Control of Mechanical and Fracture Properties in Two-Phase Materials Reinforced by Continuous, Irregular Networks

Composites with high strength and high fracture resistance are desirable for structural and protective applications. Most composites, however, suffer from poor damage tolerance and are prone to unpredictable fractures. Understanding the behavior of materials with an irregular reinforcement phase offers fundamental guidelines for tailoring their performance. Here, the fracture nucleation and propagation in two phase composites, as a function of the topology of their irregular microstructures is studied. A stochastic algorithm is used to design the polymeric reinforcing network, achieving independent control of topology and geometry of the microstructure. By tuning the local connectivity of isodense tiles and their assembly into larger structures, the mechanical and fracture properties of the architected composites are tailored at the local and global scale. Finally, combining different reinforcing networks into a spatially determined meso-scale assembly, it is demonstrated how the spatial propagation of fracture in architected composite materials can be designed and controlled a priori.