Crystallography-inspired hierarchical multiscale mechanical metamaterials.

Area of Science:

• Materials Science
• Mechanical Engineering
• Nanotechnology

Background:

• Architected metamaterials offer unique mechanical properties through tailored topologies.
• Advances at micro-, meso-, and macroscales are plateauing, necessitating nanoscale exploration.
• Surface and size effects are critical at the nanoscale for multiphysics performance.

Purpose of the Study:

• To systematically explore the mechanical response of nickel-based nano-architected metamaterials using molecular dynamics simulations.
• To demonstrate the tunability of mechanical properties (elastic moduli, strength, Poisson's ratio) via nano-architecture design.
• To introduce a crystallography-inspired design paradigm for mechanical metamaterials and provide scalable guidelines.

Main Methods:

• Molecular dynamics simulations of nickel-based nano-architected metamaterials.
• Variation of topology, relative density, crystallinity, and grain size.
• 3D printing and experimental characterization of hierarchical polymeric metamaterials.

Main Results:

• Nano-architected metamaterials exhibit tunable elastic moduli, strength, and Poisson's ratio.
• Proposed nano-architected materials outperform existing ones at similar densities.
• Nanoscale free surfaces promote dislocation nucleation but inhibit propagation, increasing flow stress.
• Hierarchical polymeric metamaterials show topology-dependent stiffness, strength, ductility, and toughness.

Conclusions:

• Rational nano-architecture design enables significant improvements in mechanical metamaterials.
• Nanoscale topology-driven designs are highly effective for enhancing material performance.
• A crystallography-inspired approach provides a scalable paradigm for designing advanced mechanical metamaterials across length scales.