Experimental Investigation of Topology-Optimized Beams With Isotropic and Anisotropic Base Material Assumptions

Abstract

Additive Manufacturing (AM) technologies are promising fabrication methods with the potential to increase customizability and structural complexity. It is well established that the nature of AM typically results in base materials that exhibit an extent of anisotropy. Since topology optimization is a freeform approach that generally achieves high performing designs, it is often suggested as a powerful design-for-AM method. However, most topology optimization frameworks ignore anisotropic effects and assume isotropy of the base material. Although frameworks that consider anisotropy have been suggested, the influence anisotropy has on the physical behavior of fabricated designs is not well understood. Therefore, this work presents an experimental study of topology-optimized structures designed with both isotropic and anisotropic linear elastic material assumptions to explore how much anisotropic considerations matter when it comes to the discrepancy in numerical and experimental performance. The experimental investigation is conducted using a Fused Filament Fabrication print process that allows us to prescribe the anisotropy. The Young’s Modulus of the designated print setup is experimentally determined and used for design of 3D simply supported beams with various material volumes. Samples are fabricated and evaluated using 3-point bending tests. It is seen that the isotropic designs have a slightly better average performance at the design load (1.8–2.0%), but that inclusion of the anisotropic behavior significantly limits behavioral differences across samples (84.4–171.5% decrease in standard deviation) and improves the print success rate.