trailer world Issue Two 2012

26 Issue Two 2012 Innovation Photos:TeufelbergerGes.m.b.H.,OliverWillms,BPW nering without the fear losing contact when approaching the stability limits of the chas- sis”, is just one of the arguments put forward by HBN expert Dr. Fleischhauer in favour of using the new material. Combining steel with GRP The successful formal implementation of the GRP axle sys- tem developed in finite element modelling still has to be seen in the overall context of the complex issue of fastening those com- ponents that still have to be made of steel. These include the air spring support, fit- ting the shock absorber and connecting the steering knuckle which takes the brake and wheel carrier. The durable transition from GRP to steel is no trivial issue. To integrate the necessary jacks for connecting the air spring support with the GRP module, the HBN ex- perts use a so-called loop connection that is braided in a precisely calculated fibre compos- ite in circular fashion around a plastic bushing of the shaft to permit optimum transmission of force via the steel suspension into the GRP body. Hitherto, loop connections of this kind were used in GRP solutions among others for fuel tank retaining straps, in rotor structures for helicopters and in prototype applica- tions for wind turbine rotors. High strength requirements Admitted- ly, the liaison between GRP and steel gets tricky where the greatest forces occur - at the transition from the axle body to the steering knuckle, at the so-called wheel ends. Here the connection has to withstand axle loads of up to 27 tonnes. The bonding technique used in the past for large contact surfaces primarily in lightweight aircraft construc- tion or also in the GRP project by Willig (see page 32) is not suitable in the opinion of plastics expert Dr. Fleischhauer on account of the critical long-term strength, the ther- mal load generated by the waste heat of the wheel brake and the higher requirements in terms of production quality assurance. Nor do customers appear to be very willing to accept bonded connections, adds the GRP expert whose company Composcience co- operates closely with TU Darmstadt. An- other possibility for the durable connection of the axle knuckle to the axle body could consist in pressing a metal bushing – a safe GRP – the multi-talent fibre composite Lightweight, robust, mechanically strong, suitable for almost any shape, resistant to ageing and economical in terms of raw material procurement. Glass-fibre reinforced plastic combines the advantages of various substances in one material. It is based on glass-fibre rods made of silicon that are impregnated with epoxy or polyester resins or with polyamides which cure into a durably stiff but not inelastic structure. Used since the 1930s, the material has proven its worth above all in boats and aircraft. Except with mobile applications, GRP is also used in plant construction, in tanks and containers or as structural material for large rotors in wind turbines. Depending on fibre length and pattern, the material can be given a wide range of different resilience and elasticity properties. Compared to high- strength carbon fibre-reinforced plastic (CRP), the material for GRP costs only around one tenth. This also permits its use in more weight-intensive commercial vehicle production. Fibre braiding machine at work (left). The “T-Igel” (middle) creates a “smart” connection between GRP and steel, say Teufelberger expert Herwig Kirchberger and HBN fibre professional Dr. Martin Fleischhauer (right). »We are driven by lightweight construction. The ECO Vision axle made of GRP fibre composite brings a payload advantage of 80 kilos.« Dr. Martin Fleischhauer, HBN-Teknik

trailer world Issue Two 2012

Pages