Advanced
This section treats advanced options for analysis and postprocessing.
Liner solver
The option Solver type enables the user to choose the equation solver. The options are:
-
Automatic
: The program chooses the best solver depending on the size of the problem. Small problems will use option Skyline
and bigger problems will use theoption Sparse
.
-
Skyline
: A Choleskysolver with skyline storage of the matrix is used. This is a direct solver that requires a bigger amount of memory. The advantage is that it always gives a solution if the problem is correctly defined. If there are several loadcases, a direct solver can save a lot of computing time.
-
Sparse
: A conjugate-gradients solver with sparse storage is used. This is an iterative solver that requires much less memory than a direct one. It may not converge in some cases. If it does not give a solution, try the Skyline solver after checking the problem definition. If this option is enabled, several parameters can be modified:
- Solver tolerance: When two successive iterations do not differ by more than the specified tolerance, the solver will halt.
- Solver tolerance minimum: If the solver arrives at itsmaximum iteration number, this tolerance will decide if results are accepted.
- Max. iterations: maximum number of iterations permitted.
Normally, the best option is to choose Automatic
. Advanced users should choose the Skyline
solver if it does not take too much memory and Sparse
solver for big problems depending on the available RAM memory.
Eigen solver
The eigensolver used in the analysis of frequencies and modes of vibrations is the subspace iterative method. The option Eigensolver max iterations indicates the maximun number of iteration to be performed by the eigensolver.
Dynamic Output
A dynamic analysis generates a large amount of results which are passed on to the postprocessing. In order to reduce the amount of data, Rambshell offers the possibility to choose which results are required.this information Rambshell have the possibility of choose what results are required (Write Displacements, Write Velocities, Write Accelerations, Write Strengths and Write Reactions)
Using the option Output Step, the user can specify how many interim results should be included in the postprocess file.