A method to represent impacted structures using scaled models made of different materials

• An approach that relates prototype and models of different materials is proposed.
• Adopting a mass dimensionless number allows to compensate density differences.
• Strain-rate effects are considered but are less important than density differences.
• Discrepancies due to differences scaled stress–strain curves can be forecasted.

A technique that deals with scaling of structures under dynamic loads is studied here. It is assumed a model whose material is different from the prototype so generating incomplete similarity. In order to handle this problem, a method was developed that allows the use of different densities and mechanical properties for replica and full-size structures. As a means to verify the technique, an analytical solution for beams under impulsive load and numerical simulations of scaled plates subjected to dynamic loads is explored. The theoretical solution shows that the structure density can play an important role. The complete similarity can only be achieved if the density scaling factor is taken into account, mainly for structures in which the inertia is comparable. The numerical investigations show that discrepancies between the scaled variables of model and prototype are substantially reduced when the present method is applied, even for material as different as steel and magnesium. The limitations caused by the use of different materials for model and prototype are thoroughly discussed.