An experimental investigation on parameters influencing infrared strip gauges to perform thermoelastic stress measurements

Abstract

Infrared strip gauges (IRSGs) are strips of metal bonded to the component surface at their ends, with the central portion unbonded. A single thermoelastic measurement performed with an infrared camera is expected to be able to precisely read the stress component indicated by every IRSG, thus allowing for stress separation in thermoelastic stress analysis measurements. This paper summarizes the results obtained using IRSGs on several materials, in an experimental campaign aiming at evaluating the influence of different parameters on the accuracy of IRSGs' strain measurements. The majority of the results showed a considerable underestimation of the stress caused by the shear deformation of the glue bonding the IRSGs' ends to the component surface. The experimental evidence has been supported by a mathematical rheological model.