The goal of the project is the development and manufacturing of rCF staple fiber based organo sheets and the creation of an associated FE-model for the simulation of the thermoforming process of this material.
In the field of fiber-reinforced thermoplastics, prepreg materials, or so-called organo sheets, have been developed to allow the thermoforming of parts within very short cycle times. These semi-finished materials also show several other advantages, for example good storability, easy handling and in the case of wovens / non-crimp fabrics, excellent mechanical properties due to their continuous reinforcement. However, in contrast to these advantages, organo sheets unfortunately still have several major flaws: Namely restricted drapability and – in particular when using carbon fibers as reinforcement – relatively high costs. The project InTeKS addresses these disadvantages with the development of staple fiber yarns made of recycled carbon fibers (rCF). This structure allows the single fibers to slide past one another during thermoforming and therefore provides plastic formability in the fiber direction as a novel additional feature. Furthermore, the use of recycled carbon fibers reduces material costs. The responsibility of IVW in the project was the production of the organo sheets, the investigation of the thermoforming process and the development of a material simulation. For this, the FEM software LS-DYNA® was used to model organo sheets by means of a modular principle consisting of beam and shell elements. The results of the simulation provide information about the fiber orientation and distribution, temperature distribution, as well as the prediction of defects such as wrinkling, delamination or tearing of the preform sheet. In addition, important information about the plastic deformation of the material in the fiber direction along with local thinning based on volume constancy can be simulated for the material.