Coupling Chiral Cuboids with Wholly Auxetic Response.

Area of Science:

• Materials Science
• Mechanical Engineering
• Metamaterials

Background:

• Auxetic materials exhibit unique mechanical properties like high impact resistance and energy absorption.
• Most current auxetic materials are 2D and display half-auxetic behavior (negative Poisson's ratio under tension or compression only).

Purpose of the Study:

• To introduce novel three-dimensional (3D) auxetic mechanical metamaterials named coupling chiral cuboids.
• To demonstrate the capability of these 3D structures to achieve a negative Poisson's ratio under both tensile and compressive forces.

Main Methods:

• Experimental validation
• Theoretical analysis
• Numerical simulations
• Parametric studies on structural parameters

Main Results:

• The proposed coupling chiral cuboids exhibit a wholly auxetic response (negative Poisson's ratio under both tension and compression).
• Elastic modulus and Poisson's ratio can be tuned by altering the thickness of Z-shaped ligaments, enabling sign-switching.
• Application as inner cores for sandwich panels demonstrated a 49.3% enhancement in energy absorption compared to solid materials.

Conclusions:

• Novel 3D auxetic metamaterials (coupling chiral cuboids) have been successfully designed and validated.
• These materials offer tunable mechanical properties and enhanced energy absorption capabilities.
• The coupling chiral cuboids show significant potential for impact-resistant applications, particularly in sandwich panels.