19 May
2017
19 May
'17
6:27 p.m.
Dear all,
I have some questions about the internal behaviour of Sfepy that I hope you can answer me.
 What is it the convergence criterion of the nonlinear Newton solver?
 When modelling a Nearly incompressible MooneyRivlin hyperelastic material, like the example shown here: http://sfepy.org/docdevel/examples/large_deformation/hyperelastic.html, how the nearlyincompressibility constraint is stabilised?
Thank you very much in advance.
20 May
20 May
10:48 p.m.
Hi Patricia,
On 05/19/2017 06:27 PM, Patricia Garcia Cañadilla wrote:
Dear all,
I have some questions about the internal behaviour of Sfepy that I hope you can answer me.
 What is it the convergence criterion of the nonlinear Newton solver?
For example, this means:
'i_max' : 5,
'eps_a' : 1e10,
'eps_r' : 1.0,
'eps_mode' : 'and',
max. 5 iterations, the solution is considered converged if the absolute residual l2 norm r_i is smaller than eps_a and/or the relative residual norm (r_i/r_0) smaller than eps_r. The and/or behaviour is determined by eps_mode, 'and' is the default.
 When modelling a Nearly incompressible MooneyRivlin hyperelastic material, like the example shown here: http://sfepy.org/docdevel/examples/large_deformation/hyperelastic.html, how the nearlyincompressibility constraint is stabilised?
It is not stabilized in that example  the bulk modulus is high enough to have a small compressibility and low enough in order not to cause convergence problems.
r.
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Patricia Garcia Cañadilla

Robert Cimrman