Magnetic-Driven Viscous Mechanisms in Ultra-Soft Magnetorheological Elastomers Offer History-Dependent Actuation with...

Area of Science:

• Materials Science
• Soft Matter Physics
• Mechanics of Materials

Background:

• Magnetorheological elastomers (MREs) are smart materials whose properties change in response to magnetic fields.
• Understanding the interplay between magnetic actuation and viscoelastic behavior in soft MREs is crucial for advanced applications.

Purpose of the Study:

• To elucidate how microstructural rearrangements in soft MREs affect viscoelastic behavior during magnetic actuation.
• To explore the potential for inducing and controlling force-memory effects in MREs through magnetic stimuli.

Main Methods:

• Experimental investigation of mechanically confined and very soft MREs under magnetic actuation.
• Analysis of viscoelastic response, including relaxation times, under varying magnetic field amplitude and actuation rate.
• Development of a theoretical magneto-mechanical continuum model to understand underlying mechanisms.

Main Results:

• Magnetic actuation significantly increases MRE relaxation times (order of magnitude) compared to purely mechanical effects.
• Viscous response modulation is tunable by magnetic stimuli characteristics and linked to particle microstructural rearrangements.
• Magnetic-driven yielding and force-memory effects were induced and subsequently erased by magnetic field removal.

Conclusions:

• Microstructural rearrangements are key to modulating viscoelasticity in soft MREs under magnetic fields.
• Magnetic actuation offers a novel pathway to engineer materials with tunable force-memory capabilities.
• The findings pave the way for new soft sensor-actuator and reservoir computing systems.