‘SPATE’ stress studies of plates and rings under in-plane loading

In this paper, a new experimental, computercontrolled, stress-analysis technique (SPATE) based on the measurement of infrared emissions from the surface of a cyclically loaded body, has been used to study the stress distributions in rectangular steel plates and circular rings under cyclic in-plane loading. A typical test procedure for quantitative stress measurement is described. The effects of surface obliquity and the thickness of the paint coating applied to the specimen surface on the received signal are described and discussed. Results are given for three series of test specimens and compared quantitatively with relevant theoretical solutions. Attention is drawn to the changes in the received signal as the applied load range increases beyond the elastic limit of the material. A new application of the technique to the determination of the stress-intensity factor in acracked body is also illustrated. Paper was presented at the 1985 SEM Spring Conference on Experimental Mechanics held in Las Vegas, NV on June 9–14