Mechanical performance of additively manufactured lightweight cellular solids: Influence of cell pattern and relative density on the printing time and compression behavior

A comprehensive investigation is presented on the Fused Filament Fabrication (FFF) technology's possibilities to create cellular solids with a broad spectrum of specific stiffness and strength, modifying cell geometry and size, while addressing manufacturing matters such as inherent defects and built time. Thirteen typologies of two-dimensional cellular patterns with different relative densities are examined. Results have allowed conclusions to be drawn regarding the influence of cell type and infill density on mechanical performance. Intra-layer and inter-layer inherent defects identified after manufacturing highlight the importance of optimizing filament trajectories. A reliable comparison of the elastic properties of the cellular patterns as a function of their density is presented. An experimentally validated numerical model is provided for predicting the compression stiffness of the different cell patterns with an average deviation below 5%. The model can reproduce the behavior in the elastic range based on tensile specimen properties and a Normal Stiffness Factor to account for the phenomenon of elastic asymmetry of the FFF printed samples. The wide range of results achieved is experimental confirmation of the potential of FFF cellular solids. Lastly, this investigation provides analytical, numerical, and empirical validated evidence to further design-for-additive manufacturing strategies with cellular solids for designing advanced lightweight structures.