Numerical and Experimental Evaluation of the Hypervelocity Impact Performance of an Aluminum Foam and Uhmwpe Stuffed Sandwich Panel

Abstract

As the instances of Orbital Debris (OD) in Low Earth Orbit (LEO) continues to increase, so does their risk of impacting orbiting platforms. Therefore, designers of these platforms need more diverse tools to manage the risk posed by OD. Aluminum foam and Ultrahigh Molecular Weight Polyethylene (UHMWPE) woven composite, trademarked as Spectra and Dyneema, are potential shielding materials with promise to increase orbiting platforms’ protection against foreign object impact damage. This may be achieved without significant weight penalty when inserted between the two spaced Aluminum plates that compose a Whipple Shield, the historical means of OD protection. A numerical model of a 40 ppi 7.2% relative density Aluminum Foam Sandwich Panel (AFSP) has been built using LS-DYNA via Voronoi tessellation, with impact analysis conducted using Smoothed Particle Hydrodynamics (SPH) FEA. This model was validated against published Aluminum foam hypervelocity impact (HVI) data. Using the validated model, a layer of Dyneema stuffing was (will be) added to the shielding structure using a proprietary polyethylene material model, and HVI simulations were (will be) conducted. The hypervelocity damage resistance was (will be) assessed via a series of HVI tests against targets consisting of Aluminum 6061-T6 7.2% relative density AFSPs, stuffed with Dyneema HB210. All experimental HVI tests were (will be) carried out with a Light Gas Gun at the Fraunhofer Ernst-Mach-Institute in Freiburg, Germany. The results of these tests will also be compared against published HVI data on CFRP honeycomb sandwich panels (HCSPs) and Kevlar 258HPP stuffed AFSPs, which are currently examples of sophisticated shields used in uncrewed and crewed orbiting platforms, respectively. All tested samples have areal densities identical to the CFRP HCSPs and Kevlar 258HPP AFSPs from published HVI impact data, 0.59g/cm2 and 1.12g/cm2, respectively, so that relative performance may be determined by comparison on the same ballistic limit curves. The performance characteristics of the Dyneema-stuffed AFSPs relative to the test data on the flown samples and the numerical simulations will be presented, providing insights for the next generation of UHMWPE-based composites for HVI shielding applications, and validating the numerical model for further work.