Session: 06-10-01: Advanced Manufacturing in Aerospace Engineering

Paper Number: 166164

Biaxial Tension and Compression Mechanical Behavior of a Novel Star Arrowhead
Auxetic Structure 

Auxetic structures exhibit high energy absorption and stiffness to density ratios that makes them applicable to numerous engineering systems. The negative Poisson’s ratio of the auxetic structure enables high performance in energy absorption compared to non-auxetic structures. Many studies have analyzed several hybrid auxetic topologies that combine typical auxetic topologies together. Hybrid auxetic topologies alter the negative Poisson’s ratio and increases the stiffness of the structure. The properties of these auxetic structures have achieved a negative Poisson’s ratio of around -1. However, challenges related to the durability of auxetic structures, as well as maintaining consistent stiffness and flexibility, hinder their integration into industrial applications. Maintaining the negative Poisson’s ratio of auxetic structures over a long period of service at the level of failure strength is crucial for real world applications.  

This research focuses on the biaxial mechanical behavior of a newly developed star arrowhead auxetic structure under different biaxiality ratios. Literature highlights the developments of auxetic structures to achieve high stiffness-to-density ratios using stretch-dominated mechanisms. The combination of various auxetic topologies and material choices can significantly influence the energy absorption and stiffness of these structures without affecting the materials’ integrity. While failure mechanisms and the Poisson's ratio of auxetic unit cells and structures under uniaxial in-plane loads have been explored, the mechanical properties, damage initiation and propagation, evolution of Poisson's ratio, stiffness, and energy absorption capacities of auxetic systems under biaxial tension and compression have not been sufficiently investigated. Literature suggests that under multidirectional stress, auxetic structures can maintain flexibility while retaining their high axial stiffness and energy absorption.  

This study aims to explore the bi-axial tension and compression behavior of a recently developed stretch-dominant star arrowhead auxetic topology that exhibits enhanced ductility under various biaxial load ratios. The research team has created a new topological design that improves the energy dissipation of the star arrowhead auxetic structure. The team will examine the impact of biaxial displacement load conditions on key properties such as the negative Poisson’s ratio, stiffness, ductility, and plasticity. The star arrowhead auxetic structure will be investigated under high extreme loading to determine changes in the structures’ impact resistance and its failure mechanisms under bi-axial load conditions. The authors will present both experimental investigations and numerical analyses of the auxetic unit cell, focusing on structure failure patterns and envelop functions under biaxial loads. Additionally, the research team will investigate the relationship between Poisson's ratio and failure mechanisms at the micro-scale using scanning electron microscopy and digital imaging techniques.

Presenting Author: Eric Lee California Polytechnic State University

Presenting Author Biography: Eric Lee is an undergraduate student in Mechanical Engineering at California Polytechnic State University San Luis Obispo. His research focuses on auxetic structures with an emphasis on the response to bi-axial tension and compression. At IMECE, he will present on the mechanical behavior of a novel auxetic structure under biaxial loading conditions.

Authors:

Eric Lee California Polytechnic State University
Jose Villegas Hernandez Arizona State University
Masoud Yekanifard California Polytechnic State University San Luis Obispo