Thermal and Mechanical Behaviors of Additively Manufactured Multilevel TPMS Metamaterials With Nonlinear Graded Infill

Triply periodic minimal surface (TPMS) structures offer multifunctional potential. We propose a novel temperature‐guided multilevel TPMS design by infilling Diamond cells into an IWP framework with three spatial distributions. Ti6Al4V specimens were fabricated by laser powder bed fusion. Their transient thermal responses and room‐temperature quasi‐static compressive behaviors were evaluated separately through experiments and finite element simulations. These structures reduced top‐surface temperature by up to 80 °C versus primary IWP structures. In particular, the nonlinear graded configuration produced the lowest top‐surface temperature under the prescribed 300 s heating protocol, indicating delayed through‐thickness heat transfer. The separate thermal and mechanical assessments reveal a geometry‐mediated trade‐off between transient thermal‐shielding performance and compressive response. Although the temperature‐guided morphological heterogeneity reduces the elastic modulus, yield strength, and ultimate compressive strength, it disrupts coplanar stress concentration and promotes a more progressive 45° shear deformation mode, resulting in smoother post‐yield plateau responses. Therefore, the mechanical benefit of the multilevel configurations lies in their modified deformation mode and reduced stress oscillation rather than in improved overall load‐bearing strength or mechanical robustness. This study provides a field‐guided design strategy for load‐bearing and energy‐absorbing thermal‐protection lattices requiring delayed heat penetration and stable progressive deformation.