Researchers develop 3D printed metamaterial that shrinks when heated. Members of Lawrence Livermore National Laboratory’s Additive Manufacturing Initiative are among a group of researchers who have developed 3D printed materials with a unique property — instead of expanding when heated, they shrink.
In a study published in the Oct. 21 edition of the journal Physical Review Letters (link is external), LLNL engineers, along with scientists from the University of Southern California (link is external), MIT (link is external) and the University of California, Los Angeles (link is external), describe the 3D printing of lightweight metamaterials with negative thermal expansion that can be “tuned” to shrink over a large range of temperatures.
“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.”
In the paper, the researchers demonstrate a bi-material microlattice structure, printed from polymer and a polymer/copper composite material that can flex inward, causing the structure to contract when exposed to heat over a range of tens to hundreds of degrees. Researchers note the study may be the first experimental demonstration showing large tunability of negative thermal expansion (NTE) in three Cartesian directions of microlattice structures.
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.
“Traditionally, the way you compensate for (thermal mismatches) is with active control or heating and cooling,” Spadaccini said. “But what if you could design a material that would hold the object and passively adjust to local temperature changes?”