Dynamic characterization of fused deposition modeling-printed polymers with variable infills using homogenization techniques

Abstract

Fused deposition modeling (FDM) printing is a common type of additive manufacturing, which builds up a 3-D volume by laying down filament layer-by-layer. To save material and reduce weight, many commercial software packages utilize infill, which is a repeating lattice pattern with a lower density than the solid material. Users can specify the density of the lattice, as well as the geometry of lattice, with as many as a dozen pre-designed options available to choose from in some commercial software packages. The lattice designs have impact on mechanical and dynamic properties, such as speed of sound, of the finished product. Despite the strong effect on final acoustic performance of infill, until now there has not been a methodical approach to predict the relationship between infill as a design parameter and dynamic properties. In this study, we use finite element analysis to implement homogenization techniques commonly used to study metamaterials in order to predict directional sound speeds for infills over a range of densities. The base material used in the study is polylactic acid (PLA). Additionally, samples with various infills are printed and sound speeds are measured. The experimental results are compared to predicted values.