Date of Award
Spring 2026
Document Type
Open Access Dissertation
Department
Mechanical Engineering
First Advisor
Andrew J Gross
Abstract
Architected cellular materials ofer a powerful approach for achieving lightweight structures with mechanical properties that cannot be obtained through parent-material selection alone. By tailoring topology, geometry, and hierarchy, cellular architectures can be designed to enhance stifness and strength at low relative density while control- ling instability and stress localization. This dissertation investigates the mechanics and optimization of architected cellular materials with a focus on improving stifness and strength through complementary design strategies spanning exploiting parent materials latent properties, introducing multiscale hierarchy, and optimization of ge- ometry.
The frst part of the dissertation develops buoyant architected materials (BAMs) for extreme hydrostatic pressure environments, motivated by long-duration Venus exploration. Theoretical performance limits are established for ceramic truss lattices subjected to high confnement, and the pressure-sensitive shear strength of ceramics is exploited to achieve strength enhancements beyond classical scaling relations. Finite element modeling and shape optimization are used to generate Kelvin-based lattice geometries that mitigate buckling and redistribute stresses toward favorable confned states while maintaining ultralow relative density and thermal conductivity.
The second part introduces Warren truss-inspired hierarchical beams as mechan- ically efcient building blocks for hierarchical truss lattices. Analytical models for stifness and buckling are developed and validated with fnite element simulations, and the hierarchical beams are integrated into second-order Kelvin and octet lat- tices. The results demonstrate that hierarchy can improve stifness and strength, vparticularly in regimes governed by elastic instability.
The third and fourth parts focus on two-dimensional architectures. First, the infu- ence of nodal fllets on the stifness, yield strength, and buckling strength of equilateral triangular lattices is quantifed using analytical and numerical modeling, producing design maps that identify optimal nodal geometries. Next, the optimized stretching- dominated triangular lattice is leveraged as a lower-order hierarchical building block within a bending-dominated honeycomb architecture. These hierarchical honeycombs are optimized using surrogate-based multi-objective optimization and validated exper- imentally, demonstrating substantial improvements in stifness and strength relative to conventional honeycombs at equivalent relative density. Overall, this dissertation provides mechanics-based design tools and optimization frameworks for architected cellular materials across multiple length scales.
Rights
© 2026, Fakhreddin Emami
Recommended Citation
Emami, F.(2026). Mechanics and Optimization of Architected Cellular Materials. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/8862