Wave-shaped wire extensometer for linear displacement measurement

This article presents the concept and the method of operation of an innovative device for the measurement of relative displacements, and a study of its metrological properties. The mechanical system of the proposed measuring instrument is similar to the systems of existing wire displacement transducers. The construction of previously known devices for measuring relative displacements containing a measuring wire (wire strain gauges, wire dilatometers) involves direct attachment of the wire to the anchors of the device, through either additional elastic elements or mechanical transmissions. In this measuring instrument, the elastic sensor element has been replaced with a wavy wire that is attached directly to the anchors of the device. The measuring range of this device is four times as large as that of a wire displacement transducer with a measuring base of the same length. The increased measuring range will enable the use of this equipment for measuring relative displacements of building elements in the range 2–3 mm, with a measurement uncertainty of 0.025%.