Figure 4. Reversible buckling of a bent AG tubular arm.

(a) Tube in the undeformed state; (b) the tube has started to buckle (position indicated by the circle); (c) tube heavily buckled with its stiffness dramatically decreased; (d) the tube recovered elastically its original shape. (e) FEM simulation derived curve (blue) and the analytical one (red) determined from the buckling-hinge model are reported. The shape of the buckling-hinge cross section at different stages from simulation and its prediction from analytical calculations are depicted. The estimated buckling-hinge parameter is γ=0.33, note that the corresponding value determined for buckling at the tetrapod central joint was γ=0.44.