  Recent advances in active materials and fabrication techniques have enabled
the production of cyclically self-deployable metamaterials with an expanded
functionality space. However, designing metamaterials that possess continuously
tunable mechanical properties after self-deployment remains a challenge,
notwithstanding its importance. Inspired by push puppets, we introduce an
efficient design strategy to create reversibly self-deployable metamaterials
with continuously tunable post-deployment stiffness and damping. Our
metamaterial comprises contracting actuators threaded through beads with
matching conical concavo-convex interfaces in networked chains. The slack
network conforms to arbitrary shapes, but when actuated, it self-assembles into
a preprogrammed configuration with beads gathered together. Further contraction
of the actuators can dynamically tune the assembly's mechanical properties
through the beads' particle jamming, while maintaining the overall structure
with minimal change. We show that, after deployment, such metamaterials exhibit
pronounced tunability in bending-dominated configurations: they can become more
than 35 times stiffer and change their damping capability by over 50%. Through
systematic analysis, we find that the beads'conical angle can introduce
geometric nonlinearity, which has a major effect on the self-deployability and
tunability of the metamaterial. Our work provides routes towards reversibly
self-deployable, lightweight, and tunable metamaterials, with potential
applications in soft robotics, reconfigurable architectures, and space
engineering.
