Optimization for Anisotropy in Additively Manufactured Lattice Structures

Abstract

The build orientation of fabricated parts is one the most influential factors affecting material properties in many Additive Manufacturing (AM) processes. Applications such as the optimization of lattice structures for AM, are particularly affected as knowledge of the anisotropy model of the material is crucial. The investigation in this paper shows the influence of material anisotropy and build orientation on the optimized lattice structure designs. First, a material property characterization study for both compression and tension states of a single material is carried out for the example of inkjet 3D printing. Then, a generalized optimality criteria method is extended for the optimal sizing of single material and fixed topology lattice structures with respect to displacement, stress and Euler buckling constraints. The stress and Euler buckling constraints are formulated as side constraints that are handled in combination with fully-stressed design recursion. The results demonstrate the effect of anisotropy on the optimized designs caused by individual struts’ build orientation. This demonstrates the need to include anisotropic models in the optimization in order to produce solutions that can be fabricated and tested.