Nowhere are there such important and general purpose tools in precision engineering and measurement as strain gauges.
These miniature but mighty devices are the quiet leaders of many of the technologically amazing developments with which we now associate daily life.
This guide is an all encompassing overview of the strain gauge world. We’ll cover how they work, the different types of strain gauges, and the many ways they are used across a variety of industries.
What are the Strain Gauges
Well, the Strain gauges are transducers that can provide a measurement of the change in dimension of an object. Which can be a quantity called strain. It’s very important to understand how materials behave under a variety of conditions.
Moreover, the strain gauges are mostly composed of metal foil/thin metal or can be semiconductor material. Their attachment to the object whose deformation measurement is being taken gives rise to good and accurate measurements.
Any deformation that is caused in the object by external forces, such as stress or pressure, induces strain on the gauge.
Therefore, this deformation results in changes in the resistance of the resistance gauge. It is built on this principle that strain gauges can find application.
The application of this data ranges from checking the structural integrity of a building to material testing and optimization.
Types of strain gauges
Strain gauges come in different types and each one comes with designed to meet the needs for measurement and also the environmental conditions.
Metal foil strain gauge
This is one of the most common types of strain gauge which is the metal foil strain gauge. It’s been constructed using thin metal foils that are typically constantan or nichrome, which are bonded to a flexible backing material.
For the purpose of their function, when an object to which the gauge is attached is strained, it simply causes the metal foil material to deform, thereby changing the resistive nature of the metal foil.
The change thereafter is measurable and translatable into full usable strain features, rendering them highly reliable in a varying number of applications.
Semiconductor strain gauge
Another type of strain gauge is the semiconductor strain gauge, which uses the piezoresistive effect in materials such as silicon or germanium.
Semiconductor strain gauges are much more sensitive to strain than metal foil gauges, and are therefore used in applications that require very precise measurements.
The gauge factor of a semiconductor strain gauge is also typically much higher than that of a metal foil gauge.
This increased sensitivity to strain also makes semiconductor strain gauges more sensitive to temperature changes, so they require careful temperature compensation and calibration.
Piezoresistive strain gauges
Piezoresistive strain gauges are designed to respond to mechanical stress by altering their electrical resistance.
Their high sensitivity allows for the detection of even the smallest deformations, making them an excellent choice for applications demanding precision.
In contrast, capacitive strain gauges measure changes in capacitance between conductive plates as strain alters the distance between them.
This type of gauge is especially valuable for applications that involve the measurement of dynamic strain, such as vibration analysis.
Understanding the various types of strain gauges and their unique characteristics is essential for selecting the most appropriate tool for specific measurement requirements.
Factors to consider when selecting a strain gauge
Choosing the right strain gauge is an important decision that can affect the accuracy and reliability of your measurements.
- The material and design of the strain gauge are the most important factors to consider. Different materials have different sensitivity to strain and environmental conditions.
The design of the gauge, including its size, shape, and backing material, also plays a role in determining its suitability for specific applications. - The nature of the strain being measured is another critical factor. Strain gauges are designed to measure either static or dynamic strain.
Static strain gauges are ideal for applications where the strain does not change rapidly, such as in civil engineering structures and pressure vessels.
Understanding the type of strain your application involves will help you choose a gauge that can provide accurate and reliable data. - The environment in which strain gauges are placed can also have a significant impact on their performance. Factors such as temperature, humidity, and electromagnetic interference can all affect the accuracy of strain measurements.
Some strain gauges are specifically designed to operate in harsh environments, with features like temperature compensation and shielding to minimize interference.
It’s important to consider the environmental conditions of your application and select a strain gauge that can operate accurately in those conditions. - In addition to technical specifications, practical considerations such as budget and availability are key. Strain gauges span a wide range of costs, and while top-tier models may offer advanced features and performance, they may not always be necessary for every application.
Moreover, considering the ease of installation and compatibility with existing measurement systems can lead to time and resource savings in the long term.
In conclusion, the selection of the appropriate strain gauge necessitates a thorough examination of the gauge’s material and construction, the strain’s characteristics, and the environmental conditions that may influence its efficacy.
By weighing these technical factors with practical considerations such as budget and accessibility, one can ensure the selection of a strain gauge that not only meets the application’s demands but also delivers consistent and precise measurements over time.
