title: Ultralight, ultrastiff mechanical metamaterials.
abstract: The mechanical properties of ordinary materials degrade substantially with reduced density because their structural elements bend under applied load. We report a class of microarchitected materials that maintain a nearly constant stiffness per unit mass density, even at ultralow density. This performance derives from a network of nearly isotropic microscale unit cells with high structural connectivity and nanoscale features, whose structural members are designed to carry loads in tension or compression. Production of these microlattices, with polymers, metals, or ceramics as constituent materials, is made possible by projection microstereolithography (an additive micromanufacturing technique) combined with nanoscale coating and postprocessing. We found that these materials exhibit ultrastiff properties across more than three orders of magnitude in density, regardless of the constituent material.
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, CA 94550, USA. zheng3@llnl.gov spadaccini2@llnl.gov nicfang@mit.edu.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Howon
authors.initials: H
authors.lastname: Lee
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
authors.forename: Todd H
authors.initials: TH
authors.lastname: Weisgraber
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
authors.forename: Maxim
authors.initials: M
authors.lastname: Shusteff
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: DeOtte
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
authors.forename: Eric B
authors.initials: EB
authors.lastname: Duoss
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Kuntz
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
authors.forename: Monika M
authors.initials: MM
authors.lastname: Biener
authors.affiliation: Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Qi
authors.initials: Q
authors.lastname: Ge
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Jackson
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
authors.forename: Sergei O
authors.initials: SO
authors.lastname: Kucheyev
authors.affiliation: Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. zheng3@llnl.gov spadaccini2@llnl.gov nicfang@mit.edu.
authors.forename: Nicholas X
authors.initials: NX
authors.lastname: Fang
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, CA 94550, USA. zheng3@llnl.gov spadaccini2@llnl.gov nicfang@mit.edu.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Spadaccini