Innovation Intelligence ® RBE3 Reduction Macro Dennis D. Schwerzler March 27, 2012

Copyright © 2012 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved. RBE3 ISSUE A problem that exists today in many models is that they have very large RBE3’s. It is very easy in HyperMesh to create these large RBE3’s by just grabbing a large area using the windows option to define the independent grids. Very large RBE3’s (greater than 500 legs) can drastically increase the run times of different types of analyses on the model. This is especially true when the UM continuation data is used. These very large RBE3’s in almost all cases can be reduced down to 100 to 200 legs without any change in the results. Two things can be done to improve the run times. Reduce the size of the RBE3 If the RBE3 is loaded at the center and the EIGRA (AMSES) eigensolver is used, use the UM data on the RBE3 to make the main grid independent by switching the dependency to other grids. However, this will increase the run time if there are many legs on the RBE3

Copyright © 2012 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved. RBE3 Reduction Macro A macro to reduce the size of the RBE3 has been created to accomplish the reduction of RBE3 legs. This macro looks at the distribution of the legs and picks a few grids from each area to give an overall distribution with a lot fewer grids. To use this macro, open up the model in HyperMesh and bring up on the screen only the RBE3’s by using the Find, Config, All buttons.

Copyright © 2012 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved. RBE3 Reduction Macro Select File, Run, Tcl/Tk script. Load up the macro attached to the last slide

Copyright © 2012 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved. RBE3 Reduction Macro You will see the window shown below created by this macro.

Copyright © 2012 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved. RBE3 Reduction Macro There are two methods. You can reduce all the RBE3’s at once, or select by hand specific ones. So, you can just select the large ones by using the second method. I recommend this second method. The “Sort system” is generally not used. First pick the “Limit for legs”. 500 is usually a good choice. Then select Tags for big RBE’s. This will show you the selected tags. You can also look into the display tag window to see the size of the selected RBE’3. Exit out of this window. Pick the “Reduction ratio” value you want. This will reduce the number of legs by that percentage.

Copyright © 2012 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved. RBE3 Reduction Macro Hit “Select by tags”. This will allow you to select the tags by display. Hit proceed. You should see the selected RBE3’s listed in the GUI. If you see number of RBE3’s selected, you did something wrong and all the RBE3’s are set to be reduced. You will then have to start over. Hit “Reduce selected”. This will reduce the selected very large RBE3’s. It should run very fast. Note that the old large RBE3’s are moved to a new component name called “^obsoluteRBEs”. Do not delete this component until you first delete the selected tags, otherwise you will get a segmentation error. “cleanup Tags” on the GUI will delete the tags. It is recommended that you save this new model under a different name in case you want to compare results or try different values of reduction.

Copyright © 2012 Altair Engineering, Inc. Proprietary and Confidential. All rights reserved. RBE3 Reduction Macro The reduction technique was applied to several models and the results were found to be the same. Below is the RBE3 reduction macro. This macro was created by Thomas Kowalewski