Bulk Data Entry Defines incremental result output parameters for Nonlinear Implicit Analysis (static and transient) and Nonlinear Explicit Analysis.


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Field Contents SI Unit Example
ID Each NLOUT Bulk Data Entry should have a unique ID.

No default (Integer > 0)

NINT Number of intervals specified to output intermediate results. 2 8

Default = 10 (Integer > 0)

SVNONCNV Output the non-convergent solution flag, if nonlinear iterations does not converge.
YES (Default)
FREQ Frequency at which the intermediate results are output.

Default = See Comment 4 (Integer > 0)

TIME Identification number of a SET entry which defines the set of time points at which the incremental nonlinear output is requested. 5 6

Default = See Comments 4 and 5 (Integer > 0)



  1. The NLOUT Bulk Data Entry can be selected by the Subcase Information Entry NLOUT=ID, or by specific result I/O Entries (3) for Nonlinear Implicit Analysis.
  2. If the difference in load increment from previous load level to the current load level that has been already output to the current load increment is greater than 1/NINT, then the intermediate result corresponding to current load level is saved for output; otherwise, it is not saved. This parameter has no control on the adaptive load size selection. Additionally, it is important to note that the difference from the current load increment to the previous output load increment is calculated based on the previous “output” load increment. Which implies that for the purposes of calculating the difference, the previously output increment is considered, and not just the previous analysis increment.

    The following example illustrates the handling of intermediate output when NINT=10 is specified.

    Since NINT=10, the value of 1/NINT is 0.1. Therefore, if the difference in load increment from the previous load level that has already been output to the current load increment is greater than 0.1, then the current load increment is selected for output. For NLOUT, the first and last increments are always output by default. In the following case, the first load step is 0.0 and the final load step is 1.0.

    Figure 1.

    Since the last output frame was 0.0 (last load increment selected for output), the difference between the next load increment and 0.0 should be greater than 0.1 (1/NINT) for it to be selected for output. As indicated in the .monitor file, printing in Figure 1, the first load increment for H3D NLOUT output after 0.0 is 0.142, since 0.0 subtracted from 0.142 is 0.142; which is greater than 0.1. For all other load increments prior to 0.142, the difference is less than 0.1, leading to them not being selected for output.

    This is clearly evident in Figure 2 from the corresponding H3D file, as the second increment to be output is 0.142, instead of 0.02 as seen in the .monitor file output in Figure 1.

    Figure 2.
  3. The following results are currently supported for incremental output:
    • Main H3D file (incremental output in main *.h3d file and OPTI format file).

      If only NLOUT Bulk/Subcase Entries are specified, then incremental output in H3D/OPTI format is output to DISPLACEMENT, STRESS, STRAIN, ELFORCE, CONTF, GPFORCE, SPCFORCE, MPCFORCE (only LGDISP), OLOAD, CSTRESS, CSTRAIN, CFAILURE, and THICKNESS.

    • The _impl.h3d file is output on-the-fly dynamically during runtime and is in addition to the main H3D file (the main H3D file is only output at the end of the run). The two options are:
      • The NLOUT Bulk Data Entry should be selected by argument NLOUT=ID of the I/O Information Entries, STRAIN, STRESS, SPCFORCE and CONTF for output of on-the-fly results in *_impl.h3d, or,
      • The PARAM,IMPLOUT,YES entry should be specified in conjunction with NLOUT Subcase/Bulk Data Entries.
    • The .pret file (incremental on-the-fly output in .pret file).

      The .pret file is output on-the-fly dynamically during runtime if PRETBOLT(OPTI=YES) is specified in conjunction with NLOUT Subcase and Bulk Data Entries. This is currently supported only for OPTI format output.

    • .h5 file (incremental on-the-fly output in a Hierarchical Data format file).
      • If the NLOUT Bulk/Subcase Entries are specified and HDF5 output is requested, then incremental output is available for DISPLACEMENT, STRESS and STRAIN.
      • STRESS and STRAIN results are currently available only for CROD, CELAS1, CBAR, CBEAM, CTRIA3, CTRIA6, CQUAD4, CQUAD8, CHEXA, CPENTA, CTETRA elements.
  4. If FREQ is set to “n”, then every n’th load level is saved for output, with counting commencing from the second load increment.
  5. NINT, FREQ, and TIME options are mutually exclusive. If one or more of NINT, FREQ, and TIME are specified, then TIME has the highest priority, followed by FREQ, and then NINT. If none of them are specified, then NINT, which has a default of 10, is used for intermediate results output.
  6. For the TIME option, a SET Bulk Data Entry of TYPE=TIME should be referenced. This allows the specification of a set of time points at which the incremental nonlinear output is requested. An example usage of NLOUT with TIME option:

    The above input will generate incremental nonlinear output at all the specific time points listed on the SET #57 Bulk Data Entry.

  7. If NLOUT is specified, then for a particular nonlinear subcase, the first and last load increments are always output regardless of the option used (NINT, FREQ, TIME). Additionally, for the FREQ option, the second load increment is also always output in addition to the first and last load increments. Counting for the FREQ option commences from the second load increment.
  8. Current support of the fields are:
    • Nonlinear Implicit analysis (static and transient): All fields are supported
    • Nonlinear Explicit analysis: Only NINT is supported