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Showing posts from March, 2018

Defining Ansys Superelement SUB File Manually

Photo by  James Owen  on  Unsplash A surprisingly popular blog-post written here is Exporting Stiffness Matrix from Ansys . A sensible follow up question is what can one do with the exported stiffness matrix? In a recent Xansys Forum post, a question was raised on how we can edit the stiffness matrix of a superelement and use it for our model.  An approach presented below is to first create a superelement that has the same number of DOF and nodal location that will serve as a template. An APDL script can then be written to edit the stiffness matrix entries as desired before exporting to a new superelement *.SUB file for use in future models. The self-contained script below demonstrates this.  /prep7 et ,1, 185 mp , ex, 1, 200e3 mp , prxy, 1, 0.33 w = 0.1 ! single element (note nodal locations) n , 1, w, -w, -w n , 2, w, w, -w n , 3, -w, w, -w n , 4, -w, -w, -w n , 5, w, -w, w n , 6, w, w, w n , 7, -w, w, w n , 8, -w, -w, w e , 1, 2, 3, 4, 5, 6, 7, 8 /solu antype , substr     ! analy
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Reuse CMS Superelement in Ansys Workbench with Expansion

Figure 1: CMS Reuse Project Schematic In the previous two posts ( here and here ), the workflow requires another generation pass when reusing the model. This diminishes the advantage of using a component mode synthesis (CMS) superelement model. The difficulty is that when the model changes, the superelement node numbering no longer matches the new workbench (WB) model. Everything gets shuffled around. To reuse a superelement body, we need the  nodes to persist in the final Analysis for expansion. Strategy We start out with an original modal analysis ( Analysis A ) that would have worked on it's own. Next, the original modal analysis is duplicated (becoming Analysis B ). Analysis A will be modified to only have the superelement body while  Analysis B will be modified to have the geometry and mesh of non-superelement body. When both analysis are assembled into a new modal Analysis C , Analysis B 's element and nodes are automatically offset so that the ordering is
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Component Mode Synthesis (CMS) with Results Expansion in Ansys Workbench

Figure 1: Results from Full Model (Left) and CMS (Right) Background In a previous post on Component Mode Synthesis (CMS) in Ansys Workbench, the expansion of the results were omitted. This is remedied in this post. Figure 1 compares the results favorably between the full model to a model with the mid-section as a CMS part. Resources 1. The archived workbench file (R18) can be downloaded  here  (download icon at top-right). 2. Script that is used as solution snippet can be downloaded here . 3. A key resource is available in the help documentation . 4. Some fancy graphics describing the process here . General Setup Figure 2: Overall Geometry (Left) & CMS Part (Right) This example has a few prerequisites: 1. Multi-parts with shared topology  (Figure 2) 2. Named Selection of the CMS part (Body1 in example) 3. Named Selection of interface on CMS part (c1a & c2a in example) 4. Command snippet under solution does everything. Between steps, no suppressing and u
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Slice-and-Dice Mesh Selected Body

When meshing challenging bodies, it is sometimes useful to slide-and-dice bodies in SpaceClaim via Split Body and Share Topology  to isolate the trouble spots for tighter controls. In Mechanical, the bodies could be individually meshed in the 'right' sequence such that key features are respected. Figure 1: Generate Mesh on Selected Bodies This is done by first selecting the  Mesh object in the Outline. Right-mouse-button on the body, then Generate Mesh on Selected Bodies. This was done twice to generate bodies shown in Figure 2.  Figure 2: Individually Meshed Bodies
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