Modelling of damage and plasticity phenomena in 3D printed materials via a multiscale approach

A multiscale technique able to describe the overall mechanical response of 3D printed materials taking into account the plastic behaviour and the occurrence of failure is presented. Reference is made to elements produced by extrusion-based additive manufacturing. At the microscale, the de-cohesion between filaments that constitute the printed material is described introducing a cohesive damage interface model that also takes into account the unilateral contact. The micromechanical problem is solved with a homogenization procedure based on the PieceWise Uniform Transformation Field Analysis properly extended to the case of interfaces. In detail, the plastic strains in the filaments and the inelastic relative displacements along the interfaces are approximated as piecewise constant functions and then are computed solving the evolutive problem. Some numerical applications are carried out, comparing the numerical results with the experimental ones and with results obtained from non-linear finite element analyses, to show the potentiality of the proposed multiscale technique.