On the design of new tram vehicles based on the alusuisse hybrid structural system

In close cooperation with the leading suppliers of modem mass transit vehicles a hybrid design concept has been developed for body shells that uses longitudinal hollow aluminum extrusions combined with foam core sandwich panels of aluminum face layers. In addition to the reduction of mass, the hybrid design helps to save production costs. These savings are primarily based on the simplified assembling technique via the new Alusuisse Alugrip corner bolt system and via viscoelastic adhesives. Furthermore, the insulation inherent to foam core sandwich shells and the outstanding impact behavior offer additional benefits to the final customer. Based on the example of a new low floor tram vehicle the essential features of the hybrid structural concept are described. In order to improve the fatigue behavior of the vehicles, a special joining technique linking orthogonal aluminum extrusions without any welding operations has been developed (i.e., the Alugrip system). The joining of the sandwich composite elements to the aluminum extrusions is a further challenging design step in the development of a hybrid structure. In order to meet all the structural criteria complex finite element analyses have been performed. The structural integrity of the body shell has been proven in statical testing and in operation.