Infill shape effects on bending stiffness of additively manufactured short fibre reinforced polymer sandwich specimens

Additively manufactured polymer parts are often designed like composite sandwich structures. In this work, sandwich beam-like specimens with hexagonal, triangular and rectangular infills were manufactured with different infill densities. An influence of the shape of the infill on the overall stiffness was observed. The bending stiffness of the hexagonal specimens was between 13% and 25% lower than that of the other two cases that instead showed similar performances. Numerical simulations were performed using both shell and solid elements for the infill, to check if it was possible to model the differences observed experimentally. All simulations lead to accurate bending stiffness predictions, except for the rectangular infills with higher infill densities, for which overprediction between 20% and 25% was obtained. Based on these results, strategies for the finite element analysis of additively manufactured composite structures are discussed.