Determination of the dynamic behaviour of thin-walled hollow-box sandwich beams

Sandwich geometries, mainly panels and beams are widely used in several transportation industries, namely aerospace, aeronautic and automotive. They are known for some advantages in structural applications: high specific stiffness, low weight, and possibility of design optimization prior to manufacturing. This study aims to discover the dynamic behaviour of simply supported at its ends Finite Element Method (FEM) models, representing a novel type of sandwich beams. There are 24 examples of geometries discussed with the same base configuration. The models were previously subjected to a design optimization routine. Dynamic behaviour of the initial models in relation to their final versions is considered. Influence of the geometry on the characteristic frequencies is discussed, as well as its improvement in relation to the initial models. It is shown that the statically optimized models represent a significant improvement over the initial ones, as some improvement of the characteristic frequencies is obtained for most cases. By improvement here it is understood their values for the optimized model are higher than those for the corresponding initial one. In fact, the frequencies are more energetic the lower they are. As such, lower values represent higher probability of disturbance of the correct operation of the beams in applications comprising mobile parts. Some example of such application can be laser cutting machines or industrial printers.