No abstract

In the past ten years many new processes for making foamed metals, mostly aluminium or aluminium alloys, have been developed. As a matter of fact, closed-cell aluminium foam offers a unique combination of properties such as low density, high stiffness, strength, and energy absorption capability.One of the main differences in the mechanical behaviour of cellular materials with respect to classical homogeneous materials such as solid metals is that foam failure is not independent from a hydrostatic state of stress. Therefore, it is not possible to describe the failure surface from a single, usually uniaxial, test but it is necessary to perform tests with different combination of deviatoric and hydrostatic stress components.Within the European Project APROSYS, whose main objective is increasing the safety of all road-users, the mechanical behaviour of aluminium foam, under multiaxial loading, was investigated by the authors. In this paper the results of the hydrostatic and hydro-compression experimental tests are reported. From the results of these tests, it has been possible to obtain the yield locus of the aluminium foam in the deviatoric-hydrostatic stress components space.

A multibody model describing the behaviour of an M3 class coach in a rollover was developed. The model was validated by comparing the numerical results with the results of experimental rollover tests performed within the enhanced coach and bus occupant safety project. Through such numerical model, the approval tests, stated in the ECE66 regulation, were analyzed in depth. The simulations showed that the presence of passengers onboard, not taken into account in the regulation, considerably affects the deformation of the structure. The calculations showed as well that such influence on the deformation of the structure is strongly dependent on the passenger restraint configuration. The injury risk for passengers of coaches in a rollover accident was evaluated through the use of the mathematical model of crash test dummies. The simulations showed that the use of safety belts considerably reduce the injury risk.