NLMON

Bulk Data Entry Defines the settings for runtime monitoring of nonlinear analysis.

Format

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NLMON ID PARAM1 VALUE1 PARAM2 VALUE2 PARAM3 VALUE3
PARAM4 VALUE4 PARAM5 VALUE5 PARAM6 VALUE6

Example

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NLMON 23 DISP ITER GRID 4 DOF 1

Definitions

Field Contents SI Unit Example
MID Nonlinear Monitoring Entry ID.

No default (Integer > 0)
DISP Controls the output of displacement results in the _nl.h3d file. The _nl.h3d file is output on-the-fly to help with monitoring of Nonlinear Analysis runs. 1
The value of this parameter determines the output intervals.
INC
Outputs displacement results for every increment.
ITER
Outputs displacement results for every iteration.

No default (String)
GRID Grid point identification number for which the displacement results are being monitored in the .monitor and _ld.monitor files.

No default (Integer > 0)

DOF Degree of freedom of the Grid point specified via the GRID parameter on this entry. The displacement value is output in the Global Coordinate system. The Global Coordinate system in OptiStruct is a collection of all local coordinate systems in the model (CD on GRID entry).

No default (Integer > 0)
OVERWRITE Controls how the results are written to the _nl.h3d file.
YES
The results from the previous increment are overwritten with results from the current/latest increment. Also, when YES is specified, each subcase has its own separate _nl_sub#.h3d file which contains the results data, and a single _nl_model.h3d file which contains the model data.
NO (Default)
The previous increment results are not overwritten.

Comments

  1. NLMON entry controls the following results.
    1. Nonlinear runtime results monitoring via the _nl.h3d file, and additionally convergence table information for the specified intervals which is output to the _nl.out file (and visualized via the os_out_file_parser.tcl script in HyperView). For more information, refer to Runtime Monitoring.
    2. The _nl.h3d file, in addition, this also contains Grid Sets identifying contact status changes and element sets which identify distorted elements. The _nl.out file contains a summary of the contact change grids and distorted elements, and the corresponding printing can be controlled via the NLPRINT Bulk/Subcase pair.
    3. NLMON also allows you to identify a particular GRID and DOF for corresponding incremental output in .monitor and _ld.monitor files. If the GRID and DOF parameters are not specified, the corresponding maximum translational displacement among all grids (only magnitude), and the corresponding DOF is output to those files.
  2. The <filename>.monitor and <filename>_ld.monitor files are output by default for any nonlinear analysis; however, the displacement results for a particular DOF are output only if the NLMON Bulk Data and Subcase Information Entries are specified, and the values of GRID and DOF have to be provided.
  3. The <filename>_ld.monitor contains the load displacement data of all nonlinear subcases. The file can be read in HyperMesh directly, to visualize the curve.
  4. NLMON is currently supported Nonlinear static and Nonlinear Transient analysis only. By extension to Nonlinear Transient Analysis, it is also supported for Structural Fluid-Structure Interaction (FSI). NLMON is supported for Nonlinear Optimization runs.