JEC COMPOSITES MAGAZINE - Issue #45 - November/December 2008 - 37

Thermoplastics the tailgate consisted of an ABS-PC inner part with flap. The storage space was used for the roof edges, which were fastened with belts that could retain them in a front crash situation (Figure 5). The sledge test results were very good. For all configurations and temperatures, the two roof edges were retained without failure of the inside lid. It was also shown that the simulated behaviour of the structure agreed very well with its actual performance. Design concept The first developmental step was to work out an E-LFT solution for the tailgate. Series development and mass production The concept validation data were used to further develop the E-LFT tailgate, which was numerically optimized in conformance with the stricter crashworthiness requirements currently in force, and tested in sledge and full-vehicle crash tests. The E-LFT tailgate passed both tests and met all other test requirements (e.g. lid endurance for 50,000 load cycles under climatic conditions) and various full-vehicle tests in actual operation. Fig. 6: The new E-LFT tailgate solution for the coupe and cabrio models. The tailgate structural concept combines an inner part with storage space and an inside lid. In this E-LFT solution, the roof edges are retained by the inside lid in a crash and no longer require fastening belts. This new concept provides considerable freedom for configuring the storage bin and simplifies roof edge storage. The new solution achieves the following goals: • expanded loading/storage space through integrated E-LFT storage bin • roof edges (cabrio) stored without additional fastening belts • multi-functional storage bin for both coupe and cabrio models • same structural concept for all versions • completely visible grained, moulded-in-colour E-LFT component surface • integration of different accessories and storage concepts • high customer utility • low investment, thanks to identical parts. The structural concept was designed by numerical simulation and validated by appropriate tests. The main emphasis was on the behaviour of the inside lid in a frontal crash: to ensure occupant safety, the lid has to retain the two roof edges (5.2 kg) at 64 km/h with the very high pulse peak typical of compact cars. The concept was designed and tested for room temperature, -30°C and +60°C. Esoro introduced a new test rig where three component configurations can be tested in a single sledge test. Fig. 8: E-LFT coupe tailgate (left), E-LFT cabrio tailgate (right). Production of the E-LFT tailgate started in January 2007 in Weber Fibertech’s newly-built production site in Markdorf, Germany. Weber Fibertech is a division of Weber Automotive, which holds the patent rights of the E-LFT process. The production site is equipped with a 3,600 ton press, an LFT-DILC unit for LFT compounding, an EF processing line and several robots for fully-automated production. At present, 700 tailgates are produced daily. Fig. 9: Weber Fibertech mass production plant in Markdorf, Germany. Results Structural rigidity was increased by more than 20%, compared to the previous models. The E-LFT cabrio tailgate weighs as much as the earlier cabrio version made from ABS-PC, whereby the projected area was slightly larger and the crashworthiness requirements are also tighter. Compared with earlier coupe Fig. 7: Sledge test with rig for three tailgates. No45 November-December 2008 / jec composites magazine

JEC COMPOSITES MAGAZINE - Issue #45 - November/December 2008

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #45 - November/December 2008