Design of Functionally Graded Lightweight Metamaterials Based on Triply Periodic Minimal Surface Lattices for Improved Impact Loading

Abstract

Due to recent advancements in additive manufacturing technologies, lattice structures, particularly those with triply periodic minimal surface characteristics, are gaining popularity across various engineering domains. Due to their unique deformation behavior, these structures offer a combination of lightweight and robust mechanical properties. However, each lattice topology is tailored to specific loading conditions, necessitating the development of lattice designs capable of fulfilling multiple functions simultaneously. By functionally grading minimal surface sheet-based lattice topologies using techniques such as hybridization, varying cell sizes, adjusting relative densities, altering periodicity, or combining these approaches, achieving the desired multifunctional mechanical behavior is possible. This thesis represents a pioneering effort in exploring multiple topology-functional gradation techniques to design minimal surface lattice structures that address real-world challenges related to enhancing the flexural, compressive, and impact performance of lightweight materials and sandwich structures. Implicit design strategies are employed in creating these innovative lattice designs, fabricated using the laser powder bed fusion process and tested alongside conventional ones. The thesis also emphasizes developing computational models capable of accurately simulating experimental outcomes, thereby minimizing costs and overcoming barriers in computational modeling science. The key findings of this thesis underscore the significance of strategically combining relative density gradation with topology hybridization to regulate deformation behavior in lattice materials and sandwich structures subjected to four-point bend loading, compression loading, and impact loading. These combinations lead to noteworthy enhancements in the mechanical performance of these materials and structures. Furthermore, this thesis delves deeper by introducing, for the first time, the concept of grading periodic orientation and randomness within a single lattice topology. This innovative approach aims to manage mechanical anisotropy in lattice-sandwich composites, thereby improving impact loading performance without altering the overall relative density. The efficacy of this approach is validated through a combination of experiments and simulations.

Date of Award	19 Dec 2023
Original language	American English
Supervisor	IMAD Barsoum (Supervisor)