Drop-on-coilable-fibre systems exhibit negative stiffness events and transitions in coiling morphology

Area of Science:

• Mechanics of Materials
• Soft Matter Physics
• Fluid-Structure Interaction

Background:

• Elastic fibers carrying liquid droplets present complex mechanical behaviors.
• Buckling can localize within the droplet cavity in thin fibers, creating a drop-on-coilable-fiber system.

Purpose of the Study:

• To analyze the unconventional mechanical response of drop-on-coilable-fiber systems.
• To investigate the underlying mechanisms of negative stiffness events in these systems.

Main Methods:

• Theoretical analysis
• Numerical simulations
• Experimental validation

Main Results:

• Evidence of negative stiffness events was found, characterized by a liquid-like response under compression and solid-like response under tension.
• The primary negative stiffness regime results from the transfer of capillary energy to mechanical curvature energy.
• Subsequent negative stiffness events are linked to alterations in the fiber's coiling morphology, leading to a locked, ordered phase.

Conclusions:

• The drop-on-coilable-fiber system exhibits unique mechanical properties, including negative stiffness.
• Energy transfer and morphological changes in the fiber dictate its unconventional deformation behavior.
• These systems demonstrate a coexistence of liquid and solid deformation characteristics.