Strain gauge thermal compensation: approaches and new improvements

The present paper deals with strain gauge thermal compensation strategies, with the aim of reducing to a minimum the measurement errors due to thermal effects. In the paper a survey of various techniques used to compensate these thermal effects is reported, along with some experimental activities performed in order to improve the installation processes. Particular attention was devoted to the analytical approach and to the dummy gauge technique, highlighting the difficulties for composite materials. As for the analytical approach, a deep description was made for the measurement of the coefficient of thermal expansion (CTE) directly by means of strain gauges, whose precise identification is crucial. Referring to the dummy gauge technique instead some experiments have been performed in order to test a new installation process and solution that could guarantee reducing measurement errors. The results show that the dummy gauge technique is the most suitable for the present case: the instrumentation installed on the wing of the Next Generation Civil Tiltrotor under development by Leonardo Helicopters Division within Clean Sky 2 Fast Rotorcraft Aircraft Demonstrator Platform.