Title: J046032 Preparation of high surface accuracy CFRP skin/form core sandwich panels and evaluation of their surface shape
Abstract: As a new material suitable for the primary mirror of space telescopes, we focused on foam core CFRP sandwich panels which satisfy lower surface roughness than the conventional honeycomb core sandwich panels. However, large deformations appeared at edge of the ROHACELL (polymethacrylimide based foam) core sandwich panels surface. In order to improve the surface accuracy, we analytically investigated the influence of core thickness and of using the GRAFOAM core (carbon-based foam) having a low coefficient of thermal expansion. Then, ROHACELL core sandwich panels with two different core thickness and GRAFOAM core sandwich panels were manufactured and the surface accuracy of those panels were experimentally measured. Analytical and experimental results showed that edge effect decreased on ROHACELL core sandwich panels with thinner core thickness, and that the edge effect was suppressed by using the GRAFOAM core. In addition, because of lower CME(coefficient of moisture expansion), deformation due to moisture absorption is small.