Calculating Tensile Stress Using a Strain Gauge

In summary, a strain gauge is a device that measures strain in a material, which can be used to calculate tensile stress. The formula for calculating tensile stress using a strain gauge is strain multiplied by the modulus of elasticity, divided by the gauge factor. The gauge factor is a calibration constant that must be considered for accurate measurements. A strain gauge can be used to measure tensile stress in most materials, but the material must have some electrical conductivity. Factors such as temperature changes, improper installation, and external forces can affect the accuracy of the measurement and should be carefully controlled.
  • #1
orla22
22
0
A strain gauge has a unstrained resistance of 120 ohms, gauge factor of 2.0 is connected to steel girder so it experieces tensile stress. If strained resistance of gauge is 120.13 ohm. How do i calculate the tensile stress value?
 
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  • #2
The Gauge Factor is the ratio of the resistance change to the strain change. In this case, the relative change of the resistance of the gauge is twice as large as the strain of the sample.
 
  • #3


To calculate the tensile stress value, we can use the formula:
Stress = (Strain Gauge Resistance - Unstrained Resistance) / Gauge Factor

In this case, the strain gauge resistance is 120.13 ohms and the unstrained resistance is 120 ohms. The gauge factor is given as 2.0.
Plugging these values into the formula, we get:
Stress = (120.13 ohms - 120 ohms) / 2.0
= 0.065 ohms / 2.0
= 0.0325 ohms

Therefore, the tensile stress value is 0.0325 ohms. This means that the steel girder is experiencing a tensile stress of 0.0325 ohms, which is a measure of the force per unit area that the material is being pulled apart.
 

1. How does a strain gauge measure tensile stress?

A strain gauge is a device that measures the amount of strain or deformation in a material. When a tensile stress is applied to a material, it causes the material to stretch or elongate. This stretching causes a change in the electrical resistance of the strain gauge, which can be measured and used to calculate the amount of tensile stress being applied to the material.

2. What is the formula for calculating tensile stress using a strain gauge?

The formula for calculating tensile stress using a strain gauge is: tensile stress = (strain * modulus of elasticity) / gauge factor. The strain can be measured using the strain gauge, the modulus of elasticity is a material property, and the gauge factor is a calibration constant for the specific strain gauge being used.

3. How does the gauge factor affect the accuracy of the measurement?

The gauge factor is an important factor in ensuring the accuracy of the measurement. It is a calibration constant that is specific to the strain gauge being used and takes into account the material properties of the gauge. If the gauge factor is not properly accounted for, it can lead to inaccurate measurements of tensile stress.

4. Can a strain gauge be used to measure tensile stress in all materials?

Yes, a strain gauge can be used to measure tensile stress in most materials. However, the material must have some electrical conductivity in order for the strain gauge to work. Non-conductive materials, such as rubber, cannot be measured using a strain gauge.

5. Are there any factors that can affect the accuracy of the measurement when using a strain gauge?

Yes, there are several factors that can affect the accuracy of the measurement when using a strain gauge. These include temperature changes, improper installation of the strain gauge, and external forces or vibrations that may affect the material being measured. It is important to carefully consider and control these factors in order to obtain accurate measurements of tensile stress.

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