SOLVTYP

Subcase Information Entry

SOLVTYP - Solver Selection

Description

The SOLVTYP command can be used in the Subcase Information section to select the solver for linear and nonlinear static subcases, dynamic subcases, nonlinear geometric implicit static subcase (ANALYSIS=NLGEOM), and nonlinear geometric implicit dynamic subcase (ANALYSIS=IMPDYN).

Format

SOLVTYP = option

Argument

Options

Description

option

< SID >

SID:

Set identification of an SOLVTYP bulk data entry.

Selects a SOLVTYP bulk data entry that is used to define various settings for the solver, such as different pre-conditioners and convergence criteria for the solver.

Comments

1.	Only one SOLVTYP entry can be defined for each linear and nonlinear static subcases, dynamic subcases, or nonlinear geometric implicit subcases.

2.	If present above the first subcase, it is applied to all compatible subcases. For more details on subcase type and solver compatibility, refer to the SOLVTYP bulk data entry.

If SOLVTYP is present in a subcase, a solver, specified by the referenced SOLVTYP in the bulk data, is used in the solution of the compatible sections of, or of the corresponding total subcase. The option selects the SOLVTYP bulk data entry that can be used to define alternate settings such as different pre-conditioners and convergence criteria for the solver.

4.	In optimization, if the responses DRESP1, RTYPE = DISP, LAMA, STESS, STRAIN, CSTRESS, CSTRAIN, CFAILURE, or FORCE are present the solver is automatically reverted to the direct solver.

5.	The iterative solver is a preconditioned conjugate gradient solver. A Factored Approximate Inverse Preconditioner is the default method. This solver is also SMP parallelized.

The performance of the iterative solver depends on the conditioning of the stiffness matrix. For compact solid models, the iterative solver may perform considerably better than the direct solver in terms of memory usage and elapsed times for a single linear static subcase. In the case of multiple linear static subcases, the iterative solver may perform worse than the direct solver. The break-even point is at about 4-6 subcases. The performance depends on model, hardware, operating system, and potentially the system load.