Strain Gauges

The strain gauge has been in use for many years and is the fundamental sensing element for many types of sensors, with the most common type being the electrical resistance strain gauge.

Electrical Resistance Strain Gauges

The majority of strain gauges are foil types which are available in a wide selection of shapes and sizes to suit a range of applications. They consist of a pattern of resistive foil mounted on a backing material and attached or bonded onto the surface of the object being measured. They operate on the principle that as the foil is subjected to stress, the resistance of the foil changes is a defined way. This resistance is measured to give the change in strain.

Advantages of Electrical Resistance Strain Gauges

• Can be very small so can be used to measure the stresses in very small items/components
• Can be used in demanding environments
• Good sensitivity
• Suitable for static and dynamic measurements
• Cost effective

Vibrating Wire Strain Gauges

Vibrating wire strain gauge are welded to or embedded in various structures to measure strain. Each strain gauge consists of two end blocks with a tensioned steel wire between them. As the steel or concrete undergoes strain, the end blocks move relative to each other causing the tension in the wire to change and therefore altering the resonate frequency of the wire, which is measured to establish the strain in the instrument. For further details on the range of vibrating wire strain gaugues supplied, please visit www.geokon.com

Advantages of vibrating wire strain gauges:

• Frequency output is immune to electrical noise
• Is able to tolerate wet wiring common to geotechnical applications
• Capable of signal transmission for several kilometres without loss of signal
• Rugged and reliable

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