ETH Research Database

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1 ETH Research Database Project Summary Combined OOA prepreg/lcm process 1) Creation date of the summary: ) Record ID: ) Last update: ) Project status: Ongoing ( ) 5) Organizational unit: Departement Maschinenbau und Verfahrenstechnik, Institut für Mechanische Systeme (IMES), Ermanni, Paolo, LZ= ) Project leader(s): - Klunker, Florian, 7) ETH researcher(s): - Danzi, Mario, mdanzi@ethz.ch, Dep. Maschinenbau und Verfahrenstechnik, Inst. f. Design, Mat. und Fabrikation 8) External researcher(s): no entry 9) Funding source(s): - EU - Own resources of the professorship 10) Partner organizations: RUAG Schweiz AG, P.O. Box 301, 6032, Emmen, Switzerland 11) Short Summary: Combine the prepreg and the Liquid Composite Moulding (LCM) technologies in a single hybrid process would permit to expand the concept of integrated structure, being <page 1>

2 able to exploit the advantages of both techniques and reducing the manufacturing cycle time. 12) Keywords: Aerospace Engineering, Engineering Sciences 13) Project description: Framework: The research project is in the framework of the ŞClean SkyŤ Joint Technology Initiative. The Clean-Sky Project is one of the largest and most ambitious aeronautical research program ever launched in Europe. It involves the leading aerospace industries (EADS, Airbus, Eurocopter, Dassault, Saab and many others) with the mission to develop breakthrough technologies to increase the environmental performance of airplanes and air transport. The Swiss cluster, led by RUAG, focus on green design and new manufacturing routes for low cost and energy consumption processes. The Centre of Structure Technologies of the ETH Zürich is focusing its activities on green composite design and manufacturing routes for a more sustainable and efficient future. Motivation: Prepreg technology is based on pre-impregnated composite fibres. The fibre fabrics already contain an amount of non-cured matrix material that bonds them together. The prepreg technology presents a high degree of process reliability and a final quality of the components. Laminates produced with prepreg material can reach, with respect to other manufacturing methods, excellent mechanical strength properties and high fibre volume contents. Moreover, the properties of the resin system can be tuned with additives, in order to obtain special burning behavior or higher toughness. For all these reasons, the prepreg material is mostly used in advanced applications, where excellent properties of the structure are required, like for example in aeronautics and space industry. A disadvantage of the prepreg technology is the low drapeability of the pre-impregnated fabrics, which makes it difficult to manufacture parts with complex shapes. The prepreg is consequently more suitable for the manufacture of large and flat components, where, for example, automated tape placement methods can be used. However, the high costs of the prepreg material and the high amount of energy needed for the manufacturing of these components, especially in autoclave processing, make the industry look for alternative production methods. The new trend is now Şout-of-autoclaveŤ (OOA) prepreg systems, which permit the manufacturing of high quality parts in oven and Şvacuum bag onlyť (VBO) systems. They are based on resin system with lower viscosity, which permits a better extraction of entrapped air and moisture during the processing. The Liquid Composite Moulding (LCM) technology, compared to other technologies, allows free combination of fibre and matrix as well as a high flexibility in the fabrication process. Even very complex geometries can be reproduced thanks to the excellent drapeability of the materials. The injection resin requires low viscosity in order to fully impregnate the dry fabric in a reasonable time. Low viscosity resin systems are more brittle compared to prepreg resin systems, which leads to lower mechanical strength of the LCM laminate. A hybrid process that combines these two technologies would ideally allow to manufacture high integrated parts by using the advantages of both processes and get high quality and high complexity parts. It would revolutionize the out-of-autoclave production of parts and reduces by noticeably amount <page 2>

3 the processing times of complex structures. This kind of process could be particularly suitable for the manufacturing of airplane fuselage or airplane wings structures. Research approach: The research approach is considering a number of challenging topics including: Ţ Material choice: The resin systems used should be the compatible. The co-curing process should have no influence on the mechanical properties of the interfaces. Ţ Process feasibility: Perform mechanical test on hybrid laminate to show if hybrid processes are suitable for the production of high quality laminate. Ţ Process mechanism investigation: Identify and investigate the most important issues and mechanisms involved in hybrid processes. Mechanisms, like the bleeding of the prepreg resin into the dry fabric, have a remarkable influence on the final mechanical properties of hybrid laminate. Ţ Investigation of process robustness: Investigate the process robustness with respect to real manufacturing applications, like in the case of large and complex structures. Ţ Process sensitivity analysis: Acquire information about the influences of the different process parameters on the properties of the final laminate. Ţ Process parameter optimization: Combine the knowledge acquired with simulations and the results from mechanical test to optimize the process parameter, which allow to fully exploit the advantages of the hybrid process. 14) Popular description: no entry 15) Graphics: Combined OOA prepreg/rtm process demonstrator <page 3>

4 IMES, ETH Visualization of the bleeding of the prepreg resin IMES, ETH 16) Publications: no entry <page 4>

5 17) Links to important web pages: <page 5>