Innovative Vehicle Concept for the Integration of Alternative Power Trains

Kurzfassung

Abstract: The Institute of Vehicle Concepts is developing a safe, modularisable vehicle concept in rib and space frame design for tomorrow’s vehicles with alternative power trains. The vehicle can be powered either by a fuel cell system, a free-piston linear generator developed at the DLR, or a traction battery. Taking into account the given boundary conditions, the challenge is to design a body structure that is light and performs well in the event of an accident. The rib and space frame concept for the vehicle body has a crash compartment in the floor to hold alternative power train components. Crash elements made from carbon fibre reinforced polymer (CFRP) are inserted between the crash compartment, formed by two continuous side members, and the outer rocker panels. The body consists of three annular ribs made of fibre-reinforced plastic, which are joined by means of simple geometric profiles or cast nodes. In a second design, support structures are integrated into the vehicle that significantly increase weight-specific energy absorption by means of systematic elongation. The crash compartment serves to ensure that there is no danger by the alternative power trains, in this case particularly the energy storage systems, during an accident. In the event of a side impact, the annular ribs protect the passengers by keeping the survival space intact. Furthermore, the use of composite structures reduces the weight of the vehicle body considerably compared to a reference structure with the same level of safety. In the case of extreme local strain arising from a pole collision, hybrid support structures consisting of a foam core and a metal profile reduce intrusion into the passenger compartment. Suitable materials are particularly metals with a high degree of weight-specific strength and elasticity such as stainless steel or the newly developed manganese steel, but also aluminium alloys with high elasticity. The B-rib, which takes the most strain, is available as a structure tested for side impact as defined by Euro NCAP, and will shortly be subjected to the American IIHS test. Hybrid support structures for different combinations of materials were also tested at component level. The space frame is being constructed as a digital prototype on which different subsystems can be examined virtually in terms of energy absorption and their effect on the vehicle mass. The lecture will discuss the simulation results and prototype tests for the B-rib and the hybrid support structures, as well as the current status of rib and space frame construction.