Study of manufacturing defects on compressive deformation of 3D-printed polymeric lattices

This paper studies theoretical, numerical, and experimental studies on static compression behaviour of polyamide 12 body-centred cube (BCC) lattices manufactured using the selective laser sintering (SLS) method. In the analytical formulation, the influence of imperfections that happened during 3D printing such as material overlapping in the vicinity of filament joints is considered to provide predictions of mechanical properties of a macro lattice structure. Finite element (FE) models of the BCC lattices are performed to predict the compressive behaviour and deformation localisation of filaments. In order to determine a material model and input parameters for FE simulation of the lattice cubes, an individual 3D-printed filament is subjected to transverse compressive loading utilising a custom-made filament compression rig. Then, true experimental stress and strain data are generated that are imported into an inverse calibration technique using MCalibration software to determine the material parameters for the FE simulation. A series of BCC lattice cubes were printed using the SLS method. Compression experiments were conducted utilising digital image correlation (DIC) techniques in order to determine localisation of deformations and strains and validate the material properties obtained by the analytical modelling and numerical simulations. Good agreements are observed among the analytical, numerical, and experimental results. The results show that effect of filament defects should be taken into account to find the accurate responses in analytical model and FE simulation.