Strain Gauge Basics – Part 2 – Shunt Calibration

As mentioned in the previous post, in order to relate the measured voltage difference across the bridge circuit to a strain measurement, we need a way of calibrating the system. In most systems, including the Prosig acquisition systems, this is done by including a high-precision shunt resistor across one of the legs in the bridge. For example, the following diagram shows a quarter-bridge circuit with a shunt calibration resistor, RS, across the bridge completion resistor R2.

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How to avoid a ground loop – It’s not only a problem with accelerometers

When using modern, high technology measurement devices one can often be tripped up by the simplest things. The most common is the ground loop. Time and again this issue rears…

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Comparison Between Sound Intensity Probes and Acoustic Cameras

Sometimes we are asked about the differences between an acoustic camera and a sound intensity probe and which of the two is better for a particular application. There is no straightforward answer as they are quite different pieces of equipment, used for measuring different things. An acoustic camera is a tool used to locate and analyse sound sources, usually both steadystate and dynamic phenomena. The intensity probe is used to find the sound intensity at a particular position, usually a steadystate phenomena.

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What Is A Strain Gauge?

A strain gauge is an electrical sensor which is used to accurately measure strain in a test piece. Strain gauges are usually based on a metallic foil pattern. The gauge is attached to the test piece with a special adhesive. As the test piece is deformed, so the adhesive deforms equally and thus the strain gauge deforms at the same rate and amount as the test piece. It’s for this reason that the adhesive must be carefully chosen. If the adhesive cracks or becomes detached from the test piece any test results will be useless.

Strain gauges are used not just for metals; they have been connected to the retina of the human eye, insects, plastics, concrete and indeed any material where strain is under investigation. Modern composite materials like carbon fibre when under development are often constructed with strain gauges between the layers of the material.

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