Universal scaling of polygonal desiccation crack patterns

Area of Science:

• Materials Science
• Geophysics
• Fluid Dynamics

Background:

• Polygonal desiccation crack patterns are common but their underlying physics across scales is debated.
• Existing theories on crack formation in thin films yield contradictory predictions regarding length scales.
• The relationship between film thickness and crack characteristics remains poorly understood.

Purpose of the Study:

• To experimentally investigate the physics of polygonal desiccation cracks in drying particle suspensions.
• To determine if crack patterns across different length scales share common physical principles.
• To develop a unified framework for understanding multiscale crack formation.

Main Methods:

• Experimental investigation of drying suspensions of micron-sized particles.
• Systematic variation of film thickness, boundary adhesion, packing fraction, and solvent composition.
• Analysis of crack patterns and their characteristic areas using a universal power law.

Main Results:

• Polygonal cracks form in most systems above a critical film thickness.
• Multiscale crack patterns were observed in cornstarch-water mixtures due to distinct desiccation mechanisms (capillary shrinkage and particle deswelling).
• A universal power law, A_p=αh^{4/3}, describes the characteristic crack area (A_p) as a function of film thickness (h).

Conclusions:

• The study provides a robust framework for understanding multiscale polygonal crack patterns.
• The findings link crack formation physics to material properties, unifying observations from microscopic to geologic scales.
• The universal power law offers a predictive tool for crack behavior in various natural and engineered systems.