Compression and flexural properties of rigid polyurethane foam composites reinforced with 3D-printed polylactic acid lattice structures

Lightweight rigid polyurethane foam (RPUF) composites with favorable mechanical properties are demanded by numerous engineering applications. The mechanical performance of foam composites could be customized and enhanced by embedding geometric skeletons. The advancement of 3D printing technology has enabled greater freedom in manufacturing geometrically complex products. In this paper, two types of lattice structures were 3D printed with fused filament fabrication (FFF). Structural composites were prepared by filling the lattices with RPUF through the free rising method. Experimental testing and FEA modeling demonstrated that the lattice structures had significant effects on the composites' stress dissipation and fracture forms. Compared to neat RPUF, the composites exhibited greater elastic limit, compression modulus, energy absorption capabilities, flexural strength, and flexural modulus. Lattices with more struts and greater density resulted in superior compression and flexural performance. This study shows that FFF lattices are suitable for constructing RPUF composites with enhanced flexural and compression properties.