Cornelia Sennewald

Woven Semi-finished Products and Weaving Techniques

This chapter introduces the structural description, weaving-technical manufacture and possibilities of woven fabric structure modifications for the development of practically suitable woven fabrics for application in lightweight construction. The basic structural set-up, methods for its description and the properties resulting from the structure of the woven fabrics will be clarified. An overview of basic methods of woven fabric manufacture and the corresponding weaving machines will demonstrate the diversity of technical solutions for a gentle and damage-free processing of special and high-performance fiber materials into a variety of woven structures. The focus of the chapter will be on an extensive introduction to woven structures and the respective structural modifications. This includes 2D structures as flat, grid, multiaxial, and polar woven fabrics, 3D structures as multilayered woven fabrics and spacer fabrics as well as shell-shaped 3D geometries. As early as during the production of the woven fabrics or the preforms, the inclusion of special fibers or external materials, such as electronic devices and inserts for mechanical connections, additional functions can be integrated.

Development of adaptive pleated woven fabrics with shape memory alloys

The growing demand for fiber-reinforced plastics for different high-tech lightweight applications requires their consistent and continuous development with a high functional density. The integration of actuator-like materials for developing adaptive reinforced fabrics can increase the market value of fiber-reinforced plastics. This paper reports on the development of adaptive pleated woven fabrics based on shape memory alloys using weaving technology. For the development of these fabrics, a systematic weave pattern was generated. Adaptive pleated woven fabrics were manufactured on a rapier weaving machine with a jacquard unit. By varying the pleat thickness, pleat width and the spacing between two pleats, eight types of adaptive pleated woven fabrics were developed, and their weaving-technical implementation for the subsequent infusion was evaluated. The flexural modulus of infused adaptive pleated woven fabrics was characterized by bending. Experimental results showed that the spacing between two pleats predominantly influences the flexural modulus of impregnated adaptive pleated woven fabrics.

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.

Development of Woven Spacer Fabrics Based on Steel Wires and Carbon Rovings

Woven spacer fabrics are used as reinforcing materials for fiber-reinforced plastics. These fabrics consist of mostly pliable textile fibers, which still require defined rigidity for different crash applications. In this regard, multi-material woven spacer fabrics present a promising approach. This paper presents the development of multi-material woven spacer fabrics using steel wire and carbon rovings. For the development of such woven spacer fabrics, a systematic structure realization based on the weave pattern was performed. Selected structures were produced on a modified weaving machine.