Soft network materials with isotropic negative Poisson's ratios over large strains

Area of Science:

• Materials Science and Engineering
• Mechanical Engineering
• Biomedical Engineering

Background:

• Auxetic materials exhibit a negative Poisson's ratio (NPR), expanding laterally when stretched.
• Existing auxetic materials face challenges in achieving isotropic NPR over large strain ranges, limiting biomedical applications.
• Artificial auxetic materials are crucial for innovations in diverse engineering fields.

Purpose of the Study:

• To introduce deterministic design routes for soft architected materials with tunable, isotropic negative Poisson's ratios.
• To enable precise tailoring of Poisson's ratio from -1 to 1 over large tunable strain ranges (0% to ~90%).
• To address the challenge of achieving isotropic NPR over large strains for advanced applications.

Main Methods:

• Utilized network construction in a periodic lattice topology with zigzag microstructures.
• Combined experimental and theoretical studies across various network topologies.
• Employed quantitative mechanics modeling for infinitesimal and finite deformations to develop a design algorithm.

Main Results:

• Demonstrated a rigorous design algorithm for achieving target Poisson ratios over desired strain ranges.
• Successfully created architected materials with precisely controlled isotropic negative Poisson's ratios.
• Showcased tunable strain ranges from 0% to approximately 90%.

Conclusions:

• Introduced a versatile design strategy for auxetic materials with highly controllable and isotropic negative Poisson's ratios.
• Highlighted potential applications in artificial skin mimicking biological properties and novel cylindrical structures.
• The developed methodology offers broad utility for engineering advanced materials with tailored mechanical responses.