Investigation on the indentation behavior of sandwich beams using crushable and hyperelastic foam cores

In this work the indentation behaviour of sandwich beams is studied adopting the classical approach representing the core material as a Winkler-type foundation. It is shown how most of the proposed theories can be derived from a general fourth order linear differential equation expressing the equilibrium of the indented beam skin. Different assumptions on the supporting boundary constraints and materials constitutive behaviour, lead to simplifications of the general equation and to the prediction of different indentation features. An extension of the Segment-Wise approach recently proposed in the literature is in particular presented with potential to better simulate foam cores with markedly non-linear compressive behavior. Results from experimental indentation tests performed on sandwiches employing thermoplastic based matrices and foams are also presented to supplement the theoretical analysis.