Engineering the crack path in lattice cellular materials through bio-inspired micro-structural alterations

A computational study on the fracture behaviour of bio-inspired finite-size lattice configurations is performed in this work. The study draws inspiration from recent investigations aimed at increasing the fracture energy of some materials through small modifications of their microstructure. The main question here is whether it is possible, to some extent, to engineer the crack path in metallic cellular materials through such small micro-structural modifications and how to quantify the effect of alternative strategies. Nature provides several examples of strategies used to delay or arrest damage and crack propagation. One striking example is given by the micro-architecture of several kinds of wood, in which the crack propagation through a lignin cellular matrix is affected by density variations typical of the seasonal alternation between early-wood and late-wood and by the presence of sap channels. In this study, the effects on crack propagations induced by micro-structure alterations inspired by density variations and sap channels in wood are computationally investigated and some figures of merit are defined to assess the effect on the energy absorbed by alternative solutions. In an age in which tight control of the microarchitecture can be achieved, e.g. through high-resolution 3D printing, it is of interest to investigate whether, starting from a baseline cellular architecture, it is possible to achieve superior material performance by smart modifications of the microarchitecture.