EDAG Light Car Open Source
From EDAG: A special space frame structure covered with the type of lightweight plastic outer skin panels and already produced by EDAG as Class A-type "HT PU RIM components" for low-volume series, has been developed for the EDAG "Light Car - Open Source. With a minimum of capital expenditure and using polyurethane technology, it is possible to bring about weight-optimised exterior skin components that can be used economically in low-volume series, while providing a high degree of design freedom.
The Gaia battery with lithium iron phosphate cells has been integrated in the main floor of the platform, and is part of the load bearing structure. For the drive system, there are two wheel hub motors mounted in the rear axle, which provide a maximum speed of 140 km/h. By keeping themselves constantly geared to the potential of an electric drive system, EDAG engineers designing the package have achieved a wheelbase measuring 2.90 metres. This puts the interior dimensions of the EDAG "Light Car - Open Source" on a par with luxury class vehicles, while the exterior dimensions are those of a compact car (length: 4.1 m, width 1.75 m and height 1.5 m).
A combination of steel, aluminium and fibre composites was selected to construct the space frame structure. This guarantees not only adequate energy absorption by crash-relevant structure components, but also maximum stability at the lowest possible weight, and the best possible protection for passengers and the battery in the event of a collision. To this end, laser-welded and partially hardened sections made of extremely high performance steel were used in the floor, door sill, A-pillar and front end areas. Developed by our open source partner Linde + Wiemann, this process makes it possible with precise accuracy to increase the strength and expansion properties of the component in areas where particular demands are made on material strength. In this way, optimal solutions can be applied to vehicle and component characteristics, production costs and weight. Linde + Wiemann also displayed a section with a complex contour and varying cross section, which featured a continuous weld made using the ATEC form fixture process. This process works in much the same way as hydroforming, albeit with a gaseous medium and the application of temperable high-strength steel, as press-hardened components do.
High-strength, thin-walled aluminium structural cast parts produced by Honsel, light metal processing specialists, were used for the structural nodes at the rear and in the B-column of the EDAG "Light Car - Open Source". Numerous extruded sections, some of them in innovative multi-chamber designs, were also used by our open source partner Honsel. One technical highlight is the demonstration of the aluminium node formed using heat and a gaseous medium. On account of the high specific degrees of strength and rigidity, and also the enormous amount of energy needing to be absorbed in the event of a collision, the front panel and boot lid were represented in organo sheet (endless fibre reinforced thermoplastic synthetics). These semi-finished fibre composite products are geared to requirements, and can be reshaped using simple pressing technology in very short cycle times. In this way, low-cost, three-dimensional components become possible, even where large quantities are concerned. This technology was contributed by our open source partner Bond-Laminates.
The need for thin-walled cast steel body components was met through the involvement of our open source partner, CX-Gruppe, a company specialising in casting technology. The exemplary application of thin-walled, high-strength cast steel spans the front structural nodes, floor, door sill and the integral suspension strut domes. This means that it might soon be possible to make ribbed and topologically optimised cast parts in high-performance body structures out of steel, something which was previously limited to aluminium cast parts. The process employed enables walls of a minimum thickness of up to 1.5 mm to be produced. In order to be able to join together the various materials used in the EDAG "Light Car - Open Source", a special mechanical joining process was called for, in addition to traditional welding. High-speed bolting with the RIVTAC®, a hand-held device, is the ideal way of joining aluminium, steel and fibre composites, and even hybrids. Parts can be joined together at an amazing speed, without any need for punching holes beforehand. The process is ideal for joints on bend-proof flanges and for closed sections which can be found numerous areas in the space frame structure of the EDAG "Light Car - Open Source".