Date Approved

7-7-2021

Embargo Period

7-8-2021

Document Type

Thesis

Degree Name

M.S. Mechanical Engineering

Department

Mechanical Engineering

College

Henry M. Rowan College of Engineering

Advisor

Behrad Koohbor, Ph.D.

Committee Member 1

Chen Shen, Ph.D.

Committee Member 2

Nand Singh, Ph.D.

Keywords

ARCHITECTED MATERIALS, DENSITY GRADATION, FUNCTIONALLY GRADED MATERIALS, HONEYCOMBS, OPTIMIZATION, VIRTUAL EXPERIMENT

Subject(s)

Honeycomb structures

Disciplines

Materials Science and Engineering | Mechanical Engineering

Abstract

Density gradation has been analytically and experimentally proven to enhance the load-bearing and energy absorption efficiency of cellular solids. This research focuses on the analytical optimization (by virtual experiments) of polymeric honeycomb structures made from flexible thermoplastics to achieve density-graded structures with desired mechanical properties. The global stress-strain curves of single-density honeycomb structures are used as input to an analytical model that enables the characterization of the constitutive response of density-graded hexagonal honeycombs with discrete and continuous gradations and for various gradients. The stress-strain outputs are used to calculate the specific energy absorption, efficiency, and ideality metrics for all density-graded structures. The analytical results are shown to be in good agreement with previous experimental measurements. The findings of this research suggest that the choice of an optimal gradient depends on the specific application and design criteria. For example, graded structures wherein low-density layers are dominant are shown to outperform high density uniform honeycombs in terms of specific energy absorption capacity while possessing higher strength compared with low density uniform structures.

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