It has gauge lengths of 50 to 2000 mm and a discrimination of only two microstrains on the 200mm gauge. This makes the DEMEC strain gauge ideal for strain measurement and crack monitoring on many different types of structures.
The DEMEC strain gauge consists of an invar main beam with two conical locating points, one fixed and the other pivoting on a special knife edge. The points sit in pre-drilled stainless steel discs which are attached to the structure with adhesive. The pivoting point’s movements are measured by the strain gauge which is attached to a base plate on the invar beam. Thermal movement within the instrument is negligible.
With practice, 200 strains per hour can be measured with accuracy of about ±5 x 10-6 under most laboratory test conditions. Even greater accuracy has been obtained using the gauge in its ideal horizontal position. In development tests of this kind 90 per cent of measured strains were within ±3 x 10-6 of the mean.
The digital version of the DEMEC strain gauge incorporates a digital indicator with a resolution of 0.001mm, zero set, preset and output for SPC. The indicator can be connected to a data processor for recording and analysis of results. The indicator displays spindle movement digitally by means of a linear encoder and has a response speed of 1000 mm per second. The digital DEMEC is battery operable.
DEMEC strain gauges come complete with an invar reference bar, for control measurements, and a setting out bar for accurate positioning of locating discs.
The DEMEC strain gauge is available in Australia and New Zealand from Bestech Australia Pty Ltd