Progressive Reinforcing of Re-entrant Auxetic Structures by Direct Polyurethane Foaming within Unit Cells

Nisa Calaner, Erden Burak Kivandik, Eyuphan Kucukkalfa, Kaan Yildiz

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Mechanical metamaterials having a negative Poisson ratio, called auxetic metamaterials, exhibit high specific strength and excellent energy absorption capacity, allowing them to be implemented as potential energy absorbers and vibration dampers in aerospace structures. In addition to their intrinsic and promising features, the structural integrity and energy absorption capability of auxetic structures can be enhanced by polymeric foam reinforcement. Rigid polyurethane (PU) foams, a family of polymeric foams, have been frequently utilized in foam-filling studies of lattice structures, owing to their ease of manufacturing and tailorability via process optimization and micro-/nano- reinforcements. Among the myriad of reinforcement types for PU foams, elastomeric nanoparticles (ENPs) demonstrate a great potential to improve the mechanical and viscoelastic properties of the foams. In addition, achieving direct foaming within the unit cells of auxetic structures offers a more effective procedure as opposed to manual placement of foams into the vacancies since greater adhesion and structural integrity are assured because of the high-temperature foaming process. In this work, PU foams were reinforced with ENPs using various weight fractions and subjected to cyclic compression tests. Following that, re-entrant auxetic structures were filled with neat and ENP-reinforced PU foams and cyclic compression tests were carried out to determine the influence of ENPs on mechanical properties and energy absorption capabilities of auxetic structures.

Original languageEnglish
Title of host publicationAIAA SciTech Forum and Exposition, 2024
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
ISBN (Print)9781624107115
Publication statusPublished - 2024
EventAIAA SciTech Forum and Exposition, 2024 - Orlando, United States
Duration: 8 Jan 202412 Jan 2024

Publication series

NameAIAA SciTech Forum and Exposition, 2024


ConferenceAIAA SciTech Forum and Exposition, 2024
Country/TerritoryUnited States

Bibliographical note

Publisher Copyright:
© 2024 by The MITRE Corporation. Published by the American Institute of Aeronautics and Astronautics, Inc.


Dive into the research topics of 'Progressive Reinforcing of Re-entrant Auxetic Structures by Direct Polyurethane Foaming within Unit Cells'. Together they form a unique fingerprint.

Cite this