Numerical and experimental investigation of the joint stiffness in lattice structures fabricated by additive manufacturing

In this paper, a concept called joint stiffening element is proposed to represent the influence of the joint on the stiffness of lattice structures fabricated by additive manufacturing. Four parameters are defined in the proposed element to quantify the increment of the stiffness caused by the lattice joint. Then, three-point-bend testing is used to validate the proposed model. The lattice structures with Cubic-center and Vintiles topologies are designed and fabricated for the experiment. As-fabricated material properties are obtained by tensile specimens to eliminate the influence caused by the manufacturing process and to isolate the joint stiffening effect. The result shows that models with the solid element and the proposed element are both accurate, but the proposed model has a significantly less computational cost than the solid element model. Furthermore, compared to the beam element model, the proposed model can more accurately estimate the stiffness of lattice structures, especially for the Vintiles topology. It is also found that the joint stiffening effect is more significant on the bending dominant topology than the stretching dominant topology.