Light-weight shell-lattice metamaterials for mechanical shock absorption

Absorbing mechanical shocks and vibration energy is crucial in industrial, domestic and medical applications. Very often, systems (such as hydraulic cylinders) or structures (such as helmets) are used to achieve energy absorption or protection from impacts or periodic vibrations. In this respect, mechanical metamaterials have received much attention in recent years due to their extraordinary mechanical properties, including outstanding specific stiffness and strength, and energy absorption. Here, we design a stretching-dominated mechanical metamaterial that can absorb very large energies while retaining a low density. In this study, a few examples of metamaterials are considered and we show that a new class of shell lattice (SL) metamaterials has the best mechanical properties for shock absorption they are ultrastiff, ultrastrong, and possess high specific energy absorption at low relative density.