New protection concepts for meteoroid / debris shields

Manned space missions demand advanced safety requirements concerning protection against space debris and meteoroid impacts which lead to heavy shielding structures. In order to decrease the weight of shield systems without compromising the protection performance, or in order to increase protection levels at constant weight, modern shield concepts have been evaluated by means of experimental and numerical impact simulations. New configurations have been compared with existing "Stuffed Whipple Shield" protection systems. Such systems consist of an Al-bumper and a so-called "stuffing layer" consisting of a combination of ceramic and aramid fabrics. Results are presented for Al-foam sandwich bumpers and bumpers of TiAl super alloys. A number of materials have been implemented as stuffing layers: Kevlar fabrics, Nextel fabrics combined with Kevlar fabrics, and Kevlar fabrics combined with polyurethane foam. Numerical simulations are carried out for the Al-foam shields. These calculations are conducted mesomechanically, i.e. the cell walls of the foam are modelled explicitly with a finite element mesh. The aim is to study the influence of the foam on the distribution of momentum of the debris cloud.