Multistable shape-shifting surfaces
Multistable shape-shifting surfaces that retain their effectiveness as physical barriers while undergoing changes in shape and that can remain stable in the various shapes. The shape changes include any motion that makes the surface more effective at performing its function, such as expansion, shrinkage, twisting, encircling, wiggling, swallowing or constricting. The shape-shifting surfaces include tiled arrays of polygonal cells, each cell including specifically-designed compliant flexures attached to specifically-shaped overlapping thin plates or shells. The surfaces remain stable by leveraging them during deformation to an extent that they cannot spontaneously return to the unstressed shape. Applications for such surfaces include micro-scale cellular engineering and macro-scale biomedical applications, recreational uses, national security, and environmental protection.
1. A shape shifting surface, comprising:
at least one unit cell including a plurality of layered, adjacent, overlapping compliant side members;
said side members including compliant flexures and flat plate segments, said compliant flexures including multistable compliant mechanisms;
said compliant flexures including joints and nodes that have a first position and a second position;
said first position and said second position of said nodes being substantially within a line of action;
said compliant side members being joined at said nodes and being pivotal about said nodes; and
said compliant side members forming a contiguous line of sight barrier in said first position and in said second position.
2. A shape shifting surface as in claim 1 , further comprising:
said at least one unit cell having a quadrilateral shape and including four adjacent compliant side members.
3. A shape shifting surface as in claim 1 , further comprising:
said second position of said nodes being disposed in abutting relation to said plate segments.
4. A shape shifting surface as in claim 1 , further comprising:
each side member of said compliant side members including a first node positioned at a free end of a compliant flexure selected from said compliant flexures and a second node at one corner of said plate segment, said second node being substantially within said line of action of said first node.
5. A shape shifting surface as in claim 1 , further comprising:
said shape shifting surface maintaining a contiguous line of sight barrier when deforming in response to application of a sufficient external force; and
said deformation shifting said compliant flexures from said first position to said second position.
6. A shape shifting surface as in claim 5 , further comprising:
said shape shifting surface returning to said first position when said application of said sufficient external force is released.
7. A shape shifting surface as in claim 5 , further comprising:
said first position having substantial stability so that said shape shifting surface does not spontaneously shift to said second position; and
said second position having substantial stability so that said shape shifting surface does not spontaneously shift to said first position.
8. A shape shifting surface as in claim 7 , further comprising:
said first position being an expanded position so that said shape shifting surface has said substantial stability in said expanded position; and
said second position being a compressed position so that said shape shifting surface has said substantial stability in said compressed position.
9. A shape shifting surface as in claim 7 , further comprising:
all edges of said shape shifting surface remaining substantially within the boundary of said shape shifting surface when said shape shifting surface is in said first position; and
all edges of said shape shifting surface remaining substantially within the boundary of said shape shifting surface when said shape shifting surface is in said second position.
10. A shape shifting surface as in claim 8 , further comprising:
said deformation shifting said shape shifting surface from said first position to a third position;
said deformation shifting said shape shifting surface from said second position to said third position;
said third position being a shearing position.
11. A shape shifting polygon, comprising:
a first polygonal cell including a first plurality of unit cells;
said first plurality of unit cells including layered, adjacent, overlapping compliant side members coupled to retain their effectiveness as physical barriers while undergoing changes in shape, said side members including compliant flexures and flat plate segments, said compliant flexures including multistable compliant mechanisms;
said changes in shape including expansion, shearing, shrinkage, twisting, vibrating, encircling, wiggling, swallowing or constricting;
said shape shifting polygon having more than one position of substantial stability, said more than one position of substantial stability occurring as a result of said changes in shape,
said side members forming a contiguous line of sight barrier in said more than one position of substantial stability.
12. A shape shifting polygon as in claim 11 , further comprising:
said compliant flexures disposed at a free end of said side members.
13. A shape shifting polygon as in claim 11 , further comprising:
said unit cells including an initial planar structure and a final spatial structure;
said more than one position of stability including said initial planar structure and said final spatial structure.
14. A shape shifting polygon as in claim 11 , further comprising:
a second polygonal cell including a second plurality of unit cells;
said second plurality of unit cells including compliant side members coupled to retain their effectiveness as physical barriers while undergoing changes in shape;
said second polygonal cell being coupled to said first polygonal cell.
15. A shape shifting polygon as in claim 14 , further comprising:
said second polygonal cell undergoing said changes in shape independently from said first polygonal cell.
16. A shape shifting polygon as in claim 11 , further comprising:
said first plurality of unit cells being joined to one another by compliant pin connectors.
17. A shape shifting polygon as in claim 11 , further comprising:
a tiled array of polygonal cells including said first polygonal cell.