Session: 03-04-01: Emerging Materials Technology I

Paper Number: 106863

106863 - Multifunctional Performance of Nanoengineered Auxetics: 3d Printing, Experiments and Computational and Data-Driven Modeling 

Additive Manufacturing (AM), also known as 3D printing, has rapidly gained importance in recent years, through its various advantages and design freedom compared to traditional manufacturing methods. Driven by engineering industries such as aircraft, automotive and sports etc., the demand for new materials with excellent mechanical and functional properties is consequently increasing with a focus on lightweight cellular materials with high mass-specific stiffness, strength and energy absorbing characteristics. Additionally, unusual properties such as negative Poisson’s ratio, negative stiffness, or negative compressibility are being explored. In this study, a new method for generating 2D cellular structures capable of exhibiting negative Poisson's ratio (i.e. auxetics) is proposed, focusing on the underlying design parameters rather than the final shape. A large number of these smart auxetics were fabricated using carbon black (CB) incorporated polylactic acid (PLA) filaments via fused filament fabrication (FFF). The effects of the design parameters on the mechanical and piezoresistive performance of PLA/CB nanocomposite auxetics under tensile loading were investigated. Finite element modeling and machine learning tools were used to support the experimental results and to explore the vast design space beyond the experimentally realized ones. It was found that the chosen design parameters can significantly influence the mechanical and piezoresistive performance as well as the auxetic behavior. The gauge factor - a measure of change in normalized resistance per unit strain in the elastic regime, was found to scale proportionately with the stiffness of the auxetic structures. Furthermore, by tuning the design parameters, auxetic structures were found to exhibit 23 times increase in elastic stiffness and 35 times increase in gauge factor for the same relative density. The lowest Poisson's ratio measured was -0.74, which demonstrates excellent auxeticity of the proposed auxetic structures. It is believed that such smart auxetic structures, due to their self-sensing capabilities, will gradually be adopted for applications where auxetic deformation is required, enabling in situ monitoring of the structural health of components.

Presenting Author: Johannes Schneider University of Glasgow

Presenting Author Biography: Johannes was awarded a Dipl.-Ing. degree in Mechanical Engineering with a focus on lightweight construction and composites from the Technical University of Dresden, Germany. After graduation, he moved to Abu Dhabi, UAE, to work on additive manufacturing of cellular structures at Khalifa University. He is currently pursuing a PhD at the University of Glasgow, UK, on additively manufactured multifunctional micro-architected cellular composites for biomedical applications with a focus on PEEK nanocomposites.

Authors:

Johannes Schneider University of Glasgow
Kumar Shanmugam University of Glasgow
Vinayak Krishnamurthy Texas A&M University
Ergun Akleman Texas A&M University
Ramakrishna Tipireddy Pacific Northwest National Laboratory
Kai Lupo Texas A&M University
Matthew Ebert Texas A&M University