An active concept for limiting injuries caused by air blasts

We explore the feasibility of cellular materials concepts for passive and active mitigation of blast over-pressures. The passive approach requires a cellular medium that compresses at nominally constant stress and dissipates the kinetic energy acquired by an attached buffer plate. Provided the cellular material is not compressed beyond its densification strain, the transmitted pressure is approximately the dynamic crush strength of the medium. This can be set just below a damage threshold by appropriate selection of the cellular material, its topology and relative density. However, for many realistic blast scenarios, the thicknesses required to avoid excess densification are excessive. The alternative is a deployable, pre-compressed, cellular medium released just prior to the arrival of the blast-created impulse. This accelerates an attached buffer toward the blast and creates momentum opposing that acquired from the blast. Numerical simulations of the fully coupled fluid structure interaction in air show that momentum cancellation is feasible, enabling a protective structure having much smaller volume. (C) 2009 Published by Elsevier Ltd.