Auxetic Metamaterials with Structurally Programmed Reconfigurability

Low density engineering materials capable of reacting to mechanical stimuli in a manner programmed by their structural architecture can improve design of shock and impact resistant or tunable acoustic damping structures, robust actuators, and adaptable heat insulators.Similarly to computers, structural programming translates the human developed algorithm into a string of structural commands obeying syntax enabling to perform the desired task. The structural coding of commands converts the materials programming language (MPL) into a low-level language understandable by the executing architected structure. While constitutive materials capable of carrying the basic structural information already exist, designing the source code, commands compiler, assembler, and linker for the MPL remains a foundational challenge. Here, we outline the strategy for developing the source code for simple MPL commands using functional polymer nanocomposites as the units of structural information (USIs). USIs are spatially organized within simple geometrical elements of the re-entrant auxetic unit cell constituting the basic storage units of structural information (SUSIs). SUSIs are combined in a library of bending eigenmodes and rotations forming the structural source code enabling to program simple MPL commands. Primitive algorithms are developed, and simple commands are structurally coded at the auxetic unit cell array and lattice levels to achieve desired stimuli induced reconfigurations of the auxetic structure. Finally, multi-port FDM fabrication process is employed for physically compiling, assembling, and linking the structural commands into the auxetic structure with structurally pre-programmed system level response.