The waves of damage in elastic–plastic lattices with waiting links: Design and simulation

We consider protective structures with elastic–plastic links of a special morphology. The links are bistable. They are designed to arrest the development of localized damage (a neck) in a link, and initiate the damage in another sequential link instead. A wave of “partial damage” propagates through the chain, as all the links develop necks but do not fail. A three-dimensional finite element analysis is used to compute the force–elongation relation for the bistable link. Another numerical procedure analyzes the dynamics of a chain or a lattice undergoing a collision with a heavy projectile. The procedure describes the non-linear waves, determines the places of failure and the critical loading conditions. The bistable chain is compared to the chain of conventional links of the same length, mass, and material. When subjected to an impact, the structure absorbs several times more energy than a conventional structure. The bistability leads to an unexpected result: The maximal absorbed energy in the bistable chain is proportional to its volume, not to the cross-section as in the conventional chain. The bistable chain is capable of withstanding a collision with a mass having kinetic energy several times greater. Even when the bistable chain breaks it effectively reduces the speed of the projectile.