Non-contacting creep strain determination at 550 deg. C

The digital speckle correlation technique (DSCT) is a non-contacting and whole field displacement/strain measurement system that has been successfully applied to a variety of applications. The technique is based on correlating the speckle surface of the object before and after deformation. It is best suited for flat surfaces. Creep deformation may, however, cause decorrelation of the speckle surface. The ability of DSCT to measure creep displacement/strain fields at 550 deg. C using 2.25%Cr 1%Mo steel specimens was evaluated. The specimens were cylindrical so that the effect of a non-flat surface was also included. Results show that DSCT can measure creep displacement and strain fields under laboratory conditions with less than 5% error. Further research and development work are required to assess the applicability of DSCT for creep displacement/strain measurements under field conditions