Technology Development for Direct Weaving of Complex 3D Nodal Structures

Lightweight structures constitute an eminently important solution to the conservation of limited resources of energy in aeronautics and vehicle engineering. The increasing necessity to implement lightweight construction concepts for framework structures due to their vast application makes requirement-adapted node structures attractive for fiber-reinforced plastic composites (FRPC) components. Although the use of FRPC for framework structures is well-established by now, the node structures are still mostly made from aluminum or titanium, which results in additional costs and limits the achievable mass reduction. Hence solutions for FRPC node structures have to be developed. The aim of this work is the development and implementation of a productive, automated manufacturing technology based on the weaving process for complex node structures based on carbon fiber for automotive and aeronautics applications. The development of the woven concept for the realization of node structures is based on the fragmentation of the individual sub-elements. The sub-elements are virtually unwound into the layer and positioned one above the other. The warp threads are floated in the areas where the individual levels do not touch. The node structures are produced on the conventional weaving loom by flattening and weaving them as multi-surface woven fabrics in one piece. The tube profiles are produced seamlessly, and the connection points between the tubes are jointless. By pulling the warp yarns in one branch through the structure, the gap is closed and the 3D geometry is formed. The defined pulling of the warp yarns is the main component of this publication. This new technology allows for the weaving of complex, integrated node structures with multi-directional spatial branching without subsequent assembly requirements. These newly developed node structures show great potential for lightweight construction applications. They can be manufactured with good reproducibility and a high degree of automation. The results of this work indicate an enormous potential of the weaving technique for the cost effective manufacture of integrally designed, woven 3D semi-finished products for FRPC. Typical applications for node structures include stringers and floor frames in airplanes, machine components, car frame parts, such as A-, B-, or C-pillars.