A long-term local deformation measurement system for notched specimen at high temperature

This paper describes the design and evaluation of a novel optical instrumentation system that has been developed for measuring high temperature creep deformation under long-term loads. The system includes short optical fibers, a super long working distance microscope, a CCD camera, and digital image processing software. Short optical fibers are pasted on the small region on one side of the specimen surface as markings. The two optical fibers are illuminated by a light and are focused onto the CCD camera by the super long working distance microscope. The images tracked at intervals are processed by digital image processing software. The distance between the fibers at each picture can be measured. The local creep deformations versus time are obtained by measuring the variation of relative distance between the fibers. Experiments on Cr5Mo notched specimens were carried out. The results demonstrate that the system is capable of measuring creep deformation at elevated temperature.