Page 1 of 6 The 7 th International Conference on FRP Composites in Civil Engineering International Institute for FRP in Construction CORELESS WINDING – A NOVEL FABRICATION APPROACH FOR FRP BASED COMPONENTS IN BUILDING CONSTRUCTION Riccardo LA MAGNA Dipl.-Ing., Institute of Building Structures and Structural Design (ITKE) – University of Stuttgart, Germany r.lamagna@itke.uni-stuttgart.de Frédéric WAIMER Dipl.-Ing., Institute of Building Structures and Structural Design (ITKE) – University of Stuttgart, Germany f.waimer@itke.uni-stuttgart.de Jan KNIPPERS Prof. Dr.-Ing., Institute of Building Structures and Structural Design (ITKE) – University of Stuttgart, Germany j.knippers@itke.uni-stuttgart.de ABSTRACT: In the current paper the authors present two case studies which expose innovative use of FRPs in engineering and architecture. A particular focus is set on the development of the coreless fabrication process specifically devised for the projects. The coreless technique developed as part of the research, offers an alternative to classical filament winding by replacing the positive mould with a linear steel frame, which provides the armature onto which the resin-soaked fibres are tensioned. Along with the planning of this alternative winding technique, specific computational tools had to be developed to accurately simulate the fabrication process and the mechanical response of the final structure. The coreless winding technique was implemented in the production of a full-scale prototype, an entirely carbon and glass fibre based monocoque shell. The second case study demonstrates the use of FRP based components for the production of a large scale structure. The coreless winding technique is adapted to the production of small size elements, which later serve as basic components for the assembly of a modular and double layer structure, allowing a larger span and the optimal transfer of global bending moments. The requirement of fabrication flexibility is resolved by adopting a specific robotic fabrication setup and an adaptive winding frame. 1. Introduction Filament winding represents a fast and economic fabrication method for fibre reinforced components (Bader, 2002). Particularly in the case of serial elements with repetitive and regular geometry, very cost- effective results can be achieved. Moreover, large components are easy to manufacture and a high fibre to volume ratio can be achieved, providing high stiffness and strength. Typical filament winding techniques involve the production of a positive mould onto which the fibres are later laid upon (Knippers et al., 2010). The mould ensures that the fibres are kept in place and do not slip into unwanted configurations while the polymer matrix is still in the process of drying out. Due to geometric constraints, the production of custom components is mainly limited to surfaces of positive Gaussian curvature (synclastic) such as pipes, vessels or aircraft fuselages. Besides, extra amount of work is required in the preparation of the mould, often a milled foam core, with the obvious waste of material that this process entails. For the production of surfaces of negative Gaussian curvature (anticlastic), automated tape and fibre placement methods may be employed. By using a composite lay-up end-effector typically installed on a robotic industrial arm, the tape is laid on the surface of the mould in direct contact. Although the design freedom is greater in this case, tape laying methods still suffer from the necessity of producing a positive core in advance, which also has strong influences on the size of the feasible components due to obvious logistic issues. To overcome these major drawbacks, a Coreless Winding process was developed for the production of a large scale prototype meant to test the potential and advantages of this innovative approach. This approach represents a novelty in the production of double-curved surfaces by winding. So far, the only method not requiring a winding core only allowed the manufacturing of pipes (Innovation Report, 2011). The alternative winding technique was mainly conceived to avoid the production of a large positive core, and was later implemented in the construction of a full-scale prototype (Fig. 1). In recent developments,