Controllable interlocking from irregularity in two-phase composites

Inspired by strong and tough biological materials, we present composite materials with controllable interlocking. The composites feature tessellations of stiff particles connected by a soft matrix, and we control the degree of interlocking through irregularity in particle size, geometry, and arrangement. We generate the composites through stochastic network growth using an average network coordination number. The generated network forms the soft matrix phase of the composites, while the areas enclosed by the network form the stiff reinforcing particles. At low coordination, composites feature highly polydisperse particles with irregular geometries arranged non-periodically. In response to loading, these particles interlock and primarily rotate and deform to accommodate non-uniform kinematic constraints from adjacent particles. In contrast, higher-coordination composites feature more monodisperse particles with uniform geometries, which collectively slide. We quantify how to control the degree of interlocking as a function of coordination number alone, demonstrating how irregularity facilitates bioinspired deformation mechanism control.