Development and validation of a virtual process chain for composite structural components considering imperfections with application to a rotor blade component

• Applicants: Professor Dr.-Ing. Axel Herrmann; Dr.-Ing. Jan-Hendrik Ohlendorf; Professor Dr.-Ing. Raimund Rolfes; Professor Dr.-Ing. Klaus-Dieter Thoben
• Subject Area: Lightweight Construction, Textile Technology ; Materials in Sintering Processes and Generative Manufacturing Processes
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 329147126

This project aims at reducing the flaws due to manufacturing in composite structural components with the help of simulating the full process chain (manufacturing simulation and structural analysis) and at making the process deviations smaller through a more precise knowledge of the underlying process relations. There is a need for research at this moment since the current knowledge relates to the individual process steps only and because a process simulation through the whole process chain is not available as yet. In this project, establishing a virtual process chain for the manufacturing of composite structural components for a wind turbine rotor blade is defined as a concrete objective. In order to be able to predict the mechanical strength of the structural component, the manufacturing process is represented by a draping and handling simulation and an infusion simulation, and the curing process is included in the structural analysis in an appropriate way. The resulting process parameters related to the actual position of the rovings and the resin saturation can be used in the final step of strength analysis of the composite component manufactured. The influence of flaws due to the manufacturing process on the structural behavior is quantified with appropriate Finite Element models in systematic, numerical investigations. Probabilistic analyses in all phases of the process simulation, in which the statistical distribution of imperfections are considered, provide the corresponding scatter of the structural properties. The analysis of the complete process chain - manufacturing simulation and structural analysis - makes it possible to simulate the influence of production related imperfections on the structural behavior and to specify flaw tolerances connected with the manufacturing process. This is achieved in particular through the new approach presented, in which the most relevant imperfections (e.g. geometrical deviations or scatter of material properties) are included at different modeling levels. For this aim, the composite material is analyzed in detail at three levels, the micro-scale (single fiber), the meso-scale (roving) and the macro-scale (roving-composite). On the basis of the results of the simulation of the complete process chain, criteria and design rules for flaw tolerances - flaws which in the manufacturing process of a typical, relevant structural component can be considered as acceptable - can be established, and thereby the product scrap rate can be reduced and certification processes can be facilitated.

• DFG Programme: Research Grants