Study On Recorded And Controlled Deformations Of Pure Copper Bars Under Impact Tension

1) A tensile split-Hopkinson bar (TSHB) was optimized in the first loading duration to make effective measure for the stress, strain and strain rate in specimens, and thermoviscoplastic models in a certain range of strains for a pure copper were determined.2) The deformations of pure copper bars during the multi-tensile loading including necking in optimized TSHB tests were recorded by a high speed camera, and were used in adjusting determined thermoviscoplastic models to describing large strains.3) A high-speed tensile facility (HSTF) with special fixtures was designed and numerically simulated to interrupt tests for pure copper bars controlled locally at different levels of elongation. The results of scanning electron microscopical (SEM) investigation of recovered pure copper specimens were shown to clarify damage evolution within elongation-controlled parts of specimens.4) The recorded strains at diffuse necking of pure copper bars in optimized TSHB tests were compared with instability strains of thermoviscoplastic materials in simple tension given by Batra recently, and were also compared with computed instability strains based on the load-average strain of pure copper bars using adjusted thermoviscoplastic models.5) The recorded and recovered localized necking of pure copper bars in optimized TSHB tests and in HSTF with fixtures tests, respectively, were compared with the results computed with the micro-mechanical data based on static tension given by Ragab and the adjusted thermoviscoplastic models.