Ordered and Highly Scalable Granular Media for Shock Mitigation

Report No. ARL-TR-3612
Authors: Robert Doney and Surajit Sen*
Date/Pages: September 2005; 68 pages
Note: *State University of New York, Buffalo, NY
Abstract: We provide an update to our current efforts in studying shock mitigation using one-dimensional arrays of adjacent metal spheres that may progressively shrink in size. These tapered chains are characterized by the number of spheres, N, the amount of tapering, q, and restitutive losses, ω. Spheres are assumed to interact via the nonlinear Hertz potential, V α δ5/2, where δ is the amount of overlap of adjacent grains and the constant of proportionality varies with the material. To gauge the ability of such chains to absorb transient pulses, we look at the normalized kinetic energy, KEN, as a function of N, q, ω. A hard-sphere approximation and numerical analysis is therefore performed for 3 ≤ N ≤ 20 and 0 ≤ q, ω ≤ 0.1 for two tapered chain architectures. Intended experimental studies are outlined as those that have already been performed and focus on solitary wave propagation in monodisperse (q = 0) chains. Results are quite encouraging and independent of system size; consequently, we propose a tapered chain armor panel design consisting of many tapered chains working in tandem. The specific and gravimmetric absorbed energies are calculated for an example prototype. Intended work and further discussion are provided in the conclusion.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2005