Isotropic conformal minimal surface generation strategies for additively manufactured metamaterials

Triply periodic minimal surface (TPMS) lattice infills offer high stiffness-to-weight ratios but are inherently non-conformal when embedded within complex three-dimensional components, which can reduce structural efficiency under realistic boundary conditions. This work introduces the Isotropic Conformal Minimal Surface (ICMS) for generating shell-based metamaterial infills that conform exactly to arbitrary design domains while exhibiting near-isotropic elastic behaviour. Two novel ICMS topologies are proposed and benchmarked against conventional cubic TPMS infills using finite element analysis. A shell-based formulation enables stiffness-driven size optimisation through thickness variation under a global volume constraint. The mechanical performance of the proposed approach is demonstrated using two case studies: a femur-shaped structure and a bearing bracket. In the femur example, ICMS infills achieve lower compliance than TPMS benchmarks despite lower intrinsic bulk stiffness, owing to improved geometric conformity and alignment with dominant load paths. In the bearing bracket example, functional grading of ICMS cell size based on stress-informed surface seeding leads to reduced compliance and more homogeneous stress distributions, which are quantified using Weibull statistics. The results show that conformal meshing can offset intrinsic stiffness disadvantages at the unit cell level, yielding mechanically superior component-level performance. ICMS provides a scalable, additive manufacturing compatible framework for conformal lattice design and stiffness optimisation in complex geometries. • Introduces an isotropic conformal meshing strategy for lattice infill generation • Demonstrates stiffness gains from geometric conformity over cubic TPMS infills • Enables efficient shell-based size optimisation under global volume constraints • Shows improved stress uniformity via functionally graded ICMS cell sizing • Validated on femur and bearing bracket geometries using finite element analysis