Fig. 1.

Torsion-bending antagonistic bistable design. (A) Schematic of torsion-bending antagonistic bistable design. It is built by attaching 2 living hinges in between the frames of a prestretched LET joint. The prestretch yields bending deflection in the 4 LET beams, while the rotation of the LET joint produces torsional deflection. (B) A strain energy barrier. The maximum position (I) is produced through prestretch, and the strain energy drops when the joint rotates in either direction, generating 2 local minimum positions (II and III). The 2 local minimum positions on the total strain energy curve correspond to 2 stable states while the maximum position to unstable equilibrium state of the design. (C) Strain energy curves of the LET beams due to bending and torsion.