OSSmooth Parameter File

Parameter statements in the OSSmooth parameter file.

OSSmooth file parameter statements each have following format:
parameter_name        arg1,arg2,...,argn

The parameter_name and arguments can be separated either by spaces or commas. The file is not case sensitive.

Comment lines in the OSSmooth parameter file should start with either ‘#’ or ‘\$’.

Supported Parameters

input_file
Identifies the files to be interpreted by OSSmooth.
arg1
The file name (without extension) of the OptiStruct .fem, .sh, and/or .grid files to be interpreted by OSSmooth.
output_file
Name of the file to be output by OSSmooth.
arg1
Full name of the file output by OSSmooth.
output_code
Identifies the type of output.
arg1
Output format for iso-surface
• "1" Bulk data trias
• "2" IGES patches
• "3" STL trias [default]
• "4" H3D trias
arg2
Output control for tet-meshing of volume enclosed by the iso-surface.
[Default: no tet-meshing]
• "1" Tetra4 + Tria3 elements
• "2" Tetra10 + Tria6 elements
• "3" Tetra4 elements
• "4" Tetra10 elements
The tet-mesh is written in OptiStruct input format to a file <input_file>_mesh.fem. In this file, the design space of the file <input_file>.fem is replaced with a tet-mesh for immediate reanalysis. Loads, boundary conditions, and non-design elements are carried over from the input file.
units
Defines output units for IGES format. This information gets written to the header of the IGES file and may be recognized by your CAD system.
1 (default)
inch
2
mm
4
foot
10
cm
Improves the recovered geometry from a topography optimization by applying automatic geometry creation.
arg1
Operation flag [integer]
arg2
[real, between 0.0 and 1.0, default = 0.3]
arg3
• "1 (default)" create 1 layer bead
• "2" create 2 layers bead
isosurface
Generate threshold surface from a topology optimization by applying automatic geometry creation.
arg1
Operation flag [integer]
• "0" isosurface off
• "1 (default)" isosurface on
arg2
Type of surface created [integer]
• "0" isosurface only
• "1" isosurface with Optimization-based smoothing
• "2" Element threshold surface
• "3 (default)" isosurface with Laplacian smoothing
For topology results, smoothing maintains the topology as suggested by OptiStruct, but it can deviate from the given density distribution. If option 1 or 3 is used, check the maximum and average smoothing error output by OSSmooth.
arg3
Density threshold for creating isosurface.
[real, between 0.0 and 1.0, default = 0.3]
opti_smoothing
Optimization-based smoothing [Only used if isosurface C2=1].
arg1
Unit-less surface distance coefficient
[real, default = 0.0]
Defines closeness of the smooth surface from the threshold surface. The effect of this coefficient varies for different input meshes. Higher magnitudes, both positive and negative, give smoother results, but the surface deviates more from the original density distribution. The recommended range is from -50 to 50. When the coefficient is set between 0 and 50, the surface usually tends to smooth and shrink. When the coefficient is set between 0 and -50, the surface usually tends to smooth and expand.
arg2
Smooth isosurface boundary flag [integer]
• "0 (default)" boundary not included in smoothing
• "1" boundary included in smoothing
laplacian_smoothing
Laplacian smoothing [Only used if isosurface C2=3].
arg1
Number of iteration for Laplacian smoothing
[integer > 0, default = 10]
arg2
Feature angle threshold in degrees
[real, default = 30.0]
The feature angle is defined as the angle of normal between two intersected element planes. All corners with a feature angle larger than the threshold will be preserved in the smoothing process.
arg3
Smooth isosurface boundary flag [integer]
• "0" boundary not included in smoothing
• "1 (default)" boundary included in smoothing
remesh
Remesh autobead surface and/or isosurface flag [integer]
0 (default)
remesh off
1
remesh on
Remesh detects 2-layer elements around bead shape and/or boundary of isosurface. Use mixed type remesh if input mesh contains any QUAD elements, otherwise remesh with TRIA elements.
surface_reduction
Reduces the number of surfaces representing the geometry. Can reduce the number of surfaces by up to 80 percent.
arg1
Surface reduction flag [integer]
• "0 (default)" no surface reduction
• "1" do surface reduction
arg2
Feature angle threshold in degrees
[real, default = 10.0]
The feature angle is defined as the angle formed by the surface normal of two adjacent elements. The surface reduction will be performed on any two adjacent elements in which the feature angle between the two elements is smaller than the threshold. The greater the threshold, the more surface reduction will be conducted. The valid range of the threshold is [1.0, 80.0].
pure_surf_smoothing
Surface smoothing only.
arg1
Pure surface smoothing flag [integer]
• "0 (default)"
• "1" Optimization-based smoothing
• "2" Laplacian smoothing
arg2
Number of iteration [Only used if G1=2]
[integer > 0, default = 10]
arg3
Feature angle threshold in degrees [Only used if G1=2]
[real, default = 30.0]
The feature angle is defined as the angle of normal between two intersected element planes. All corners with a feature angle larger than the threshold will be preserved in the smoothing process.
pure_surf_reduction
Surface reduction only.
arg1
Pure surface reduction flag [integer]
• "0 (default)" no surface reduction
• "1" do surface reduction
arg2
Feature angle threshold in degrees
[real, default = 10.0]
The feature angle is defined as the angle formed by the surface normal of two adjacent elements. The surface reduction will be performed on any two adjacent elements in which the feature angle between the two elements is smaller than the threshold. The greater the threshold, the more surface reduction will be conducted. The valid range of the threshold is [1.0, 80.0].

OSS Example Input File

input_file example
Identifies the root of the input files as example, so OSSmooth will look for the files example.fem, example.grid, and example.sh.
output_file example.stl
The resulting output will be example.stl.
output_code 3
The output will be in stereolithography format.