3D printed metamaterial that shrinks upon heated

Members of Lawrence Livermore National Laboratory’s Additive Manufacturing Initiative are among a group of researchers who have recently developed 3D printed materials with a unique property — instead of expanding when heated, they shrink.

“This is a new version of a printing method we have developed and used in the past. We used it to create a thermomechanical metamaterial that may enable applications not possible before,” said principal investigator Chris Spadaccini, director of LLNL’s Center for Engineered Materials and Manufacturing. “It has thermomechanical properties not achievable in conventional bulk materials.”

Possible applications for the metamaterials, the researchers concluded, could come in securing parts that tend to move out of alignment under varying heat loads, including microchips and high precision optical mounts. A team at MIT, led by Associate Professor of Mechanical Engineering Nicholas Fang, 3D-printed the microlattice structures using a projection microstereolithograpy process. USC Assistant Professor of Civil and Environmental Engineering Qiming Wang, the paper’s lead author, worked for Fang as a postdoc.

Wang said the microstructured metamaterial could be used in dental fillings, which tend to move or crack when a person eats something hot, to fill in small gaps in bridges or buildings that are normally left open to account for thermal expansion, or in precision devices such as atomic-force microscopes. The study is part of a five-year Defense Advanced Research Projects Agency Defense Sciences Office program to research materials with controlled microstructure architecture.