Fibroporous design for tunable stiffness anisotropy in additively manufactured cellular structures

Controlling elastic anisotropy is essential in architected materials that must exhibit direction-dependent stiffness while retaining open geometries for multifunctional performance. Most existing approaches, however, achieve anisotropy through geometric modification, coupling stiffness to other geometry-dependent functions and thereby constraining multifunctional design. Building on our prior demonstration of fibroporous architectures, this work presents a systematic methodology for tailoring stiffness anisotropy in cellular materials without redesigning the base scaffold geometry. Continuous fiber layers—slender bridging struts of the same base material—are embedded within the intrinsic void space of porous lattice structure, where their orientation and distribution act as geometric reinforcement pathways that reorient deformation mechanisms from bending- to stretching-dominated modes, enabling deterministic control of the effective stiffness tensor. The methodology is validated computationally and experimentally, with numerical and experimental results showing consistent directional stiffening trends despite process-induced variability. Because the host scaffold geometry and its continuous surface characteristics are preserved throughout, the approach decouples directional stiffness control from the design of the cellular architecture itself. This establishes a scalable and manufacturable route toward architected materials with tailored mechanical anisotropy within fixed geometric architectures.