23 Sep 2025

Topology Optimization for 3D Printing-Driven Anisotropic Components Accounting for Stress and Displacement Constraints

Abstract: Concrete 3D printing produces a layered macrostructure with different properties in three orthogonal directions, while new techniques allow printing at different orientations. Can printing with spatially variable layer-to-layer interface orientations produce lighter structures while stress and displacement limits are met? This study establishes the connection between experimentally measured properties of printed concrete samples and parameters of orthotropic elasticity and orthotropic yielding. Building upon this connection, a topology optimization framework is built that minimizes weight with respect to the material distribution and spatially variable layer orientation, while simultaneously addressing stress and displacement constraints. This framework is implemented via the Augmented Lagrangian approach and the Method of Moving Asymptotes, and sensitivities are calculated using the adjoint method to reduce computational cost. To expedite convergence without constraint violations, the concept of offset tolerances is introduced and by introducing a cubic term in the displacement constraints accelerating it at large constraint violations and introducing a density-weighted change norm for the orientation angles to eliminate the effect of inconsequential orientation variations in regions of negligible density. This framework enables investigation of fixed vs. variable orientation, tension-compression asymmetry vs. symmetry in achieving low weights, and the relative effect of stress vs. displacement constraints in minimizing weight.