Stress Steering and Stiffness Tuning in Modular Topological Maxwell Lattices

Topological mechanical metamaterials (TMMs) are architected materials whose structure imparts novel, robust mechanical properties from mechanical topological states. Existing TMM-based stress control has largely focused on a single uniaxial loading case. In this study, we show how to enable TMMs that forenable robust stress control under diverse loading conditions and extend simple lattice geometries into fully modular materials. The underlying mechanism is the excitation of states of self-stress (SSSs) along stress interfaces via the interaction with zero modes (ZM) on adjacent soft interfaces; this coupling is sensitive to the spacing between the SSS and ZM interfaces. We identify two types of ZM–SSS influence: first-order excitation and second-order excitation. Both numerical and experimental results show that our modular topological Maxwell lattice not only concentrates stress under diverse loading scenarios, but also creates tortuous crack paths that deliver superior fracture toughness compared with a single domain lattice.