Define the control parameters to improve the solution.
The default solution controls in ANSYS typically do not allow for a robust and efficient solution in a progressive failure simulation of a composite structure. Specific solution control parameters allow for a solution with a decreased tendency for time increment cutbacks when used with Helius PFA. This results in a faster overall solution time. These solution controls are defined in the following steps. For further information regarding each command, refer to the ANSYS documentation and the Helius PFA User's Guide.
Within Tutorial_2_ANSYS.ans, locate the command:
D,P51X, ,0.06, , , ,UY, , , , ,.Directly below this command, insert the following:
NROPT,FULL,,OFF
PRED,OFF,,OFF
NSUBST,50,50,50
NEQIT,1000
TIME,1
FINISH
/SOL
CNVTOL,F,,,0The NROPT command instructs ANSYS to use the 'Full' Newton Raphson algorithm and prevents it from using the 'Adaptive Descent' algorithm.
The PRED command prevents ANSYS from using the converged solution at the last substep to estimate the solution for the current substep.
The NSUBST command specifies the number of substeps to be used in the analysis. For this tutorial, 50 substeps will be imposed. Multiple substeps help to identify when failure initiates and how it progresses as the load increases.
The NEQIT command specifies the number of equilibrium iterations that must be performed before ANSYS evaluates the need to reduce the time increment size. It is intentionally large in order to force ANSYS to converge at each of the specified time steps.
The TIME command simply specifies a step size equal to 1.
The CNVTOL command defines the convergence tolerance for residual node forces.