Comparative study of potential pentamodal metamaterials inspired by Bravais lattices

The possibility of designing metamaterials with ad hoc designed elasticity tensors or counter-intuitive mechanical properties, such as a negative Poisson ratio (auxetics), a negative effective bulk modulus or even a negative effective density, has led to the concept of 'mechanical metamaterials'. Due to their special structures, their mechanical properties can be designed to have values that cannot be found in nature which are and adapted for specific applications. A very recent and interesting set of mechanical metamaterials are pentamodes, materials in which five out of six components of the diagonalized elasticity tensor tend to zero, hence somehow imitating the behavior of liquids but being solid. Most studies on pentamodal metamaterials and their applications have been linked to the structure proposed by Milton and Cherkaev in their pioneering work. Here we present the development of a computer-aided design library of potential pentamodal metamaterials, inspired by Bravais lattices, together with a comparative study of their mechanical properties and the eventual verification of pentamodal behavior as a result of simulations based on finite-element methods. We hope this may provide useful information for future designs of devices based on these interesting structures.