Strain Gauges – What are they and how do they work?

What are strain gauges?

Strain gauges are measuring devices that measure the deformation of a material, usually caused by an applied force or stress. They are usually thin metal foils covered with conductive paths. When a material is stretched or compressed, the sensor changes its electrical resistance, which can be converted into a force or stress value.

The most common type of strain gauge is the resistance strain gauge, which works by changing the resistance of a conductor in response to its deformation.

How do strain gauges work?

Strain gauges work on the principle of a physical phenomenon called the piezoresistive effect. It consists in the fact that under the influence of deformation (stretching or compression), the conductor changes its electrical resistance. It is this change in resistance that is converted by appropriate devices into an electrical signal proportional to the applied force.

Strain gauges are usually mounted on the surface of objects or built into their structure. When the object is subjected to forces, the strain gauge deforms with it, and the change in its resistance is read by the measuring system.

Types of strain gauges

Strain gauges come in various forms, and their selection depends on the specific application and measurement requirements. Here are the most popular ones:

1. Foil strain gauges - made of thin metal foil, glued directly to the surface of the tested material. They are the most common and versatile.

2. Semiconductor strain gauges - are characterized by greater sensitivity, which allows for more accurate measurements, but are more sensitive to temperature changes.

3. Quartz strain gauges – used where extreme precision is required, such as in research or aviation equipment.

Applications of strain gauges

Strain gauges are essential in many industries and engineering, and their applications include:

1. Measuring forces and loads – strain gauges are used in the construction of industrial scales, measuring forces in machines, or monitoring loads on structures such as bridges.

2. Monitoring deformations in construction – strain gauges mounted on structural elements allow engineers to monitor the stability of buildings, bridges, or tunnels, allowing potential problems to be detected in time.

3. Biomedical engineering – strain gauge force sensors are used in prostheses, medical robotics, and in research on the forces acting on bones and joints.

4. Material research and testing – strain gauges allow for measuring stresses in materials during strength tests. They can be used to precisely assess how materials behave under the influence of different loads.

Advantages of strain gauges

Strain gauges have many advantages that make them a popular solution in measurement applications:

- High precision – they enable very accurate measurements of forces and deformations.

- Small size – they are very small and lightweight, which allows them to be mounted in hard-to-reach places.

- Versatility – they can be used in various conditions and to measure different types of stresses.

Challenges and limitations

Despite their numerous advantages, strain gauges also have some limitations. First of all, they are sensitive to temperature changes, which can lead to measurement errors. Therefore, in many applications it is necessary to use temperature compensation. Additionally, the installation of strain gauges requires high precision and proper surface preparation to avoid errors in readings.

Summary

Strain gauges play a key role in engineering, industry and scientific research. They enable precise monitoring of forces and stresses in various structures and devices. Selecting the right strain gauge depends on the specific requirements of the application, but their versatility makes them an indispensable tool in many fields.

If you need accurate force or strain measurements, strain gauges are a proven and effective solution.