Extended Data Fig. 1: Buckling behaviours of the unit cell with elastoplastic material.
From: Harnessing plasticity in sequential metamaterials for ideal shock absorption
a, Sketch of a buckling unit cell. b–d, Three regimes of buckling are described by force, deflection and plastic strain. The normalized force F/Fy is used to determine the stiffness at the buckling point and the postbuckling stiffness S (black curve), the normalized deflection w/ℓ is used to determine the buckling point (blue curve) and the plastic strain εp is used to determine the onset of plasticity at the ligaments (red curve). The blue shading denotes the buckled regime, the salmon filling denotes the regime of plastic deformations and the magenta filling denotes the combined regime with both buckling and plastic deformations. b, Elastic buckling. c, Plastic buckling. d, Yield buckling. e, Postbuckling stiffness S versus aspect ratio of the unit cell t/ℓ and ratio between yield stress and Young’s modulus σy/E. The red triangles denote the yield-buckling regime defined by S < 0 and Fsc < Fcr.
