Experimental research on fiber compaction of L-shaped stiffeners in stiffened skins by autoclave process

L-shaped stiffeners were fabricated by integral co-bonding technique in the autoclave. This study focused on investigating the influence of tool assembly, filler, curvature radius and bleeding process on the fiber compaction and manufacturing defects of L-shaped stiffeners, with analyzing the formation mechanism of these defects. The results indicated that non-uniform thickness, bridging and rich resin were the main defects of L-shaped stiffeners. The fiber compaction was improved significantly on the condition that the pressure in corner section was increased by applying flexible tools and rolling unidirectional prepregs as fillers into the stiffener core, and that the corner effect was remarkably caused a decrease by increasing curvature radius and applying pre-bleeding process. All these results are the vital importance for declaring the formation mechanism of defects and enhancing integral manufacturing quality of composite stiffened skins.