Auxetic Two‐Phase Chevron Mechanical Metamaterial

This investigation explores novel two‐phase chevron mechanical metamaterials that exhibit auxetic properties. Unlike traditional foam‐like cellular or porous auxetic materials, these designs are composed of chevron patterned layers embedded in anisotropic matrix. This innovation design allows for auxeticity in two orthogonal in‐plane directions (bi‐auxeticity) or in all in‐plane directions (complete auxeticity), providing not only a general strategy but also detailed guidelines for designing non‐porous auxetic mechanical metamaterials with tunable auxetic behaviors. One goal of this work is to explore the mechanical behavior, specifically effective stiffness and Poisson’s ratio, of these new designs and to identify the design space for auxetic behavior using numerical and experimental methods. Systematic finite element (FE) simulations were conducted using ABAQUS and Python scripts to quantify effective stiffness and Poisson’s ratio within a small strain range. To validate the numerical predictions, three representative designs were selected and fabricated via multi‐material polymer jetting. Uniaxial tension experiments were conducted on these specimens. Design spaces for non‐auxeticity, partial‐auxeticity, and complete auxeticity were identified through an integrated numerical approach. Theoretical criteria for determining the completeness of auxeticity were proposed and verified via FE simulations. This article is protected by copyright. All rights reserved.