Abstract
In wire strain gauges constantan filaments (dia. 0.025 mm) have been used as the resistant wire grid. Ordinary paper-base gauges may be used at room temperature. If the application involves the use of strain gauges at higher temperatures, a change of the electric resistance takes place during the strain measurement by the fluctuation of the measuring temperature. Even at room temperature a considerable difference between the resistance of the active gauge and that of the dummy gauge occurs due to the difference in the temperature characteristics of the gauges in no-load condition leading to zero-shift errors. Generally the temperature characteristics of gauges depend upon the thermal coefficient of resistance and the thermal expansion coefficient of the wire grid and the thermal expansion coefficient of the material to be tested. The purpose of this paper is to show the relationships between these factors and the temperature range in which strain gauges made of constantan wire grid can be used.
