Dynamic Necking of Rods at High Strain Rates

V. Jeanclaude , C. Fressengeas

The dynamic necking instability of a rod of a non-linear viscoplastic material as formed in shaped charges is investigated. A two-dimensional linear Lagrangian perturbation method leads to a single fourth order partial differential equation with time-dependent coefficients. The growth of disturbancies depends of the interplay between the stabilizing inertial and viscous effects, and the destabilizing geometrical softening of the rod. Inertia slows down the growth of long wavelengths, while viscosity damps preferentially the short wavelengths. A time-increasing critical wavelength of maximum perturbation growth is selected at each moment. The latter is characteristic of the length scale of a multiple necking phenornenom.

Domaines: Articles anciens

V. Jeanclaude, C. Fressengeas. Dynamic Necking of Rods at High Strain Rates. Journal de Physique IV Proceedings, 1997, 07 (C3), pp.C3-699-C3-704. ⟨10.1051/jp4:19973119⟩. ⟨jpa-00255404⟩