General Tips
A more detailed description of all items is given inside the following example
1. Don’t merge nodes before all the meshing is done. In case you sticked nodes and you want to destroy geometry, you have to unlink all nodes from the geometry you want to destroy before.
2. There is no undo. Save your work before you do more extensive actions. Alternatively, you can stop the software, edit the file SYSTUS.ESP, delete the lines with the commands you don’t want, save the file under the name RUN.ESP (just an example), start the software again and run the file RUN.ESP.
3. If a volume can’t be meshed, list it and find the basic domain of the volume which is used to create the volume. Then try to mesh this domain. If it works, the volume can be meshed then, with an existing mesh on the basic domain. If the basic domain can’t be meshed, you have to modify it until it can be meshed.
4. If the names of the entities you want to display are not displayed, even if the names button is activated, erase these entities from screen, type defi /nam acti and display them again
5. If you save a database *.MOS, it can take some time due to the saving of the file *.hmf. If you want to avoid that, save the database as *.MOC and rename it to *.MOS with your explorer. Since version 2000, the storage of the file *.hmf can be switched of.
6. Before you write the input file for the solver, try to delete all nodes. Free nodes without elements are then deleted, connected nodes not
7. There is a difference between a surface and a domain. The domain can be meshed, the surface not. In general FEM technology, the domain is the to be meshed area which you trim on a surface, which can be bigger then the domain to be meshed. In case of simple domains (translation, rotation etc.) the area of the domain is the same as the area of the surface where the domain is trimmed on. In the general case, the surface has not the same area as the domain
8. In a CAD-system, edges must be not closed, that means the end point of one lineic entity must be not the same as the start point of the following linieic entity. In SYSWELD, this is not the case, the points have to be sticked, else the edges are not closed and thus can’t be created
9. Please don’t use closed circles. This creates sometimes problems with the mesh generator. Closed circles exist to grant a compatibility to IGES files; Once you loaded them, you should switch them into two semi-circles.
10. If you have a low amount of workspace (RAM) and you do large actions like symmetry copies, you should store the database afterwards, quit the software, restart it and reload the stored file. In case that you have a large amount of workspace, this is not necessary
11. In case you load an IGES file you should start it and check the numerical precision of this file. Then you interrupt this loading and set the system internal sticking distance to 10 times of the sticking distance that has been given as numerical precision of the IGES file (>defi /sep value). Then you can load the IGES file and accept the numerical precision given
12. Please don’t use polylines. If you have to use them , don’t stick nodes before you finished the modeling. There is sometimes a database problem with these entities. This problem will be fixed.
13. If you have loaded an IGES file, you should erase the screen an display all splines and all points that constitute the splines. A good spline is a spline where the trimming points have more or less equidistant distance. A bad spline is a spline where there is a point at the beginning and at the end, and 100 trimming points in the middle with a very low distance of the points. All the preprocessor is done in single precision (all the solver is in double precision), and such splines create numerical problems in the mesh generator. To avoid such problems, you can create splines with equidistant distance on existing splines, and then destroy the original ones. If you want to avoid further problems, it is mandatory to destroy the bad splines.
14. To create ruled surfaces / domains, all lineic entities should point in the same direction.
15. To create ruled volumes, all lineic entities should have the same running direction, and a spline through the starting points of the edges should be not twisted.
Example for a good working style
# Set the tolerance to merge nodes to a value which
# is about 10 times coarser then the precision given
# from the iges file. This is the magic key when
# loading iges files. Edges which have been accepted
# as closed in CAD systems which don’t need a common
# point at the end of a lineic entity and at the
# beginning of the next lineic entity are then also
# accepted as closed in Sysweld. If this is not the case
# edges are not created during loading, and as a
# consequence, also the geometric entities not which
# are based on these edges. In case of doubt you should
# try different values and just compare the number of
# entities in the database at the end (>info /nbr)
DEFI /SEP 0.01
RETR WHEEL.IGS
# load an iges file. Center the image
.10000E-02
# Create lines as basis for closed edges. Zoom on
# the needed points before
LINE P24 P31
LINE P14 P13
# Create edges from lineic entities that form a closed
# circuit. Click only the first line, the others will be
# proposed by the software
# Switch of the display of points before (click mode,..)
#
CNTR L25 CB19 L15 L16 CB17 CB18 L14 L13 CB16
CNTR L17 CB21 L19 CB29 L18 CB10
CNTR L26 CB3 L5 L6 L7 L8 CB4
#
# Display all the structure (center). Switch off the
# display of the names of lines and B-splines
#
# Delete then all the garbage that is not needed any
# more out of the database. Make use of the hierarchical
# structure of the database. Points, lines and B-splines
# which constitute the edges can’t be deleted until the
# edges are deleted. So if you enter dele /lin, only the
# lines are deleted which are at the end of an
# hierarchical list
dele /cbsp
Y
#
dele /lin
Y
#
dele /poi
Y
# Now you save the data. Not in the usual manner but
# as file *.MOC. Seen from it’s content, it is exactly
# the same as a *.MOS file. However, when you load it,
# it’s content is added to the existing structure, by
# re-arranging the data structure.
# For cleaning an IGES file, we are using this feature
# If we load later on the file CLEAN_IGS.MOC we are
# saving now in an empty database, we have what we
# need to go on in an optimized data structure, and
# all the garbage is gone.
# If you are a person which wants to work always
# with a perfectly organized database, it is a good
# working style to save always a database as *.MOC
# and reload it in an empty workspace. If you want
# to increase the loading speed in case of big
# databases later on, you just rename it in *.MOS
# on the level of the operating system.
#
SAVE CLEAN_IGS.MOC
# Now you delete the workspace of the pre-processor
# Please keep in mind that there is a difference
# between the button ‘erase’ and ‘destroy’. ‘destroy’
# really destroys data stored in the workspace,
# while ‘erase’ clears only the screen or selected
# entities.
# The database has been deleted before, so it is
# not lost. However, the workspace is empty!
DELE /ALL
Y
# If a *.MOC file is loaded, it’s data is added to
# the existing data in the workspace. The position
# of the origin of the system of coordinates has to
# be given, and a transformation matrix. Thus,
# new parts can be loaded to the existing database
# in any position in space. If you want to load it at
# the initial position, you just hit return for the
# defaults
#
RETR CLEAN_IGS.MOC
0.00000E+00
0.00000E+00
0.00000E+00
0.10000E+01
0.00000E+00
0.00000E+00
0.00000E+00
0.10000E+01
0.00000E+00
0.00000E+00
0.00000E+00
0.10000E+01
# Now a database CLEAN_IGS.MOS is saved, having
# clean and optimized data structure
# save CLEAN_IGS
more
# The final goal is to get a good solid mesh for
# quenching. Thus, domains are created from edges,
# and volumes are created from the domains.
# One existing edge is not good regarding the final
# mesh, so you have to modify it. This is done right
# now
#
# Show the entities you need to do the work
SHOW F1
SHOW /1DS /CON F1
SHOW /POI /CON L5 L6
SHOW /POI /CON CB6 CB5
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