Extreme localization of damage in conventional brittle materials is the source of a host of undesirable effects. We show how artificially engineered metamaterials with all brittle constituents can be designed to ensure that every breakable sub-element fails independently. The main role in the proposed design is played by high contrast composite sub-structure with zero-stiffness, furnishing nonlocal stress redistribution. The ability to de-localize cracking in such nominally brittle systems is revealed by the fact that their continuum description is dominated by the gradient (bending) rather than classical (stretching) elasticity. By engineering a crossover from brittle to effectively ductile (quasi-brittle) behavior in prototypical systems of this type, we reveal the structural underpinning behind the difference between fracture and damage.

传统脆性材料中损伤的极端局部化是一系列不良影响的根源。我们展示了如何设计具有所有脆性成分的人工工程超材料，以确保每个易碎的子元素独立失效。拟议设计中的主要作用是由具有零刚度的高对比度复合子结构发挥作用，提供非局部应力重新分布。在这种名义上的脆性系统中去局部化开裂的能力是通过它们的连续描述由梯度（弯曲）而不是经典（拉伸）弹性主导的事实来揭示的。通过在这种类型的原型系统中设计从脆性到有效延性（准脆性）行为的交叉，我们揭示了断裂和损坏之间差异背后的结构基础。