(4148)CORNER CONSOLIDATION IN VACUUM BAG ONLY PROCESSING OF OUT-OF-AUTOCLAVE COMPOSITE PREPREGS LAMINATES

摘要

Out-of-autoclave (OOA)prepreg systems are of great interest for the aerospace industry, with mechanical properties similar to that of autoclave-processed prepregs. The processing of flat or low curvature parts is generally not problematic with vacuum bag only OOA prepregs. On the other hand, the moulding of parts with sharp corners often leads to significant thickness variations and voids concentrated at the corners. In this paper, the mechanisms that govern the compaction of complex shape composite laminates using OOA prepregs are investigated. The goal of this research is to develop guidelines and tools for the adequate design and manufacturing of parts with sharp corners, using vacuum bag only processing methods. Thickness variation at the corner of L-shape laminates with various radii and flange thicknesses were characterized. The quality of the manufactured parts was analyzed in terms of thickness deviation in the corner region, and the results compared with previous work done on L-shape laminates. Laminate thickening was observed at the corner. Results show that thickness variation of OOA L-shape laminates depends on tool radius, laminate thickness and flange length. A modelling of the corner thickness deviation was proposed. It accounts for the main deformation mechanisms: local compaction pressure differential and interply friction. To quantify these effects, the bulk factor was characterized and the interply slip behaviour was measured using a specifically designed testing fixture. A general analytical corner compaction model was obtained, and results were compared with the above experimental data.