OPTICAL METHOD TO STUDY MATERIAL BEHAVIOUR AT HIGH STRAIN RATES

摘要

An optical technique to study material behaviour at high strain rates is presented. A small specimen is subjected to a rapid tensional loading in a Hopkinson bar type of arrangement where the loading is measured in the bar following the specimen. A high-speed camera of the image converter type is used to acquire time-resolved images during the loading. These images are evaluated using digital speckle photography to give the in-plane strain field. A calibration procedure is included that compensates for the aberrations in the camera. Experimental results on mild steel are further compared with a finite element calculation with the result that both strain fields show the same general behaviour, but some discrepancies appear that need to be further analysed in the future.