Adjustable Ultra-Light Mechanical Negative Poisson's Ratio Metamaterials with Multi-Level Dynamic Crushing Effects

Area of Science:

• Materials Science
• Mechanical Engineering
• Metamaterials

Background:

• Mechanical metamaterials (MMs) are engineered materials with unique properties derived from their structure.
• Dynamic crushing effects in MMs are crucial for energy absorption applications, such as impact protection.
• Existing MMs often lack the tunable multi-level crushing characteristics required for adaptive protection.

Purpose of the Study:

• To design and investigate mechanical metamaterials with multi-level dynamic crushing effects (MM-MLs).
• To explore the influence of structural parameters on the mechanical properties and crushing behavior of MM-MLs.
• To demonstrate the potential of MM-MLs for adaptive crushing protection applications.

Main Methods:

• Design of MM-MLs using coordinate transformation and mirror arrays.
• Systematic investigation of the effects of strut/rod ratios, Euler angles, and cell numbers on mechanical properties.
• Analysis of two-level platform stress, rotational motion, collapse compression, and bending during crushing.

Main Results:

• MM-MLs exhibit significant two-level platform stress, with distinct deformation mechanisms in each stage.
• Increasing connecting rod length enhances Poisson's ratio range but reduces platform stress and energy absorption.
• Optimizing Euler angles and increasing cell numbers improve energy absorption capacity and overall performance.

Conclusions:

• MM-MLs demonstrate significant parameter controllability, enabling tailored platform stress, Poisson's ratio, and energy absorption.
• The designed MM-MLs offer functional diversity compared to existing metamaterials.
• This design scheme provides a foundation for developing adaptive crushing protection systems.