Geosense VWS-2100 series vibrating wire embedment strain gauges are designed for direct embedment in concrete. The strain gauge operates on the principle that a tensioned wire, when plucked, vibrates at its resonant frequency. The square of this frequency is proportional to the strain in the wire.
The gauge consists of two end blocks with a tensioned steel wire between them. Around the wire is a magnetic coil which, when pulsed by a vibrating readout or data logger interface, plucks the wire and measures the resultant resonant frequency of vibration.
Deformation within the concrete will cause the two end blocks to move relative to each other. The tension in the wire between the blocks will change accordingly, thus altering the resonant frequency of the wire.
The VWS-2125 model can be used within mass concrete with coarse aggregates as its heavy duty construction resists bending, and the large end flanges provide a high contact area.
VWS-2000 vibrating wire strain gauges may be read by the VW-2106 or any vibrating wire readout device and may be readily data logged using the Campbell Scientific CR-series, Cautus Geo’s Cautus Logger CL1 or any other data loggers with vibrating wire interface modules.
Vibrating wire strain gauges output a frequency signal, and are therefore insensitive to resistance changes in connecting cables caused by contact resistance or leakage to ground.
Cable may be readily and simply extended on site without special precautions. Gauges may be read up to 1000 meters away from their installed location without change in calibration.
VWS-2100 strain gauges are fully waterproof all stainless steel construction with coils encapsulated with epoxy resin. The protective tube assembly is totally sealed to the embedment flanges by laser welding, thus eliminating any possibility of seal degradation. During the testing and stressing procedures, the welds are fully checked by tensile testing carried out in excess of the elastic limit of the protective tube assembly.
Strain gauge rosettes and zero strain containers are available for VWS-2100 gauge series.
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Gauge length: VWS-2100: 150 mm; VWS-2120: 50 mm; VWS-2125: 250 mm
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Overall length: VWS-2100: 156 mm; VWS-2120: 54 mm; VWS-2125: 260 mm
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Resolution: 1 µε
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Strain range: 3000 µε
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Accuracy: ±0.1% to ±0.5% FS
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Non linearity: <0.5% FS
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Operating temperature range: -20 to +80°C
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Frequency range: VWS-2100: 850-1550; VWS-2120: 1500-3500; VWS-2125: 1500-3500
