Bio-inspired beam lattice materials with sacrificial bonds

We consider the controlled non-localized brittle fracture of a periodic beam-lattice subjected to tensile loading. The specific lattice architecture ensures overstress of a periodic group of sacrificial beam elements prior to the macrocrack appearance. Thus, at the initial stage of damage, the lattice material implements the borrowed from nature ”partially break but not fail” paradigm. Consequently, it becomes less stiff and absorbs energy, while still remaining intact. We find several two-dimensional lattices characterized by this feature and examine their elastic and fracture behavior. For the lattices with triangular cells it is found that the anisotropic lattice with the beams of uniform thickness and different lengths is a better energy absorber than the isotropic one where the beam elements of the same length have different thicknesses. Moreover, both configurations are inferior in this regard to the bone-microstructure inspired lattice with rectangular cells.