Material Instabilities in the Experimental Study of the Plastic Compressibility of Some Important Metals

摘要

The hypothesis of plastic incompressibility, which is pivotal in the development of the classical theory of plasticity was tested by means of a series of simple tension tests on aluminum, copper and low carbon steel. The experimental measurements show conclusively that these metals are plastically compressible, the compressibility increasing with straining in the plastic region. A new phenomenon, termed lateral instability, was also observed, consisting in an abrupt plastic flow in the transverse direction either immediately preceding or immediately following yield in the longitudinal direction, during a simple tension test on low carbon steel. To a less pronounced extent such a phenomenon was also observed in the case of commercially pure aluminum. (AUTHOR)