Non-standard coupled extensional and bending bias tests for planar pantographic lattices. Part II: comparison with experimental evidence
Résumé
In [1] and [2] pantographic sheets are proposed as a basic constituent for a novel metamaterial. In Part I, see [3], two different numerical models are applied in order to design an experimental set up aimed to prove the effectiveness of introduced concept. The aim of this paper is to prove that the Hencky-type model introduced for planar pantographic sheets allows for the correct prediction, in a large range of imposed displace- ments, of the experimental measurements concerning specimens undergoing coupled bending and extensional deformations. The four-parameters numerical model introduced is shown to have a large range of applicability: indeed without changing the values of the material parameters previously attributed in simple extensional tests to a specific specimen by a best fit procedure, it is possible to forecast its behaviour in all the considered type of imposed deformations. The measurements performed include the determination of reactive forces exerted by used hard devices and the numerical modelling is able to predict very carefully quantitatively and qualitatively also this complex aspect of phenomenology, where previously attempted models seem to have failed.