The dynamic stress-strain relation of annealed 2S aluminum under compression impact

Abstract

This thesis presents the results of a study of the stress-strain relation of a metal when subjected to compression impact. An annealed 2S aluminum is used for this investigation. Two methods of securing the dynamic stress-strain curve are considered; namely, from the measurement of impact stress and of maximum plastic strain as functions of the impact velocity from 3.15 to 125 ft/sec. The dynamic stress-strain relations obtained by these methods are compared with the static stress-strain curve. Both of the dynamic stress-strain relations lie considerably above the static curve. However, the two dynamic relations are not coincident which indicates that a single dynamic stress-strain curve cannot properly describe the behavior of the material for all impact velocities. A family of stress-strain curves is postulated in order to explain the difference between these two relations. Each curve of the family depends upon the final strain or impact velocity. It is further concluded that the rise of the stress-strain curve under dynamic loading cannot be induced by moderate loading rates.