Evolutionary fractal theory of erosion and experimental assessment on MIR space station

In this paper, we present a new approach to study erosion phenomena. It is substantially based on multi-scale and fractal concepts. The theory permits to predict the wear in terms of mass loss evolution for one-, two- and three-dimensional structures under erosive flows. In particular, a comparison with the results of an experimental investigation-only recently published-performed during 28 and 42 months of in-flight exposure for the MIR orbital space station, is presented. The experimental analysis gives the mass loss of polymer films, used as protection against erosion due to space debris impacts, as a function of in-flight exposure time, as well as their life-time predictions, crucial parameters for an optimal design of the protective films. The theoretical approach predicts a catastrophic damage evolution in terms of eroded mass as a function of the exposure time. This surprising time-effect is experimentally confirmed, showing that the trivial assumption of steady-state damage evolution is strongly non-conservative. (C) 2004 Elsevier B.V. All rights reserved.