INVESTIGATION OF A WELDABLE TYPE, HIGH-TEMPERATURE STRAIN GAGE FOR MEASUREMENT OF STRAIN BY ELECTRICAL MEANS AT TEMPERATURES UP TO 600 F

An investigation was conducted to determine whether or not a weldable strain gage could be used to measure high thermal strain on structural steel members at temperatures up to 600/sup o/F. The gages as received from the manufacturer required temperature cycling before their change in resistance with temperature became repeatable. After gages were cycled and stabilized, the resistance of some gages increased with temperature whereas that of others remained close to their initial value or decreased. Thus random selection of gages for temperature compensated bridges could result in considerable mismatch. The tests indicated that unbonded strain data can be used to predict the apparent strain of bonded gages to within 0.07 to 0.4 micro-in./in.//sup o/F for temperatures up to 600/sup o/F. Gage factors were found, in general, to be lower than those specified by the manufacturer and to decrease from 2.5 to 7.5% with temperature at 600/sup o/F. (auth)