In Memoriam - Prof. Dr.-Ing. Christian Miehe
Dear Sir or Madam, dear colleagues,
aquis_mech's blog
Discrepancy of numerical results from analytical solution for an nonlinear viscoelasticity model
I have written a Fortran code for nonlinear viscoelasticity according to the Hughes' recurrence algorithm based on a total Lagrangian formulation. And a relaxation test is made. There is some deviation from the analytical solution(Theoretically the stress response should be an exponential decay plus a constant, isn't it?). The numerical ultimate stress is larger than the analytical one. As a larger initial strain is applied, the deviation is smaller. For a inital strain of 10%, there is almost no difference between the num. and analy. solution. What can account for this?
Numerical phase modeling of BTO nanostructure using Landis' model with FEAP
The difference to the common model used is the f,g terms. The 3D FEM formulation has been derived and a new fortran program is written. The derivative matrix is symmetric. But the calculation result does not converge. I have tried every means to get a converging result. But it doesn't work, the residual norm always increases.