J.U. Surjadi; B.F. Aymon; M. Carton; C.M. Portela
Nature Materials 24 (2025) 945–954
Mechanical metamaterials can achieve high stiffness and strength at low
densities, but often at the expense of low ductility and stretchability—a
persistent trade-off in materials. In contrast, double-network hydrogels
feature interpenetrating compliant and stiff polymer networks, and exhibit
unprecedented combinations of high stiffness and stretchability, resulting
in exceptional toughness. Here we present double-network-inspired
metamaterials by integrating monolithic truss (stiff) and woven (compliant)
components into a metamaterial architecture, which achieves a tenfold
increase in stiffness and stretchability compared to its pure counterparts.
Nonlinear computational mechanics models elucidate that enhanced
energy dissipation in these double-network-inspired metamaterials stems
from increased frictional dissipation due to entanglements between
networks. Through introduction of internal defects, which typically degrade
mechanical properties, we demonstrate a threefold increase in energy
dissipation for these metamaterials via failure delocalization. This work
opens avenues for developing metamaterials in a high-compliance regime
inspired by polymer network topologies.