DYNAMIC ANALYSIS OF NECKING PHENOMENA

A new approach, based on the phenomena of stress wave propagation, is presented to analyse necking in the uniaxial tension test. The initiation of necking has been associated in this analysis with a stage, wherein the stress level at any section of the specimen acquires an instability stress value, and the stress wave velocity becomes zero at the section concerned. A method to compute the gradual development of the neck as a function of time with the aid of successive strain hardening curves has been developed. Experimental profiles were obtained by testing specimens of aluminium, copper, brass and low carbon steel under tension at two different velocities-one being hundred times that of the other-and unloading them after reaching different stages of necking. These compare well with theoretically obtained profiles. © 1979.