Soft Mechanical Metamaterials with Transformable Topology Protected by Stress Caching

Area of Science:

• Topological mechanics
• Mechanical metamaterials
• Soft matter physics

Background:

• Maxwell lattices exhibit unique topological states with protected edge behaviors.
• Previous demonstrations of reconfigurable topological mechanics were limited to fixed configurations or mechanical linkages.

Purpose of the Study:

• To introduce a monolithic, transformable topological mechanical metamaterial.
• To enable reversible exploration of topologically distinct phases.
• To demonstrate robustness against defects and stress history.

Main Methods:

• Fabrication of a generalized kagome lattice from a shape memory polymer (SMP).
• Utilizing a kinematic strategy for global transformation and topological state switching.
• Investigating the role of SMP phase transitions in shielding topological response.

Main Results:

• The metamaterial reversibly switches between topologically distinct states via sparse mechanical inputs.
• Topologically protected edge stiffness is robust against defects like broken hinges.
• Shape memory polymer phase transitions prevent topological response from stress caching.

Conclusions:

• This work provides a blueprint for defect-robust, transformable topological mechanical metamaterials.
• The developed metamaterial circumvents vulnerability to stored elastic energy.
• Potential applications include switchable acoustic diodes and tunable vibration isolators.