Instability and ductile failure of thin cylindrical tubes under internal pressure impact

The finite strain behaviour of a thin cylindrical specimen under hydrostatic pressure loading is studied numerically considering plane-strain deformations in the cross-sectional plane. The numerical results in the finite-strain range are generated by a finite element program developed for the problem analyzed. The strain-rate effects are taken into account by an elastic–viscoplastic material model. Only thin shells are considered in accordance with the membrane theory formulation employed. Dynamic instability with respect to time as well as deformation instability as strain localization are investigated. New results regarding the experimentally observed multiple neck formation phenomenon are presented. The onset of the instability as a weak discontinuity is discussed from the examination of the computed responses.