Fig. 6
From: Mathematical modeling of auxetic systems: bridging the gap between analytical models and observation
To-scale representation of the hinging honeycombs with h = 2, l = 1 as these are stretched/compressed in the vertical or horizontal direction. Note that systems where θ < 90o cannot be pulled in the horizontal direction past the system where θ = 90o to achieve θ > 90o whilst the systems where θ > 90o cannot be pulled in the horizontal direction past the system where θ = 90o to achieve θ < 90o, i.e. θ = 90o corresponds to a ‘locking conformation’ for pulling in the horizontal direction