Lightweight Garage #17 CFRP-Components of the VW XL1 (2013)
March 24, 2022
by Bartosz Popiela
VW started working on the one-liter car concept back in 2002. In 2014, the production of the 200 units of the XL1 had begun. According to the manufacturer, fuel consumption is less than 1 liter per 100 km, to which the low overall mass of the model contributes significantly.
©Thomas Wolf, www.foto-tw.de, Volkswagen XL1, CC BY-SA 3.0 DE
The use of lightweight materials is crucial here: 21.3 percent of the vehicle's mass is carbon fiber-reinforced plastic (CFRP) parts, and a further 22.5 percent is lightweight metals. The lightweight solutions in the body and monocoque areas are of particular interest.
The CFRP components of the monocoque and the body, which are mainly manufactured using the Resin Transfer Moulding process (RTM), enable a significant reduction in weight. The body of the XL1 weighs only 230kg. At the same time, the low weight has no negative effect on the mechanical properties of the structure. The reason for this is the very good specific mechanical properties of CFRP. By using fibre-reinforced-plastics, direction-dependent mechanical properties of the structure can be achieved, resulting in extensive lightweight optimisation.
Rainerhaufe, Karosserie XL1 Gläserne Manufaktur, CC BY-SA 4.0
In the RTM process, dry semi-finished fibre products are placed in a two-part mould, which is then closed. In the next step, the reaction resin is injected under pressure. After complete impregnation, the component is cured under holding pressure. In the RTM process, comparatively high fibre volume ratios of over 50% can be achieved, which has a positive effect on the mechanical properties of the finished components. In addition, the process can be easily automated, which ensures high reproducibility.
The specific weight of the XL1's carbon fiber-reinforced outer skin is only 20 percent of a comparable steel outer skin. At the same time, the low weight has no negative effect on the mechanical properties of the structure.
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