Structural automotive functions, like floor pan, could potentially be made with composite materials. However, some of these parts include hollow areas like cross beams. Manufacturing the complete composite part including the cavity could be a cost effective solution if the selected technology allows the fabrication of this part in one step. The Bladder Resin Transfer Molding process is one of the most convenient technology for manufacturing this composite part with complex shape, hollow areas and high fiber content, with a reduced number of tools and steps. Bladder RTM technology has been extensively used for manufacturing hollow parts. The inflation bladder pressure is directly related to the pressure inside the mold. However, this approach is not valid when the hollow part is one area of a bigger monolithic part, and when the resin injection pressure is not controlled. In that case, the inflation pressure of the bladder cannot be only correlated with the local pressure inside the mold. An injection method including bladder molding technology has been developed to manufacture a complex part having an hollowed cross beam, which represents approximately a fourth of the automotive floor pan. The work carried out addresses mainly the adaptation of the inflation bladder pressure with respect to the local injection resin pressure and compression properties of the fabric. An analytical method has been proposed to predict the local resin pressure variations when the part is small and when geometry of the hollow core is not too complicated. For more complicated geometries or to improve the model accuracy, it will be necessary to develop and use simulation tools to predict the resin pressure and the flow front shape and advancement taking into account the bladder and fabrics deformation. The RTM bladder molding technology could be implemented as a low volume production process for automotive parts. To get a reliable process, it is recommended to develop a 'smart' process able to adapt on-line during the mold filling the inflation pressure with respect to the continuously evolving pressure.
Bladder molding technology for manufacturing structural automotive parts
Bladder-Harzspritzpressen für die Fertigung von Kraftfahrzeugbauteilen
2004
7 Seiten, 3 Bilder, 2 Tabellen, 5 Quellen
Aufsatz (Konferenz)
Englisch
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