Neck propagation

Propagation of a neck along the length of a tensile specimen as occurs in certain polymeric materials and in a few metals is studied. Two material models are considered: a nonlinear elastic solid, and an inelastic flow theory solid with both rate-dependent and rate-independent behaviors. For the elastic solid the states ahead and behind the neck transition can be obtained fairly simply from just the jump conditions governing continuity of mass, momentum and energy. For the inelastic solid a full three-dimensional analysis must be performed to obtain the same information, and an analysis of axisymmetric neck propagation is carried out.