Wave propagation and strain localization in dynamically loaded specimen

Abstract
The aim of the presentation is focused on two aspects which are the influance of the waves propagation in specimens on the choise of places of strain localization and the discussion of numerical models that serve the recognition of this phenomenon. There are some experimental tests which are under consideration (thin plate, axisymmetric bar, 3-D specimen) which are numericaly studied. The experiments are made in the Hopkinson tube with the typical velocity of deformations of order 10⁴ s^-1 so the processes could be treated as adiabatic. For ductile materials under such conditions to avoid the mathematical consequences due to thermal softening (ill-posedness) the viscoplastic constitutive description is used. In numerical simulations we have shown the well-posedness of the solution of governing equations by showing the insensitivity of the results to spatial discretization. The set of numerical examples proofs that it is possible to estimate the places of strain localization by observing the velocities of particles. Intensive plastic zones appear in the places where the local velocities are close to zero. In the formulation we have accepted the constitutive viscoplastic model, finite deformations and the evolution of porosity. The computations were performed in the environment of ABAQUS finite element program.