Day, Emmett E.
University of Washington, Seattle, Wash.
Pages: 9 Published: Jan 1958
With the growing necessity for measuring strain at elevated temperature, a great deal of work has been concentrated upon the development of a suitable gage for the purpose. This effort has mostly been toward changing the room temperature type gage to adapt it to high-temperature application by using suitable cements, grid backing, element materials and other changes. Several organizations have been active in this development work, and the result has been that a variety of types are available commercially for which many claims are made to success in obtaining desirable characteristics. Laboratory evaluation of six types of commercial gages has been the subject of this investigation which was carried on during the summer of 1957 in the Structures Test Laboratory of the Chance Vought Aircraft, Inc. The performance of the gages was studied in an effort to determine the following: (1) gage factor change with temperature; (2) zero shift with time at temperature; (3) indicated strain at temperature for gages wired to compensate each other for temperature; and (4) indicated strain at temperature for gages not wired to compensate each other. Attempts were made to arrive at a maximum operating temperature for which reliable results could be expected. The target temperature was 1200 F but, with the best setup available it was soon decided that 900 F was a practical upper limit for testing due to the large change in modulus of the beam material. As the temperature went higher, the strains had to be reduced to undesirable minimums to stay within the elastic range of the beam material.
Paper ID: STP45028S