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Fiebig, Christian; Koch, Michael
Lightweight hybrid composites of CFRP and aluminum foam. - In: Materials science forum, ISSN 1662-9752, Bd. 825/826 (2015), S. 482-489

http://dx.doi.org/10.4028/www.scientific.net/MSF.825-826.482
Hartmann, Robert; Koch, Michael
Production of 3D parts from wood chips in a closed mold process. - In: Materials science forum, ISSN 1662-9752, Bd. 825/826 (2015), S. 1027-1032

http://dx.doi.org/10.4028/www.scientific.net/MSF.825-826.1027
Woyan, Felix;
Design trifft Funktion : Bericht zur Tagung "Folien + Fahrzeug 2015". - In: Kunststoffe, ISSN 0023-5563, Bd. 105 (2015), 5, S. 16-18

Düngen, Matthias; Koch, Michael;
Energy efficiency in injection molding. - In: Regional Conference Polymer Processing Society, Graz 2015, (2015), S. 63

Caba, Stefan; Koch, Michael;
Porenfreie Bauteile : Verringerung des Fehlstellengehalts und Prozessbeschleunigung im RTM-Prozess. - In: Lightweight design, ISSN 2192-8738, Bd. 8 (2015), 4, S. 56-61

Das Resin Transfer Molding Verfahren (RTM) zur Herstellung von Leichtbauteilen aus faserverstärktem Kunststoff wird vermehrt in Serienprozessen eingesetzt. Dabei ist stets ein Kompromiss zwischen kurzer Zykluszeit und hoher Bauteilqualität zu suchen. An der TU Ilmenau wurde die Fehlstellenentstehung während des Injektionsvorgangs genauer analysiert und eine veränderte Injektionsstrategie entwickelt. Die Analyse zeigt, dass bei geeigneten Prozessparametern die Herstellung fehlstellenfreier Bauteile möglich ist. Erzielbare Zykluszeiten erleichtern die Produktion in Großserienprozessen.



https://doi.org/10.1007/s35725-015-0032-2
Bruchmüller, Matthias; Koch, Michael
Simulierend modifizieren : geometrische Gestaltung von Reibflächen auf Sand. - In: Plastverarbeiter, ISSN 0032-1338, Bd. 66 (2015), 7, S. 54-55

Caba, Stefan; Koch, Michael
Analysis of the resin transfer molding (RTM) process for FRP and its process simulation fundamentals. - In: AIP conference proceedings, ISSN 1551-7616, Bd. 1664 (2015), 060010, insges. 5 S.

FRP technologies enable the production of lightweight components. The RTM technique is attractive to obtain vehicle parts with little post-processing in industrial scales. The closed mold process provides a desired freedom in part-design combined with high and reproducible production rates compared to other FRP processes. However, the shorter the mold-closed time the higher the risk to run into quality consistency issues resulting from air entrapments or voids due to degassing. This is a major obstacle to FRP processes in general. Other effects on fiber volume content and surface quality can be detected. These factors can be influenced by the choice of process parameters, thus flow pattern determining capillary forces, resin reaction velocity, reaction and mold temperature and others which can be specifically addressed by the change of simple process parameters. The dominant parameters on capillary forces are identified. Investigations were carried out to reduce mold-closed time to less than 5 minutes with reproducible high quality components with a minimum of voids for a serial production process. The essential process factors of the RTM process are identified and mathematically modeled. In particular, well known effects are comprehended in a quantitative approach that permits to specifically set up an industrial process and optimize achievable quality attributes. The void content in a FRP component is critical to mechanical performance and visual acceptance. The developed and presented process understanding allows to quantitatively predetermine achievable part performance at minimum cycle times. The process trials were conducted using a DOE-approach under consideration of material and process parameters for simple 2D parts. A visualization of the flow pattern in the cavity is presented and compared to the new approach of calculating the flow front development. The analysis shows the impact of principle process parameters on the achievable part quality.



http://dx.doi.org/10.1063/1.4918428
Koch, Michael;
Service performance - key measure for equipment sourcing. - In: PET planet insider, ISSN 1438-9452, Bd. 15 (2014), 10, S. 38-40

Hartmann, Robert; Koch, Michael
CFRP and aluminum foam hybrid composites. - In: Shaping the future by engineering, (2014), insges. 9 S.

One way to minimize the energy consumption of production processes is to reduce moving masses in machinery. This reduction of mass can be carried out through the exchange of solid material, like steel or aluminum, with hybrid materials. These hybrid materials combine application-oriented different type of materials and their properties. This paper deals with the RTM manufacturing process and FEM simulation of such a hybrid material. By using the sandwich design method two tensile-stiff carbon fiber reinforced plastic (CFRP) layers are connected to a low-density aluminum foam (AF) core in order to produce hereafter parts with high weight-specific bending stiffness. At the beginning of this paper an analytical calculation method on the basis of the beam theory is developed, which allows an estimation of the achievable mechanical properties of the composite. The bending stiffness of such a composite is mainly determined by the outer layer modulus and the gravity axis distance of the outer layers. These findings are incorporated into the development of a FEM model, which allows the simulation of various load cases with selectable composite structure. The challenge in developing this model is the implementation of the material-specific peculiarities. These include the anisotropy of the CFRP layers and the core structure of the AF. An experimental plan is developed by using the DoE method. It allows the determination of the RTM process parameters, which will lead to components with the highest weight-specific bending stiffness. On this account preliminary tests are carried out to identify the usable range of injection pressure, mold temperature and compression pressure of the press. This paper can demonstrate, that the production of CFRP/ AF hybrid material by means of the RTM process is feasible. The first manufactured specimens exhibit no displacement of the fibers and almost no air inclusions. The simulation of CFRP/ AF hybrid material could be implemented. The anisotropy of the CFRP layers can be simulated with the ANSYS fiber fracture software ACP. The structure of the AS core can be mapped with great computational effort. The next step is the execution of the developed experimental plan with an especially designed RTM mold for sandwich composites.



http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2014iwk-100:6