The dynamic indentation response of stainless steel sandwich panels with a corrugated core or a Y-frame core has been explored using the finite element method to gain insight into the potential of the cores to mitigate against collisions over a wide range of impact velocities pertinent to land and sea-borne vehicles. Back-supported sandwich panels were impacted on the front face by a flat-bottomed or a circular punch at constant velocity ranging from quasi-static loading to 100 m/s. At velocities below 10 m/s the forces on the front and back faces are equal but inertia stabilisation raises the peak load above its quasi-static value. This strength elevation is greater for the corrugated core than for the Y-frame core, and more pronounced for the flat-bottomed punch than for the circular punch. For velocities greater than 10 m/s, the indentation force applied to the front face exceeds the force transmitted to the back face due to plastic-shock effects. In this regime, the force transmitted to the back face by the Y-frame core is markedly less than for the corrugated core, and this brings a performance benefit to the Y-frame, i.e. it protects the underlying structure in the event of a collision.This research was carried out under the project number MC2.06261 in the framework of the Research Program of the Materials innovation institute M2i (www.m2i.nl). The authors are also grateful for the financial support of the Fonds Québécois de la Recherche sur la Nature et les Technologies (FQRNT).This is the accepted manuscript of a paper publishing in the International Journal of Mechanical Sciences (L St-Pierre, NA Fleck, VS Deshpande, International Journal of Mechanical Sciences 2015, 92, 279–289
