Session: 03-09-02: Materials for Extreme Environments

Paper Number: 190274

190274 - Computational Optimization and Uncertainty Quantification of Additively Manufactured Mechanical Metamaterials 

Lattice structures demonstrate considerable promise in enhancing the efficiency of landing systems for space missions due to their distinctive mechanical properties, lightweight characteristics, and adaptability. However, accurately modeling their behavior under complex loading conditions remains computationally expensive, particularly when large lattices are represented using solid-element finite element models. Although NASA has made substantial progress in the development and testing of additively manufactured lattice structures, critical knowledge gaps remain in optimizing these systems with respect to manufacturing-induced imperfections and free-surface orientation effects, both of which significantly influence structural performance.

This work presents the development and validation of a comprehensive computational framework for the analysis and optimization of additively manufactured lattice structures. The framework integrates the finite element method with truss elements, limit analysis, and Monte Carlo simulation to efficiently capture elastic behavior, failure modes, and uncertainty propagation. The primary structure investigated is the stretching-dominated octet-truss lattice.

The study was conducted in three phases. The first phase focused on performance-driven design optimization under compressive loading, with design variables including unit cell count, surface orientation, and strut aspect ratios. This phase involved extensive uniaxial compression testing, generating experimental data used to validate the computational models.

The second phase quantified the influence of geometric and material uncertainties including variations in strut cross-sectional area and bulk material yield strength on effective elastic modulus, yield stress, and max stress response. Simulation accuracy was assessed through comparison of predicted stress–strain curves with experimental data, commercial finite element software for experimentally tested configurations, and analytical solutions found in literature for known loading cases.

Following validation, the third phase investigated scaling effects and failure progression by examining trends in strut failure patterns under various loading conditions as the number of unit cells in a finite lattice structure increased.

The proposed framework significantly reduces computational cost relative to solid-element models while enabling robust performance prediction under uncertainty. These capabilities support accelerated design, improved reliability, and more efficient fabrication of lightweight lattice structures for future space applications.

Presenting Author: Lucas Stevenson University of Kentucky

Presenting Author Biography: Lucas Stevenson is a graduate research assistant in Aerospace Engineering at the University of Kentucky, where he is pursuing an M.S. under the advisement of Dr. Xingsheng Sun. His research focuses on the experimental characterization and computational modeling of additively manufactured lattice structures for lightweight aerospace applications. Supported by the NASA Kentucky Space Grant Consortium, his work integrates truss-based finite element modeling, limit analysis, and experimental validation to investigate the effects of free-surface orientation and manufacturing variability on octet-truss lattice performance. Stevenson earned dual bachelor’s degrees in Aerospace Engineering and Mathematics, graduating summa cum laude. He previously served as President of the UK rocketry team, leading the design and manufacturing of competition rockets and payload systems including a CubeSat experiment that tested 3D printed lattice structures as shock absorption devices at high g-load events during flight. His broader interests include structural mechanics and lightweight space system design.