Rhombic nested architected materials: achieving isotropy with tunable anisotropy

Architected materials offer exceptional specific stiffness, strength, and energy absorption, yet achieving mechanical isotropy under complex multiaxial loading remains a critical challenge. Here, we introduce rhombic nested lattices (RNLs)—a novel class of bioinspired cellular architectures that provide unprecedented control over both isotropic and anisotropic mechanical responses. By systematically varying nesting order, orientation, fractal hierarchy, and enforcing cubic symmetry, we design nine mono-rhombic and forty poly-rhombic configurations. Numerical homogenization reveals that poly-RNLs exhibit near-perfect isotropy, while mono-RNLs enable tunable anisotropy—greatly expanding the design space and outperforming existing lattice materials. Representative stretch-dominant mono-RNLs, fabricated via selective laser melting at 30% relative density, demonstrate superior compressive strength, energy absorption, and damage tolerance compared to shear-dominant counterparts. A nonlinear finite element model, calibrated with experimental data, accurately captures their crushing response, validating the robustness of the design framework and offering a predictive capability. By integrating bioinspired topology, additive manufacturing, and predictive simulation, RNLs establish a versatile and scalable platform for next-generation architected materials with transformative potential in aerospace, biomedical, and protective applications.