Thermal output observations from Fe-Ni-Cr metal foil strain gages

Abstract

Fe-Ni-Cr alloys have been used for more than 40 years to manufacture metal foil strain gages for specific applications. The main characteristics of this metal are high gage factor, high fatigue strength, and high thermal output. To circumvent the effect of high thermal output, typical applications in stress analysis have involved dynamic loading where the high gage factor and fatigue strength could be used to advantage and the effect of thermal output could be minimized or ignored. Typical applications in precision transducers have also involved dynamic loading and/or careful exercise of Wheatstone bridge circuit cancelation of like-thermal output in adjacent arms. In this paper, we report uniform thermal output variation in Fe-Ni-Cr metal foil strain gages. Quarter bridge and half bridge thermal output data are presented, which illustrated the suitability of this type of strain gage for stress analysis and precision transducers even when loading conditions are not dynamic. © The Society for Experimental Mechanics, Inc. 2014.