Hello,
I am doing reduced order modelling for nonlinear analysis and I have to use the POD and Galerkin projection to reduce my matrices size. The problem is that since it's a nonlinear analysis, the matrices have to be updated for each increment. And for commercial FEA softwares, I do not have access to the stiffness matrices for each step time.
Does someone have any suggestions (using abaqus subroutines for example).
Thank you in advance.
You can access the nonlinear internal force using (NFORCE) instead of updating the stiffness matrix.
Lam Nguyen , thank you for your response. But how about the tangent stiffness matrix (in Newton-Raphson method) ?
To reduce my model, I also need to project this matrix in the POD reduced basis. Another point is how I give the reduced matrices to abaqus to solve the reduced equation.
Thank you !