Using Simple Estimates for the Flexural Stiffness of Thick FDM Beams Based on Sandwich Beam Models

Purpose The incipient growth of the fused deposition modeling (FDM) techniques encourages the development of models to predict the behavior of these parts involving complicated and heterogeneous geometries whose behavior strongly diverges from the continuous model hypothesis. This paper aims to address the problem of predicting the flexural properties of FDM parts building on the geometrical similarity between a typical FDM part and a sandwich panel. Design/methodology/approach This paper takes advantage of the morphological similarity between FDM structures and composite sandwich panels. Thus, an approach based on classic sandwich theory is developed to validate its goodness to predict the flexural behavior of FDM parts. A set of tensile and flexural tests for FDM parts were conducted varying the density of the core pattern (10%, 15%, 20% and 25%), being the proposed model and the predicted results validated. Findings The results showed a good accordance between the predicted values of stiffness and the experimental data. Although this is especially evidenced for low infill density values, for densities above 20% the experimental values noticeably exceed the maximum predicted stiffness, which can be explained by the non-compliance of the foil honeycomb hypothesis for high-density patterns. The main implication of these findings lies in the possibility of using advanced models from thin-foil structures as a base to develop accurate analytical approaches to model FDM structures. Originality/value Although the experimental characterization of FDM parts has been a matter of study in the literature, the development of robust theoretical models that consider the influence of the particular morphology of these parts is still a challenge in this field. The approach proposed in this study constitutes the first step to develop a complete analytical model to predict the complex behavior of FDM printed parts.