Fig. 4.

The 2D transition waves. (A) Experimental observations of transition waves propagating through 2D structures (after initialization in the fully open configuration, each transition wave is triggered by a point load applied by the black indenter). Waves are controlled by boundary conditions (e.g., boundary application sites) as well as by defects (e.g., point defects realized by nontransforming open unit cells). Examples show free transition wave propagation in two directions, wave pinning, wave deflection, and rotation. (B) Numerical results obtained from the continuum model are in good agreement with experimental findings (differences stemming mainly from imperfections and size effects).