EXPERIMENTS ON ANNEALED ALUMINUM,
PRINCETON UNIV N J DEPT OF AEROSPACE AND MECHANICAL SCIENCES
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This investigation is a study of the quasi-static stress-strain relation for the case of biaxial stress in annealed commercially pure aluminum, and its implications with respect to the speed of propagation of disturbances caused by incremental stresses. Tubes of 1100 aluminum are subjected to combined tension and torsion loads. A very slow loading technique using very small load increments is employed. At the conclusion of static testing, specimens are subjected to torsional impulsive loading superimposed upon a biaxial prestress. The main points of this work are all existing commonly used theories of plasticity in solid mechanics cannot possibly apply to mechanically unstable materials and applying shock wave and Karman-Taylor theory to the experimentally determined quasi-static stress-strain curve for annealed 1100 aluminum accounts for all experimentally observed wave speeds for both fast and slow loading techniques without including strain rate effects.