Strength and weight equivalent substitution of large sandwich panels by monolithic CFRP structures

Description

A general trend in the aircraft industry is to replace sandwich structures made from fiber-polymer-composites and low-density honeycomb cores by monolithic structures entirely made from fiber-polymer-composites. The fields of applications addressed here are primary and secondary control surfaces of civil aircraft wings and stabilizers. However, they can be directly extended to other applications. The main motivation for such a substitution is to reduce manufacturing efforts. For honeycomb sandwich designs mainly resin pre-impregnated fiber semi-finished products are applied and often the structures are built and cured in an autoclave in one or several steps. This is cost intensive. Thus, resin infusion technology is an attractive alternative. Dry fibers are saturated with resin during the curing process by applying vacuum. Here, just an oven is required. Another reason is that sandwich structures used on aircraft are exposed to large varying environmental conditions. Condensation and absorption of water can cause an increase in the total mass and once the water is frozen, serious damages may occur. Other advantages include ease in detection of structural damages and manufacturing defects and reduction in repair efforts. Control surface structures are loaded by pressure distributions over their surfaces. The sandwich design is optimal to withstand bending moments, shear forces and torsional moments. The challenge is to keep the mass, when the design is changed to monolithic. This contribution presents two design alternatives, one developed on top of the other, which allow the manufacturing of monolithic highly integrated laminated structures within one layup and curing step. Additionally, aerodynamic properties are guaranteed on the top and the bottom of the control surface. A reference structure is derived from a state-of-the-art spoiler, which is equipped with a honeycomb core. This structure is then compared with the alternative design proposed

Period	08 Jun 2016
Event title	VII European Congress on Computational Methods in Applied Sciences and Engineering
Event type	Conference
Location	GreeceShow on map