Essais d’impact et propriétés thermiques résiduelles sur composites silice/phénolique

Abstract

Silica/phenolic composites are used in atmospheric re-entry heat shield parts in spatial and strategic domains. For this application, the material is submitted to thermo-mechanical stresses that lead to delaminations. To reduce the effect of these delaminations, it was proposed to cut silica fabrics and to reassemble them like a patchwork. « Classical » (2D 0°/90° fabric stacks) and « patchwork » materials were impacted on an instrumented falling-weight tower (Instron). These tests were carried out at different energies to create different levels of damage. The damaged samples were analysed by X-Ray micro computed tomography to reveal in particular the delaminations morphologies. In parallel, initial and residual transverse thermal diffusivity measurements were realised on these samples for different damage states. These measurements permitted setting up correlations between loss of thermal diffusivity and material damage. Comparisons between results on « classical » and « patchwork » samples have highlighted differences in damaging modes and a limited interest of the patchwork solution.