Hi!
I created a 2D axisymmetrical model to examine the deformation of a (stem) cell on a (polyacrylamide) gel after contraction.
In order to do so, I should define a prestress over a part of the cell (the cytoplasm). However, since the cytoplasm is made up of a hyperelastic Neo-Hookean material, it is not possible to define a prestress -I used "Initial stress"- in a way it is possible for a linear elastic material (also, when applying linear elastic materials, the model does only converge for a positive prestress, so radially outward, instead of radially inward as in a contraction).
What could cause the model to not converge for a radially inward prestress?
And is there any other way to define a prestress for a Hyperelastic Material, to imitate contraction?
Thank you in advance!