Abstract
The aim of this paper is to introduce and characterize, both experimentally and numerically, three classes of non-traditional 3D infill patterns at three scales as an alternative to classical 2D infill patterns in the context of additive manufacturing and structural applications. The investigated 3D infill patterns are biologically inspired and include Gyroid, Schwarz D and Schwarz P. Their selection was based on their beneficial mechanical properties, such as double curvature. They are not only known from nature but also emerge from numerical topology optimization. A classical 2D hexagonal pattern has been used as a reference. The mechanical performance of 14 cylindrical specimens in compression is quantitatively related to stiffness, peak load and weight. Digital image correlation provides accurate full-field deformation measurements and insights into periodic features of the surface strain field. The associated variability, which is inherent to the production and testing process, has been evaluated for 3 identical Gyroid specimens. The nonlinear material model for the preliminary FEM analysis is based on tensile test specimens with 3 different slicing strategies. The 3D infill patterns are generally useful when the extrusion orientation cannot be aligned with the build orientation and the principal stress field, i.e., in case of generative design, such as the presented branching structure, or any complex shape and boundary condition.
Highlights
By integrating the computational design and digital fabrication process, additive manufacturing (AM) has developed over the last decades into various forms, providing architects and designers with efficient tools for rapid prototyping, individualisation and low-volume production
The results of the cylinder compression tests are presented and discussed in subsection Experimental and relate to the performance of various infills, while the results of the dog bone tensile tests are presented in the subsection Numerical, where they relate to the actual PLA material and anisotropy of 100% infill resulting from different slicing strategy
The linear trend lines show that both in terms of stiffness and peak load, the 2D hexagonal infill outperformed the tested 3D infills, which is not surprising considering that the extrusion axis of the pattern is aligned with the axis of the macroscopic member and the principal stress field
Summary
By integrating the computational design and digital fabrication process, additive manufacturing (AM) has developed over the last decades into various forms, providing architects and designers with efficient tools for rapid prototyping, individualisation and low-volume production. 3D printing is traditionally utilized for rapid prototyping and for high-value, low-volume production, such as in the aerospace industry, the last years have seen many successful efforts in upscaling the 3D printing systems to structural and architectural scales. Most of such large scale 3D printing systems are, still to be considered rather experimental. This applies to autonomous construction systems in general, where autonomous and self-sufficient robots perform the 3D printing, and manipulation or excavation tasks [1]
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