The Application of Sandwich Components in Hybrid Structures

Abstract

A hybrid design concept for body shells has been developed in order to achieve light and stiff structures for state of the art railway and bus vehicles. It uses longitudinal hollow aluminum extrusions combined with foam core sandwich panels of aluminum face layers. In addition to the reduction of mass, hybrid design helps to save production costs. These savings are based on the simplified assembling technique in a modular concept (via corner bolt systems, viscoelastic adhesives, riveting and laser welding), the integration of insulation (by the foam core), and the outstanding impact behavior. The direct joining of the sandwich composite elements to the aluminum extrusions is, however, one of the most challenging steps when designing a hybrid structure. For this reason the hybrid design concept requires a more sophisticated structural analysis approach. In the case of the composite components reduced shear stiffness of the core and local failure mechanisms have to be taken into account. In order to meet all the structural criteria detailed finite element models and analyses have been derived. Several examples of railway structures built in the hybrid design are given to show the development steps and the advantages of this new design concept.