ANSYS Iterative Solver , Direct Sparse Solver & Newton Raphson Algorithm Question ?

[Anil_O]

Hello everyone,

I have a question about the FEM solution procedure.

Suppose I have model with nonlinear effects. Basically, K is also a function of u. I use 10 substeps with automatic time stepping. Condition 1:

1) I choose Direct sparse solver as an equation solver and for equilibrium equation solver NR.

Basically , Where does the program use the Sparse Solving technique, and where the Newton Raphson ?

Condition 2:

2) I choose PCG solver (or any iterative solver) for equation solver and again NR for the equilibrium equations.

How does the program implement NR and and PCG algorithm ?

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As far as I know, NR give us the final Ki (Tangent matrix) at each substep and equation solver comes into the scene to solve the K.U=F basic equation depending on the algorithm (Direct or Iterative).

If anyone with the good academic background help me about the questions or give his / her comments, I would be appreciated.

Thanks