[Getfem-users] non linear elasticity

[jean-yves heddebaut]

Dear getfem users,

I would like to  reuse the non linear elasticity brick to make a  
brick representing the behavior of non linear membranes.
The idea is to apply the Cosserat hypothesis, which gives a  
simplified Green-Lagrange strain tensor.

The dimension of the vgrad term in the  
asm_nonlinear_elasticity_tangent_matrix function would be (:,2,3) iso  
(:,3,3) in the 3 dim brick, and I think I could reuse the function  
without modification.
The elasticity_nonlinear_term, on the contrary, has to be adapted,  
but I do not see how to do it.
Could anybody help me understand the logic  behind the compute  
function ?

here is how I understand it, please tell me where I am wrong (I am  
considering the Saint venant kirchoff hyperelastic law)

1.gradU is the gradient of the displacements, based on the preceding  
iteration displacements

2.E is the Green-Lagrange strain tensor, also based on the preceding  
iteration displacements

3.gradU becomes gadU+I ( deformation gradient iso displacement  
gradient ?)

4.tt is a tensor containing the rigidity coefficients

Could somebody tell me what is done in the "version==0" loops ?

I would greatly appreciate any help

jean-yves heddebaut