UC Berkeley

Architected materials are considered the state of the art of engineering ingenuity. Specifically, mechanical metamaterials have been accentuated due to their unconventional and augmented responses. They have been gingerly investigated under the context of ultralight-ultrastiff structures for aerospace applications, tailored buckling mechanisms for energy storage, soft robotics and controlled wave propagation and designed anisotropy for tissue engineering.

Albeit the plethora of remarkable results promulgating this subject, the analysis of architected materials has many questions that need to be addressed. There is no rigorous explanation for the selection of specific 3D designs that have been thoroughly utilized in the literature (regarding the selection of specific design variables and cost functions). Consequently, in practice specific structures are repeatedly used, without any explanation whether further search of the design space could not provide a substantially improved result. Therefore, the lack of understanding of the design space and the inherent physical phenomena has not elucidated the tools to obtain a globally optimal design. Thus, tailoring mechanical metamaterials is extremely arduous and has led to an obstacle in the progress of this field.

This thesis aims to provide an analysis for the design of architected materials by illuminating the physical mechanisms and how to model and optimize such problems. The structure of this thesis is comprised of two main themes. The first method aims to control the mechanical performance through interconnected beam members that enhance the densification of the structure and impede catastrophic failure. The second method is related to geometrical defects that dictate the localized failure and anisotropic behavior. Furthermore, the optimization of specific design examples will be presented, employing low computational power for large design spaces and demonstrate how such design problems can be addressed, setting the framework for the systematic design and characterization of architected materials.