Quasi-2D dynamic jamming in cornstarch suspensions: visualization and force measurements

Area of Science:

• Rheology
• Soft Matter Physics
• Material Science

Background:

• Cornstarch suspensions exhibit jamming behavior, transitioning from liquid to solid states under impact.
• Understanding jamming fronts is crucial for predicting material behavior in dynamic scenarios.

Purpose of the Study:

• To investigate the dynamics of jamming fronts in a floating cornstarch suspension.
• To analyze the propagation characteristics and force response during the jamming process.

Main Methods:

• Experiments were conducted on a floating layer of cornstarch suspension near its jamming point.
• High-speed impact was used to initiate jamming.
• Propagation in axial and transverse directions was measured.
• Force response was monitored during the growth of the jammed solid.

Main Results:

• The jamming front propagated with a constant axial-to-transverse ratio of approximately 2.
• An additional compression was observed within the jammed solid due to increasing stress.
• Initial force response was consistent with added mass.
• A delay in force response was observed after the jamming front reached a boundary, preceding a uniform velocity gradient development.

Conclusions:

• Jamming front propagation in cornstarch suspensions is anisotropic.
• The force response dynamics are complex, involving added mass effects and a delayed response related to system-wide velocity gradient development.