A video technique for obtaining corrected true compressive stress

Summary

A modification of the method of Watts and Ford is presented, which, when combined with the utilization of a video camera, allows standard compression tests to yield reliable true compressive stress versus strain data. The video images permit diameter measurements to an uncertainty of less than one percent. If radial asymmetries are minimized by proper consideration of end effects, area uncertainties of less than two percent can be achieved. Furthermore, if replicated experiments and statistical calculations are used at each step in the data reduction, one can determine the maximum uncertainty associated with the final true stress versus strain data.