What causes the temperature error of strain gauges and what are the methods to reduce or compensate for the temperature error?
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What causes the temperature error of strain gauges and what are the methods to reduce or compensate for the temperature error?

Posted Date: 2024-02-05

What causes the temperature error of strain gauges and what are the methods to reduce or compensate for the temperature error?

Temperature error refers to the difference between the temperature obtained by the strain gauge during the measurement process and the actual temperature. There are many reasons for the temperature error of strain gauges, including thermal expansion of materials, displacement and deformation caused by temperature gradients, and changes in resistance temperature characteristics.

First of all, the thermal expansion of materials is an important reason for the temperature error of strain gauges. As the temperature increases, the material in the strain gauge will thermally expand, causing the geometry of the strain gauge to change, thus affecting the measurement of the resistance value. In addition, due to different thermal expansion coefficients of materials, the temperature change rates of different parts will also be different, resulting in a temperature gradient in the strain gauge, further increasing the temperature error.

In addition, temperature gradients can also cause displacements and deformations in the strain gauges, resulting in temperature errors. Temperature gradients expose different parts of the strain gauge to different temperature environments, causing uneven thermal expansion of the material. The uneven expansion of this material causes internal stress and strain in the strain gauge, which in turn causes displacement and deformation of the strain gauge, ultimately affecting the resistance measurement.

In addition, the change in the temperature characteristics of the resistance is also an important reason for the temperature error of the strain gauge. The temperature characteristics of a resistor refers to the law in which the resistance value changes with temperature. Normally, the temperature coefficient of resistance is positive, which means that as the temperature increases, the resistance value increases. However, the temperature coefficient of resistance of different types of strain gauges is not the same, and the temperature coefficient of resistance also changes with temperature. Therefore, if the temperature characteristics of the resistor are not corrected during the measurement process, a large temperature error will occur.

In order to reduce or compensate for the temperature error caused by the strain gauge, the following methods can be adopted.

First, choose the material and structure of the strain gauge reasonably. Reasonable selection of strain gauge materials can reduce temperature errors caused by thermal expansion. Typically, temperature errors can be reduced by choosing materials with smaller thermal expansion coefficients. At the same time, rationally designing the structure of the strain gauge, such as strengthening the support structure, adding cooling devices, etc., can reduce the displacement and deformation of the strain gauge during temperature changes, thereby reducing the temperature error.

Secondly, the temperature error generated by the strain gauge is reduced by reducing the temperature gradient. The temperature gradient of the strain gauge can be reduced by setting up an insulation layer around the strain gauge and adding cooling devices. Reducing the temperature gradient can reduce the displacement and deformation caused by thermal expansion, thereby reducing the temperature error.

In addition, the temperature error can be reduced by compensating for changes in the temperature characteristics of the resistor. The resistance-temperature curve can be established by measuring the change of resistance with temperature in advance, and then correcting the resistance value according to the actual temperature during the measurement. This eliminates temperature errors caused by changes in resistor temperature characteristics.

In addition, a temperature compensation circuit can also be used to reduce temperature errors. The temperature compensation circuit usually connects a temperature sensor to a strain gauge, and compensates the temperature of the strain gauge by measuring the temperature of the temperature sensor. In this way, the resistance value of the strain gauge can be corrected based on the measurement results of the temperature sensor and the temperature error can be reduced.

To sum up, the causes of temperature errors in strain gauges mainly include thermal expansion of materials, displacement and deformation caused by temperature gradients, and changes in resistance temperature characteristics. In order to reduce or compensate for temperature errors, the material and structure of the strain gauge can be reasonably selected, the temperature gradient can be reduced, changes in the temperature characteristics of the resistance can be compensated, and temperature compensation circuits can be used. These measures can effectively reduce the temperature error caused by the strain gauge and improve the accuracy and reliability of the strain gauge measurement.


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