I am trying to implement dynamic compression to a 2D model using triphasic theory of cartilage, but I always get a singularity problem. The nonlinear solver is nonconvergent in the first time step of the time dependent solver. For the steady state case, static compression, I apply a strain_initial = -0.1, and the static case works. The initial value of the time dependent case is the solution of the steady state case. Then I add a strain = -0.025 * sin(2*pi*t*t_const*frequency).
I have tried refining the mesh (quadrilateral and triangular), lower the relative tolerance to 1e-6, and verified steps for the time dependent solver. The frequency is not too high, which is only 2.5%. Boundary conditions may not be complete, or the time-dependent dweak is wrong. Could you please help?
I have tried refining the mesh (quadrilateral and triangular), lower the relative tolerance to 1e-6, and verified steps for the time dependent solver. The frequency is not too high, which is only 2.5%. Boundary conditions may not be complete, or the time-dependent dweak is wrong. Could you please help?