Creasing of an everted elastomer tube

Area of Science:

• Mechanical Engineering
• Materials Science
• Solid Mechanics

Background:

• Cylindrical elastomer tubes can remain everted without external forces.
• Instability leading to noncircular cross-sections occurs above a critical thickness.
• Previous linear analyses failed to accurately predict this eversion-induced instability.

Purpose of the Study:

• To identify the mechanical instability mode in everted elastomer tubes.
• To develop accurate methods for predicting critical thickness and cross-sectional profiles.
• To address the discrepancy between existing theoretical predictions and experimental observations.

Main Methods:

• Experimental investigation of eversion-induced instability.
• Theoretical analysis incorporating finite deformation.
• Energetic analyses and numerical simulations of everted tubes.

Main Results:

• Crease formation on the inner surface is identified as the instability mode.
• Linear stability analyses were insufficient to capture this phenomenon.
• A combination of energetic analysis and finite deformation simulations accurately predicts critical thickness and noncircular cross-section profiles.

Conclusions:

• Crease formation is the key mechanical instability in everted elastomer tubes.
• Finite deformation analysis, not linear analysis, is required for accurate predictions.
• The developed methods correctly predict critical thickness and the geometry of the noncircular cross-section.