On Strength Variations Effected by Infill Patterns Such as Honeycomb, Gyroid, and Archimedean Chords Used in Additive Manufacturing.

Additive manufacturing delivers internal substructures that alter the mechanical performance, yet their exploitation is still limited in structural part design, to a certain degree due to the absence of comparative studies. All slicer software solutions can exchange the infill with predefined infill patterns. Often their performance properties are unknown, and engineers make choices that depend on the printing time or material use. We conduct an experimental campaign to understand infill patterns' effect on the mechanical performance. This work is inspired by biomimicry and studies honeycomb-, gyroid-, and Archimedean chords-type infill patterns in order to determine their performance. Experimental analysis via the three-point bending test has been conducted by using samples from PolyLactic Acid (PLA) with infill densities of 50, 60, 70, 80, 90 and 100% for these infill patterns. An additional set of samples was printed with Acrylonitrile Butadiene Styrene (ABS) for additional evaluation of Archimedean chords. We characterize the mechanical performance by comparing strength properties and observe that a mass-normalized flexural strength measure is meaningful when selecting an adequate infill pattern. Honeycomb showed the highest absolute flexural strength; strength per mass peaked at 90% infill. Mass reduction effected by infill density reduction fails to be linear; lowering infill down to 50% decreases mass marginally by up to 17% only. The performance of each infill pattern and comparisons between mass, strength, and print time are described to serve as a guide for designers.