Figure 8.

A basic model for evaluating local deformations under anisotropic stress. Let $v_f$ denote the fixed vertices at the end of the hexagonal cell array, marked by black-coloured points. The angle $\theta$ indicates the top/bottom angles that can convert hexagonal cells into rectangular shapes. The hexagon is changing its angle owing to a uniform anisotropic stress [52]. Blue arrows in (b) represent the forces applied at each vertex. The blue hexagon in (c) illustrates the change in shape in response to the applied stress.