Automotive Manual PDF

VW Embedment Strain Gauges are used to measure strain in reinforced concrete and mass concrete.
Operation
The body of the strain gauge is a steel tube with flanges at either end. Inside the body, a steel wire held in tension between the two flanges. Strain in the concrete causes the flanges to move relative to one another, increasing or decreasing the tension in the wire.
The tension in the wire is measured by plucking the wire with
electromagnetic coils and measuring the frequency of the resulting vibration. Strain in the wire is calculated by squaring the frequency reading and multiplying a gauge factor and a batch calibration factor.
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