Deflection-Constrained Topology Optimization of Structures with Graded Infill

The design of composite structures consisting of full material and a prescribed fraction of graded infill is dealt with, focusing on the enforcement of multiple displacement constraints. Numerical homogenization is used to derive the macroscopic elastic properties of two isotropic infills that are used in additive manufacturing. A two-phase material law with void is implemented to control both the amount and the density range of the graded infill. Full material and infill are distributed in the design domain by means of topology optimization. An augmented Lagrangian technique is adopted to solve the arising optimization problem, addressing multiple load cases with distributed loading. Numerical simulations are shown to compare optimal composite structures with a conventional truss-like design.