FE Modelling of Cellular Materials Under Compressive Load

Abstract Structures made of tubes, stacked in square or hexagonal patterns, have been considered here as model cellular materials. Compression tests have shown large deformations, transformations and also many contact points. Two Finite Element codes have been used to investigate the influence of the elements type (quadrangular or triangular, linear or quadratic) and the numerical scheme (implicit or explicit) on the structural numerical responses. A contact algorithm based on the Pinball method has been implemented in the explicit code. A very good agreement has been found between the predictions of both codes. The numerical responses are close for a given meshes order, whatever the elements type. Whereas the linear meshes cannot be considered as converged, the quadratic meshes predict very well the experimental responses of the structures, especially for the square stacking. The overestimation of the numerical response of the hexagonal stacking might be explained because, experimentally, this stacking exhibits a more scattered and irregular behaviour due to defects (missing brazes, tube misalignment) which were not modelled.