large deformation in comsol

http://www.engin.umich.edu/class/bme456/largedef/largedef.htm

large deformation hyperelastic curve, thank you.

In this section we will only give a brief introduction to nonlinear elastic materials under large deformations, materials more generally known as hyperelastic. Many soft tissues under cyclic loading may be represented as hyperelastic materials, in a from referred to as pseudo-elastic materials. The stress-strain curve of hyperelastic materials is shown below:



Notice that the stress and strain quantities used are the 2nd Piola Kirchoff stress and the Green-Lagrange strain tensor. This serves as a reminder that to be consistent we have to derive the constitutive equations in terms of these quantities.

Next, we recall that any elastic material may be represented by a strain energy function. For Hookean (linear) elastic materials this takes the following form:

http://www.technion.ac.il/docs/comsol/sme/smeug.pdf page 94-106