Stiffness and Strength Enhancement of Variable-Thickness Triply Periodic Minimal Surface Shell Lattices via Stress-Feedback-Driven Design

Triply periodic minimal surface (TPMS) shell lattices combine high mechanical efficiency with an open-cell topology, yet their stiffness and strength remain well below theoretical upper bounds, leaving considerable room for further enhancement. This study develops a stress-feedback-driven continuous variable-thickness method for simultaneous stiffness and strength enhancement of TPMS shell lattices. Finite-element analyses provide nodal von Mises stresses that are mapped into relaxed thickness updates; spatial filtering and target-volume normalization maintain a smooth thickness field and constant material volume. The method thickens highly loaded regions and thins underutilized regions while keeping the mid-surface geometry unchanged. Across a relative density (RD) range of 5–20% and a maximum-to-minimum thickness-ratio of 100, the effective Young’s modulus and yield strength of N14 shell lattices can be increased by up to 46.39% and 58.82%, respectively. With the thickness ratio restricted to 10, the corresponding maximum enhancementremain 30.90% and 46.75%. The improvement results from transferring material toward existing load paths and increasing the fraction of the shell that participates effectively in load transfer. The proposed method provides a numerically efficient route for designing high-performance lightweight shell lattices. The results obtained with a large thickness-ratio limit represent numerical performance potential and may include locally ultrathin regions, whereas the moderate-contrast thickness fields are manufacturing-oriented numerical candidates that consider the fabrication constraints.