Impact of shipbuilding steel plates with an initial tensile stress

Abstract
The present investigation is concerned with the impact of thin steel plates used in shipbuilding. The problem is studied numerically with the commercial code LS-DYNA and experimentally with an apparatus propelling a 200g projectile up to 30m/s with a crossbow. The clamped sample of sheet metal is rectangular (250 mm wide; 20 mm width and 4 mm thick), in common shipbuilding material with a 360MPa elastic limit. Impact takes place at the center of the sample. Moreover, an initial tensile stress can be applied to the plate, up to 300 MPa. The aim of this study is first to illustrate the influences of the boundary conditions and the initial tensile stress value on the deflection of the central point of the plate. The second part is concerned with wave propagation. The objective is to explain analytically the dispersive form of the measured strains at different locations and to establish the relationship between the flexural waves and the observed losses of contact.