The "Strain-Gauge Thermocouple": A novel device for simultaneous strain and temperature measurement

A novel methodology for simultaneous strain and temperature measurements by means of an ac powered electrical resistance strain gauge connected to a s train conditioner using thermocouple wires is proposed and validated. To th is aim a specific device has been designed and implemented; the characteris tics of the electronic circuit for signal conditioning have then been teste d in order to determine the overall performances in temperature and strain measurements. The field verification of the method is conducted by imposing strain fields in the range from 0 to about 700 mum/m and temperature varia tions in the range from -10 to 100 degreesC. The difference between the str ain measured by the proposed device and the one evaluated by a conventional digital strain meter was always less than 4 mum/m while the mean temperatu re discrepancy was 0.5 degreesC with respect to the reference temperature m easured with a K-type thermocouple. Finally, compensation of temperature ef fects on the actual strain value has been performed while the temperature r anges from ambient to 100 degreesC with a residual error value of 1.4 +/-1 mum/m. (C) 2001 American Institute of Physics.