring, good heat dissipation, and small power consumption per unit area.This is important for the strain gauge used on plastic and other specimens with poor heat transfer performance.Poor heat dissipation will cause a local high temperature on the sensitivity grid, backing, binder and specimen surface, which seriously affects the performance and accuracy of the strain meter.In addition, for non-uniform materials, such as concrete, cast iron, and cast steel, the grid length is generally required to be greater than the uneven size of the material in order to truly reflect the average strain in the structure.However, the grid length is not the longer the better.The performance of a strain gauge that is too long is not much improved, the quality of the paste is not easy to guarantee, and the cost of a strain gauge that is too short or too long is higher. In summary, for measurements on metal materials, strain gauges with a grid length of 3 to 6 mm are generally selected.

The shape of the sensitivity grid structure includes the shape, number and direction of the sensitivity grid, the size of the horizontal grid, the shape and distribution of the welding end, the lateral width of the sensitivity grid, etc. Now it is introduced by the strain gauge classification method of ZEMIC: Dividable It is a single-axis strain gauge, a multi-axis strain gauge and a compound strain gauge.


(1) The main feature of the uniaxial strain gauge is that it has a single sensitivity grid, which is used to measure the strain in the axis direction of the sensitivity grid. There are two types of structure: "AA" and "AB". Among them, the "AA" sensitivity grid is a uniaxial horizontal structure type; "AB" is a uniaxial 45° sensitivity grid structure type.


(2) The main feature of dual-grid strain gauges is that there are two sensitivity grids, and the axis of the two grids is 90° or 0° to each other. Generally, the stress or strain direction must be predicted in advance when using these strain gauges. The main structure types are "BB", "HA", "GB", and "FB". Among them, the two grids of "BB" are perpendicular to each other, that is, the "T" type strain gauge, which is mainly used to test axial strain and lateral strain (also called Poisson strain); the two grids of "HA" are perpendicular to each other at 90°, and the horizontal direction The “V” type strain gauge is mainly used to measure physical quantities such as shear stress and torque; the “GB” two grids are in the same axis and are mainly used to measure materials or materials that are in the same axis but in different directions of force. Structure. "FB" two grids are parallel to each other, mainly used to measure side-by-side different gradient stress or strain.


(3) Multiaxial strain gauges are also called strain rosettes. There are two or more sensitivity grids arranged in different directions on the same substrate to measure surface stress or point stress with unknown principal stress direction. Under normal circumstances, on the material that needs to determine the stress, stick a strain gauge to measure the stress or strain in three directions, and calculate the stress magnitude and stress direction through a specific calculation formula. The three axes have an angle of 45°, 60°. Or 120°, etc. The main structure types are "BA", "CA", "CC", "CAK", "CDK", "BC", and "CB". Among them, "BA", "CA" and "CC" are used to measure plane stress. "BC" and "CB" are used to measure point stress, and "CAK" and "CDK" are used to measure residual stress.


(4) The compound strain gauge is to arrange multiple sensitivity grids into the required shape on the same substrate and connect the circuit loop. It is mainly used for sensors. Such as round diaphragm (KA).