If you can imagine it, you can print it—this is the promise of additive manufacturing, more commonly known as 3D printing, which allows individuals and organizations to design a wide range of structures and produce them cheaply and reproducibly.
“Lattices are perhaps the ultimate application of 3D additive manufacturing because they are intricate structures that can utilize very little material to fill a volume while still providing structural rigidity,” said Stefanie Feih, a Senior Scientist who leads the Polymer Processing Group at A*STAR’s Singapore Institute of Manufacturing Technology (SIMTech).
She added that lattices also absorb impact energy well, providing insulation from vibration and noise. Moreover, they can be used to provide effective thermal insulation, or maximize heat transfer, thanks to their high surface-area-to-volume ratio.
“The conventional state-of-the-art approach in lattice design is to simply repeat a unit cell over and over throughout a given volume, to give a uniform array of struts,” Feih explained.
Recognizing an opportunity to expand the possibilities of lattice design by modifying the dimensions of each repeating unit cell, Feih’s team, with collaborators at the National University of Singapore, devised a computational approach to vary the spacing, length and orientation of lattice beams throughout a structure. This allowed the researchers to generate what is known as graded lattice infill arrangements, which can be optimized for strength.
“Our novel design approach integrates data about how force is aligned throughout a structure,” said Stephen Daynes, a Scientist at SIMTech and the lead author of the study. “By creating an interconnected network where the beams are aligned with the paths experiencing the most strain, we were able to improve the structural performance of the lattice using the same amount of material distributed more efficiently.”
Daynes and the team validated their methodology by designing two common engineering components—a floor beam and a spider bracket. “Our method resulted in a floor beam that is 3.5 times stiffer than a commercially-optimized square cell lattice infill of the same mass,” said Daynes.
Meanwhile, for the spider bracket, the researchers designed a structure which had less overhang, thereby removing the need for support materials during production. The tradeoff? Only a small reduction in stiffness. The researchers have filed a US patent application for their lattice design approach.
Daynes highlighted that their technique could also be used to minimize buckling or yielding in 3D-printed lattice structures. “We also believe that these lattices can have favorable heat transfer properties since they have a much larger surface area than equivalent solid components. We are exploring how best to take advantage of this property,” he said.
The A*STAR-affiliated researchers contributing to this research are from the Singapore Institute of Manufacturing Technology (SIMTech).