Modify the Solution Control Parameters

Adjust the control parameters for the solver to work best with Helius PFA.

Solution Sequence

When Autodesk Nastran is used with Helius PFA, you must run a nonlinear static analysis.

Navigate to the top of the input file and add the following:
```
SOL NLSTATIC
```

Nonlinear Solution Controls

Many linear elastic analyses require only a single increment per step. However, a single increment is inadequate when modelling progressive failure because multiple increments are required to visualize the initiation and propagation of failure.

Locate the PARAM,HEXREDORD,OFF entry.

On the line below, add the following:

NLPARM         1     100            ITER       1    1000             ALL+       
+                                   1000                                +       
+

The NLPARM entry defines the nonlinear solution controls and time incrementation for the analysis. As defined in this tutorial, it instructs Nastran:

to use 100 increments for the total solution time. This allows us to examine the progression of failure.
to use the full Newton-Raphson iteration method and update the stiffness matrix at every iteration.
to perform up to 1000 iterations before evaluating the need to reduce the time incrementation. This allows Nastran to take advantage of the enhanced convergence characteristics provided by Helius PFA.

With the modifications to this point, the input file should appear as follows:

SOL NLSTATIC
CEND
$ SUBCASE 1
  ECHO = NONE
  DISPLACEMENT(PLOT) = ALL
  SPCFORCE(PLOT) = ALL
  FORCE(PLOT,CORNER) = ALL
  NLSTRESS(PLOT) = ALL
  STRESS(PLOT,CORNER) = ALL
  STRAIN(PLOT,CORNER) = ALL
  SPC = 2001
  NLPARM = 1
  LOAD = 1
BEGIN BULK
$  
PARAM,UNITS,IN-LBF-BTU-SEC
PARAM,LGDISP,0
PARAM,OGEOM,NO
PARAM,AUTOSPC,ON
PARAM,GRDPNT,0 
PARAM,NLTOL,2 
PARAM,SOLUTIONERROR,OFF
PARAM,HEXINODE,OFF
PARAM,HEXREDORD,OFF  
NLPARM         1     100            ITER       1    1000             ALL+       
+                                   1000                                +       
+
$
$ MAT1, 9031, 1.806E+07      
MATPFA, 1, 9031, 1, MCT, 0.01, 0.001, INSTANT, OFF,
, , AMBIENT, , , 1
$
CORD2R, 11, , 0.0, 0.0, 0.0, 0.0, 0.0, 1.0,
, 0.0, 1.0, 0.0
$       
$LAYERED SOLID LAYUP
PCOMPS,  2, 11, , , ,
      ,1,  1,  0.006,    45.,   ,   ,YES,
      ,2,  1,  0.006,     0.,   ,   ,YES, 
      ,3,  1,  0.006,   -45.,   ,   ,YES,
      ,4,  1,  0.006,    90.,   ,   ,YES,
      ,5,  1,  0.006,    45.,   ,   ,YES,
      ,6,  1,  0.006,     0.,   ,   ,YES,
      ,7,  1,  0.006,   -45.,   ,   ,YES,
      ,8,  1,  0.006,    90.,   ,   ,YES,   
      ,9,  1,  0.006,    45.,   ,   ,YES,
      ,10,  1,  0.006,     0.,   ,   ,YES, 
      ,11,  1,  0.006,   -45.,   ,   ,YES,
      ,12,  1,  0.006,    90.,   ,   ,YES,
      ,13,  1,  0.006,    90.,   ,   ,YES,
      ,14,  1,  0.006,   -45.,   ,   ,YES,
      ,15,  1,  0.006,     0.,   ,   ,YES,
      ,16,  1,  0.006,    45.,   ,   ,YES, 
      ,17,  1,  0.006,    90.,   ,   ,YES,
      ,18,  1,  0.006,   -45.,   ,   ,YES, 
      ,19,  1,  0.006,     0.,   ,   ,YES,
      ,20,  1,  0.006,    45.,   ,   ,YES,
      ,21,  1,  0.006,    90.,   ,   ,YES,
      ,22,  1,  0.006,   -45.,   ,   ,YES,
      ,23,  1,  0.006,     0.,   ,   ,YES,
      ,24,  1,  0.006,    45.,   ,   ,YES, 
$