1D to 3D multi-stable architectedmaterials with zero Poisson's ratio and controllable thermal expansion

Multi-stable mechanicalmetamaterialswith unprecedentedmechanical/physical properties have attracted great
interests due to their functional applications for advanced materials and devices. However, the original curved/
tilted bistable snapping segments inmost of those existingmulti-stablemechanicalmetamaterials cause unequal
bistability/multi-stability. The relative thicker supporting segments can't provide complete constraints at the end
of snapping segments using single parent material. To achieve completely symmetric bistable/multi-stable
mechanism, an innovative design strategy is proposed based on interlocking assembly method with multimaterials
and compressed buckled snapping segments for bistable units. Theoretical analysis, numerical simulations
and experimental verifications are used to show completely symmetric bistability/multi-stabilitywith negative
stiffness. The multi-stable mechanical metamaterials have robust shape-reconfigurability and zero
Poisson's ratio with large recoverable deformation. Geometric and material gradients design are carried out to
control deterministic deformation sequencewith rich programmability. Theoretical and numerical results reveal
that tunable 1D to 3D large positive/zero/negative isotropic or anisotropic thermal expansions of single 1D to 3D
multi-stable metamaterials can be achieved, respectively. This work suggests the rational designed metamaterials
with multi-abnormal-index and the potential applications of multi-functional metamaterials.