How to choose the strain gauge in stress test
Selecting the right strain gauge in the stress test is critical to the correctness of the test results.
For single-digit microstrain measurements, the correct choice is to use foil-type strain gages. Although semiconductor strain gauges have good stability, they can easily cause many errors under certain conditions, such as temperature changes and light changes.
Foil strain gages are based on the theory that changes in length cause corresponding changes in resistance. With the Wheatstone bridge, the change in resistance produces a highly accurate, highly reliable measurement signal. The material of the strain gage wire is generally constantan, and sometimes it may be nickel-chromium alloy. Strain gauges have different resistance, length and size.
1. For composite and non-homogeneous materials, the longest possible strain gauge should be selected. Longer lengths can capture the overall average strain of the material.
2. For wet environments, choose the strain gauge with the lowest resistance. The lower resistance can offset the errors caused by the swelling of the insulator due to moisture.
3. If you know the strain direction, use a single straight piece. If you are not sure, you should use a strained flower. It can measure uniaxial, biaxial and shear stress.
4. For areas where there are a lot of irregularities and stress concentrations around the stress test , select the smallest possible strain gauge and you can get real test results.
5. For humidity - temperature applications, it is better to use Constantan base strain gages. For temperatures above 200°C , nichrome strips should be selected. It must be ensured that there is no damp air on the installation surface of the strain gage. Even at 72°F , metal will heat up in the sun.
6 , for the need for long-term stress testing, use nickel-chromium alloy strain gauges. It has a higher fatigue life.
7. Using encapsulated strain gages, the encapsulated strain gages can be better protected against damage during operation.
8. Strain gages with built-in leads can not only save installation time, but also reduce the damage of the corresponding transformer during installation.
For more information, please pay attention to Nanjing Juhang Technology Co., Ltd. and call the hotline for consultation.
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