A strain gauge is a device used to determine the amount of strain, or change in dimensions, when stress is applied. Strain gauges measure mechanical quantities by converting tension, force, and pressure into an electrical signal.
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Applications of Strain Gauges
Strain gauges can be used for measuring temperatures, detecting cracks, propagating cracks, extensometer, residual stress, transducer gauge, and shear modulus gauge, among other applications.
Strain gauges are often utilized in a variety of industries, including:
- Marine Biology
- Automotive Manufacturing
- Industrial Manufacturing
- Tooling and CNC Machining
Strain Gauge Design and Function
The strain gauge, also known as the strain gage, is best known as the sensory aspect of a load cell. Load cells measure the compression, tension, and/or shear force of various materials, including solid objects, liquid, and gas. The strain gauges are the essential part of the load cell, as they are what detect the inconsistencies in a substance and turn that into an electrical signal, which is then translated through a computer as a readable measurement. When part of a load cell, there are multiple strain gauges being used, connected by circuits that pass along the electric signal. Having multiple strain gauges make up the load cell is important because the more present for a single reading, the more precise the reading will be. Strain gauges are also often a part of the force transducer systems, which serve just about the same purpose at load cells.
The most common types of strain gauges are piezoresistive or semiconductor, bonded metallic wire, carbon-resistive, and foil gauges. In particular, the foil gauge looks like a flathead version of a spatula, without the arm or body. It has a flat surface, which can be adhered to the body of the material it is measuring. The electrical resistance in each type of strain gauge varies linearly with strain. Typical characteristics of strain gauges are lead wire, solder tabs, ribbon leads, cryogenic use, encapsulated, embeddable, waterproof, and weldable. These sensors can be substituted with piezoelectric crystals. However, the variety of strain gauge styles allow for consumers to pick the one that will best suit the substance they need to measure.
Factors to Consider When Purchasing Strain Gauges
The operating temperature, state of strain, and amount of stability needed are important factors when choosing a strain gauge. The gauge factor, gauge length, nominal resistance, and strain sensitive material must also be considered.