Plastic Waves of Combined Stresses Due to Longitudinal Impact of a Pre-Torqued Tube

摘要

Experiments are reported in which annealed aluminum tubes are subjected to a static plastic torque followed by a longitudinal compressive impact. Measurements are made of both longitudinal and shear strain-time profiles at stations along the specimen. Qualitatively, the strain response at the gages corresponds to the arrival of a fast wave for which shear strain decreases while longitudinal strain increases followed by a slow wave for which both shear and longitudinal strains increase. A rate independent theory of combined longitudinal and torsional plastic wave propagation for workhardening materials is found to be adequate for predicting many features of the observed strain-time response in the specimens. For the particular case of an isotropic workhardening, elastic-plastic material, numerical solutions of the governing equations are compared with the results of the experiments. The same assumed material behavior is used for comparing observed behavior at unloading waves with theoretical predictions. Discrepancies are shown to be explainable in terms of the inadequacy of the assumption of strain-rate independent behavior. (Author)