Dense suspensions as trainable rheological metafluids

Area of Science:

• Materials Science
• Rheology
• Soft Matter Physics

Background:

• Adaptive material performance can be enhanced by memory effects.
• Dense suspensions typically exhibit limited memory, hindering sustained adaptive behavior.
• Non-Newtonian rheology in suspensions enables stress-adaptive responses.

Purpose of the Study:

• To design dense suspensions with multiple, distinct stress-activated memories.
• To enable suspensions to adaptively stiffen or soften based on stress levels.
• To explore the concept of trainable rheological metafluids.

Main Methods:

• Designing suspensions with dual particle interactions: frictional contact and dynamic chemical bridging.
• Investigating the interplay between these interactions to create stress-dependent memory effects.
• Characterizing the rheological response, including viscosity and energy dissipation, under varying stress conditions.

Main Results:

• Demonstrated that different stress levels can trigger distinct memory responses in dense suspensions.
• Showcased suspensions that can be trained to either soften or stiffen adaptively.
• Observed targeted viscosity and energy dissipation in response to low-velocity impacts.

Conclusions:

• Dense suspensions can be engineered to possess multiple, stress-activated memories.
• This multi-memory characteristic allows for trainable rheological behavior, akin to mechanical metamaterials.
• The developed suspensions can be considered trainable rheological metafluids, opening new avenues for adaptive materials.