Pattern Transitions in a Soft Cylindrical Shell

Area of Science:

• Solid Mechanics
• Materials Science
• Soft Matter Physics

Background:

• Uniaxially compressed soft films on stiff substrates exhibit intricate instability patterns.
• Curvature effects significantly influence pattern transitions in soft materials.
• Previous studies primarily focused on flat substrates, limiting understanding of curved systems.

Purpose of the Study:

• To investigate pattern transitions and postbuckling phenomena in a soft shell sliding on a rigid cylinder.
• To reveal novel bifurcation scenarios on curved surfaces.
• To understand the role of curvature in soft shell instabilities.

Main Methods:

• Experimental investigation of soft shell behavior on a rigid cylinder.
• Computational modeling to simulate pattern transitions.
• Theoretical analysis to explain observed bifurcation phenomena.

Main Results:

• A novel postbuckling phenomenon with multiple successive bifurcations was identified: smooth-wrinkle-ridge-sagging transitions.
• The shell initially buckles into periodic axisymmetric wrinkles, transitioning to ridges and then sagging folds upon increased compression.
• Hysteresis loops and Maxwell equal-energy conditions were associated with the coexistence of different patterns.

Conclusions:

• The observed bifurcation scenario is general and independent of specific material constitutive models.
• Curvature plays a critical role in dictating the complex instability patterns of soft shells.
• This research provides fundamental insights into the mechanics of soft materials on curved surfaces.