Problem with fortran code for solving large strain 2D elastic problem by FEM using Updated Lagrangian Framework
I am using my own fortran code to solve a large strain 2D elastic problem using FEM in Updated Lagrangian framework and I am using incremental formulation. It works well for 2D pull of a square block with 2 elements and I've compared the results with a commercial FEA package. But while solving bending of a cantilever beam the results starts to blow up and the elements distort abruptly after certain time step. This happens only when the load or the displacement given at the free end of the beam is large otherwise it works fine.