Solving Linear and Nonlinear Models? Direct / Iterative methods?

Joel Rodarte

I did some research and saw on Altair Documentation that both Linear and Nonlinear models are solved by Direct Methods,

                Boeing Solver for linear static and MUMPS solver for nonlinear static,

 

My understanding, and what I see on my .out file, is that nonlinear models are solved iteratively instead of direct as documentation suggests; So, my next questions are:

 

1) NonLinear quasiStatic  is solved in an iterative or direct method?

2) What does the documentation mean that  the default solver for non linear static uses a direct solver?

 

Thank you!

 

  

       

 

FaroukM

1) NonLinear quasiStatic  is solved in an iterative or direct method?

 

In general, you can do what you want : you can use an iterative or direct solver. Direct solvers are recommended if your models are highly nonlinear (frictional contact for example). But they are time consuming especially if your models contain more than 1 millions dof (approximately).

 

2) What does the documentation mean that  the default solver for non linear static uses a direct solver?

If you perform a non linear static analysis, Optistruct use a direct solver (MUMPS).  You don't need to configure it.