Design strategies and production processes of strength-optimised lightweight structures made of composites with variableaxial fibre architecture (OptiTex)

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Textile-reinforced plastics, a still young family of materials, promise a substantially high potential for lightweight solutions. Here, the textile fibre layout can be adapted for complex locally changing force flow orientations similarly to constructions in nature. The matrix material, which is also specifically chosen for the load conditions, serves mainly the protection and stabilisation of the textile reinforcement as well as the generation of a uniform force distribution. For a variety of textile reinforced composite structures the strength requirements dominate the design process, which, however, is much more demanding than stiffness driven designing. To fully exploit the high strength potential of the new textile reinforced material group adequate textile and plastic technologies have to be provided as well as material-oriented analysis and optimisation strategies with physically based failure criteria considering the limits of the specific manufacturing parameters of the textile process. For this purpose, a very close link between the process steps material construction, calculation and manufacturing is absolutely necessary in order to develop strength-optimised composites with variableaxial textile reinforcement. Thus, within this collaborative research project, an intensive interdisciplinary cooperation between the disciplines modelling, simulation and optimisation, on the one hand, as well as manufacturing of textile preforms with a given fibre layout and its consolidation with high fibre volume contents on the other hand, is intended. Hence, the present planned collaborative project differs clearly from research projects in the field of bionics, which mainly deals with stiffness optimisation.Within the proposed research project, both thin-walled and thick-walled composite structures manufactured by the technologies Tailored Fibre Placement (TFP) and multi-axial non-crimp fabric with partial adjustable warp fibre placement (MAG-KV) will be investigated. Both of them allow a variableaxial fibre reinforcement layout and qualify for large-scale production. The first period of the research project comprises designing and validation of specific thin-walled demonstrators to achieve the maximum strength limits using the developed process-oriented simulation and optimisation methods. In this context, aspects about textile-oriented designing of metallic bearing areas will be clarified too. Technology-based methods developed by investigating plane and spatially shaped thin-walled specimens will be experimentally validated by fracture tests with tension, bending and torsion loads. Based on this knowledge the demonstrator and design complexity will be increased by analyzing thick-walled composites within the second period of the research project.