Ring Winding Technology: Increased Process Efficiency and Effects on the Mechanical Properties of Ring Specimens

For automotive applications high pressure storage of compressed hydrogen (CH2) becomes more and more important especially regarding the future sustainable mobility based on renewable energy. The filament winding technology is highly industrialized today to meet the requirements for a high-quantity production of lightweight fiber reinforced pressure vessels used for hydrogen-powered cars using fuel cells or combustion engines. However, the main disadvantage of the conventional wet winding process is the low lay-down rate. A decrease of the cycle time to increase the production rate can be realized by the simultaneous feed of a large number of rovings circumferentially arranged around the mandrel. A team of engineers at the Institut fuer Verbundwerkstoffe (Institute for Composite Materials) now further developed the ring winding technology to manufacture pressure tanks with a diameter up to 500 mm (20 inch) with fully wrapped dome sections. This large ring winding head with 12 radial movable arms and multiple payout eyes allows an accordingly higher material output and reduces the cycle time significantly. The profitability analysis considering ring winding head configurations with different number of feed-eyes show the optimization potential regarding the reduction of the production costs of FRP pressure cylinders. A critical review regarding reachable process efficiency is also given in this paper. A modified “tube siphon impregnation unit” is the most important component of the ring winding head due to its compact and modular design. This clean impregnation of 48 carbon fiber rovings near the winder minimizes possible resin leakages. In comparison to a conventional resin bath the amount of hazardous waste, for example contaminated acetone, can be reduced. FRP laminates (fiber reinforced plastic) with a reduced number of crossing points and less ondulation of fiber bundles result higher load bearing capacity and increased mechanical properties. Regarding the degree of interweaving the multi feed-eye configuration of a ring winding head makes it more challenging to define an optimized winding pattern with the given winding angle. The split disk test method was used for comparative investigations regarding the influence of undulations on the material properties of filament wound laminates.Copyright © 2011 by ASME