This work examines the feasibility of using foamable polymer filaments to create lightweight composite beams using additive manufacturing. To accomplish this, monolithic and sandwich beams, with non-foamed face sheets and a foam core were fabricated using MEX 3D printers. The non-foamed and foamed PLA components were created by extruding foamable PLA with nozzle temperatures of 200 °C and 220 °C, respectively. Tensile testing samples were printed and tested and used to provide data for numerical models. A range of different sandwich structures were printed and tested in 3-point bending and their performance was compared to monolithic non-foamed and foam beams and to analytical and numerical models.

The stiffness, yield load, and maximum load of sandwich beams with non-foamed face sheets and foamed cores are much greater than those of pure foamed beams. With sandwich foam beams, weight reductions of around 30 % are both observed and predicted compared to non-foamed beams with equivalent stiffness. Analytical and numerical models using experimental data show value in aiding the design of sandwich structures of this type.