Modified beam modeling of powder bed fusion manufactured lattice structures

In this work a modified beam approach to model the compressive behavior of additively manufactured BCC and reinforced BCC lattice structures is proposed. Three-dimensional beam models are of interest because of their reduced computational time, with respect to numerical models that involves solid mesh elements, but they are not able to capture the behavior of lattice structures in proximity of the unit cell nodes, that presents higher stiffness due to the struts intersection and consequent material overlapping. In order to overcome this drawback when using beam finite elements, a modified beam approach is used in this work considering each lattice cell strut subdivided in a central flexible portion and two rigid extremities. A numerical procedure is implemented to tune the rigid extremities length of the strut by means of numerical simulations that aims to reproduce accurately the compressive behavior of the lattice cell solid model. The experimental campaign conducted on different powder bed fusion manufactured lattice structures is presented and experimental results are provided along with a numerical-experimental correlation that proves the accuracy of the method.