Role of local response in manipulating the elastic properties of disordered solids by bond removal.

We explore the range over which the elasticity of disordered spring networks can be manipulated by the removal of selected bonds. By taking into account the local response of a bond, we demonstrate that the effectiveness of pruning can be improved so that auxetic (i.e., negative Poisson's ratio) materials can be designed without the formation of cracks even while maintaining the global isotropy of the network. The bulk modulus and shear modulus scale with the number of bonds removed and we estimate the exponents characterizing these power laws. We also find that there are spatial correlation lengths in the change of bulk modulus and shear modulus upon removing different bonds that diverge as the network approaches the isostatic limit where the excess coordination number ΔZ → 0.