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What is a strain gauge
Nov 01, 2017

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What is a strain gauge 

The strain Gage is composed of a sensitive gate and other components for measuring strain. The working principle of the resistance strain Gage is based on the strain effect, that is, when the conductor or the semiconductor material produces mechanical deformation under the action of external force, the resistance value correspondingly changes, this phenomenon is called "strain effect".


The semiconductor strain Gage is made of semiconductor materials and its working principle is based on the piezoresistive effect of semiconductor materials. The piezoresistive effect is the phenomenon that the resistivity of a semiconductor material is changed when an axial force is subjected to external forces.


The strain Gage is composed of a sensitive gate and other components for measuring strain, when it is used, it is firmly pasted on the measuring point of the component, the strain of the sensitive gate is changed and the resistance changes due to the deformation of the measuring point, and then the resistance is changed by the special instrument, and the strain value of the measuring point is converted.


Metal resistance strain gage variety, various forms, common with wire resistance strain gage and foil-type resistance strain gage.


The foil resistor strain gage is a sensitive element, which is based on the strain-resistance effect, and the metal foil is used as the sensitive gate to convert the strain of the tested parts into the resistance variation.


Optical strain gauges are generally manufactured using a Bragg grating glass fiber not exceeding 4-9 microns in diameter.

In general, a person's hair diameter is 60-80 microns. The fiber core is surrounded by a pure glass covering of about 125 microns in diameter.


The strain gage based on Bragg grating has the following advantages:


1. Insensitive to electromagnetic fields

2. Environments that can be used for explosions

3. In the case of high vibration load, the material (glass) will not cause malfunction

4. A larger strain can be measured, and the maximum strain of the general resistance strain Gage is hundreds of micro-strain, while the maximum strain of the optical strain Gage is 7000 micro-strain.

5. Fewer connectors, resulting in less interference with test objects

6. Interconnection requires a large number of sensors, and different Bragg wavelengths can be integrated in one fiber.