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ES 241

Elasticity of rubber-like materials

Submitted by Zhigang Suo on

In the notes on the general theory of finite deformation, we have left the free energy function unspecified. The notes here describe free energy function commonly used to describe the elasticity of rubber-like materials.  These notes are part of a course on advanced elasticity

Elastocapillarity

Submitted by Zhigang Suo on

These notes are part of a course on advanced elasticity.  The notes recall several phenomena where both elasticity and surface energy are significant, including

  • Griffith crack
  • Adhesion of flexible structures
  • Wafer bonding
  • Contraction of a soft elastic sheet 

The notes also contain a formulation of combined surface energy and elasticity of finite deformation.  

Theory of dielectric elastomers

Submitted by Zhigang Suo on

In response to a stimulus, a soft material deforms, and the deformation provides a function. We call such a material a soft active material (SAM). This review focuses on one class of soft active materials: dielectric elastomers. Subject to a voltage, a membrane of a dielectric elastomer reduces thickness and expands area, possibly straining over 100%. The phenomenon is being developed as transducers for broad applications, including soft robots, adaptive optics, Braille displays, and electric generators.

Addendum To Pressure and Chemical Potential - a question on hydrostatics

Submitted by Tony Rockwell on

The question was raised in class as to what the appropriate equilibrium condition for a column of fluid at rest should be. Specifically, given we expect a hydrostatic gradient in pressure with height, whether  the chemical potential must be the same throughout the column was questioned. Here are my first thoughts. In brief, I assert that  the chemical potential must be everywhere identical, and that the pv term is balanced, at every height in the column, by the potential energy conferred by position in a gravitational field.