,understood. Thank you for answering. I was thinking that since stiffness matrix itself depends on the response of the nodal displacements, so I cannot conduct a LU decomposition on it. But apparently the LU decomposition can also work on a non-linear set of equations where the stiffness matrix itself is a funtion of the nodal displacements. But still I am slightly confused that if the convergence is not achieved for a specific iteration for a specific time step, then still there are no guesses made (since LU decomposition, by theory and its name, doesn't involve any guesses)? If not, then how does the iterations proceed?
And also, as you have mentioned that the Iterative solver requires only one iteration to converge at t = 1 sec i.e. the final time step for a linear analysis. So is it possible that the solution doesn't converge at that time step ? What measures can be taken to make the linear analysis converge at the one and only i.e. final time step?