Batch Mesh

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<p>Tutorial</p> <p>BATCH MESHSHELL MESHINGTable of Contents1. Introduction....................................................................................................................................2 1.1 Prerequisites............................................................................................................................2 1.2 Problem description..................................................................................................................2 1.3 Data files..................................................................................................................................2 2. Read and prepare the geometry.....................................................................................................3 2.1 Read and merge the parts........................................................................................................3 2.2 Check Geometry......................................................................................................................4 3. The Batch Mesh Manager...............................................................................................................6 3.1 Create the meshing scenario...................................................................................................6 3.2 Set the meshing parameters....................................................................................................7 3.3 Define quality criteria..............................................................................................................14 3.4 Keep important features.........................................................................................................15 3.5 Run Batch Mesh and view statistics.......................................................................................18 4. Mesh improvement........................................................................................................................19 4.1 Check mesh quality and correct violations.............................................................................19 4.2 Check and correct Penetrations.............................................................................................22 5. Conclusion....................................................................................................................................23</p> <p>BETA CAE Systems S.A.</p> <p>Shell Meshing using the Batch Mesh Manager 1. IntroductionThe scope of this tutorial is to guide the user through the basic functionality of the Batch Mesh Manager in order to automatically mesh a model specifying the necessary meshing parameters and quality criteria. The tutorial mainly focuses in understanding why and how the meshing parameters must be set, according to the size and shape of features in the model, to get the best possible result. The steps described in this tutorial are: - Merge the ANSA databases containing the geometry - Check geometry - Create the meshing scenario - Set the parameters and quality criteria - Run the batch mesh - View statistics - Manual mesh improvement and final checks ! Note that the results that you will produce by the Batch Mesh may have some small variations compared with those presented in the pictures of this tutorial.</p> <p>1.1 Prerequisites It is highly recommended to have read the Introduction &amp; getting started document as well as to have performed the basic ANSA tutorial or to have basic meshing background. Also, User's Guide paragraphs 12.1 and 12.2 give a brief overview of the Batch Mesh Tool. Theafter_batch_mesh_practices.pdf document explains how the mesh can be improved after running the Batch Mesh. 1.2 Problem description The model, a half frontal rail structure, consists of five parts saved in separate databases which need to be merged in one. Then the geometry must be checked before being meshed by the Batch Mesh Tool using a global element length of 8mm. The meshing parameters must be set in a way that the resulted mesh will only need minor manual improvements in order to fulfill all the defined quality criteria.</p> <p>1.3 Data files The files required for this tutorial are CrossLower.ansa, CrossUpper.ansa, Reinf.ansa, SideMemberInner.ansa and SideMemberOuter.ansa. The result file is batch_mesh_result.ansa. Also the mesh parameters and quality criteria can be found in 8mm.ansa_mpar and8mm.ansa_qual respectively.</p> <p>BETA CAE Systems S.A.</p> <p>2</p> <p>ANSA v.13.x Tutorials</p> <p>Shell Meshing using the Batch Mesh Manager 2. Read and prepare the geometry2.1 Read and merge the parts Start ANSA and create a new empty database from File&gt;New (Ctrl+N). Then, select File&gt;Merge to open the File Manager.</p> <p>Navigate and select all the files from Parts_To_Merge directory. Click on OPEN.</p> <p>In Merge Parameters window leave the default settings and press OK.</p> <p>BETA CAE Systems S.A.</p> <p>3</p> <p>ANSA v.13.x Tutorials</p> <p>Shell Meshing using the Batch Mesh ManagerOpen the Part Manager (Ctrl+R) and switch to Icon View. You can see the five merged Parts and an empty one named untitled which has to be deleted.</p> <p>To do so, right click on it and select delete. Confirm and close the Part Manager.</p> <p>2.2 Check Geometry It is highly recommended before meshing the model to correct any geometrical problems which may exist. Firstly, you must change the CONS resolution to equal the target element length of 8mm. To do so, activate the Windows&gt;Options (Ctrl+I). Under the Settings, in Resolution, change the CONS Resolution to 8. Press APPLY, confirm and close the window. Having all parts visible, activate from the D.UTIL group the CHECK&gt;GEOMETRY. Select all checks except the Unmeshed Macros and Single Bounds and confirm.</p> <p>The check shows in green that there aren't any geometrical errors present.</p> <p>BETA CAE Systems S.A.</p> <p>4</p> <p>ANSA v.13.x Tutorials</p> <p>Shell Meshing using the Batch Mesh ManagerYou must also check that single (red CONS) bounds are present only at the edges of each part and where holes are present. Deactivate from the Visibility group the SHADOW, DOUBLE and HOT PNT flag buttons.</p> <p>To visually check the Parts one by one, open the Part Manager and right click on each one and select show only. You can confirm now that there no boundary problems. When finished, activate SHADOW, DOUBLE and HOT PNT flag buttons.</p> <p>Finally you can check for intersections by activating from the D.UTIL group the CHECK&gt;PENETRATION&gt;INTERSECTIONS Click OK on the dialog to start the check. There are no intersection errors.</p> <p>! It is very important to have a model free of geometry errors before meshing it to get the best possible results. Geometry or intersection errors depend on the CONS resolution. Always check in resolution same as the target element length or finer. Now you can proceed to the meshing process.</p> <p>BETA CAE Systems S.A.</p> <p>5</p> <p>ANSA v.13.x Tutorials</p> <p>Shell Meshing using the Batch Mesh Manager 3. The Batch Mesh Manager3.1 Create the meshing scenario Open the Batch Mesh Manager by clicking to its shortcut icon or by WINDOWS&gt;BATCH MESH (Ctrl + B) Create the meshing scenario by New&gt;Meshing Scenario. The default session is automatically created. As all the parts are going to be meshed using the same parameters, no additional sessions need to be added.</p> <p>The next step is to load the five parts into the meshing scenario. Double click on 0 in the Items column. The Contents window opens. 2X</p> <p>As you are only going to use the default session all parts will be added there. Select all parts from the Pending Items list by clicking on the select All button and move them in the Meshing Scenario list by pressing the green arrow. Confirm and close the window by pressing on OK. All parts are automatically loaded now into the default session.</p> <p>Note: In case that more sessions and filters were created, the parts would automatically be distributed to sessions according to these filters. See 12.3.7 of ANSA User's Guide.</p> <p>BETA CAE Systems S.A.</p> <p>6</p> <p>ANSA v.13.x Tutorials</p> <p>Shell Meshing using the Batch Mesh Manager3.2 Set the meshing parameters The main and most important setting in the meshing parameters is the target element length. In addition, there are settings concerning the treatment of various features like holes, flanges and fillets. In order to correctly set up these, it is obligatory to know the violating limits of each quality criterion for the mesh that will be generated, especially the minimum and maximum element length. It is already mentioned that the target element length is 8mm. The quality criteria to be used are the following: Aspect Ratio Skewness Warping Min Length Max Length Min Angle Quads Max Angle Quads Min Angle Trias Max Angle Trias NASTRAN PATRAN IDEAS IDEAS IDEAS IDEAS IDEAS 3 45 12.5 5mm 15mm 60 120 30 120</p> <p>For more information on quality criteria definition see ANSA User's Guide 10.5.1 To edit the Mesh Parameters, which are currently named Untitled, double click on their name under the Mesh Parameters column. Alternatively, you can right click on it and select Edit &gt; Meshing Parameters. 2X</p> <p>The Mesh Parameters Window opens with all options set to default values. On top, in the Name field optionally type 8mm. You can see that the parameters are divided in tabs; the Shell Mesh, Defeaturing, Fillets, Flanges, Holes, Tubes and Fix Quality tabs.</p> <p>BETA CAE Systems S.A.</p> <p>7</p> <p>ANSA v.13.x Tutorials</p> <p>Shell Meshing using the Batch Mesh ManagerIn Shell Mesh tab, by default, the type of mesh is configured as General, Mixed with 1st order elements. The target element length is automatically set to 8mm taken from the CONS resolution. Distortion distance and Distortion angle are set by default to 20% and 0 respectively. None of the options under Remove triangle from: is active. Make sure that all these settings are set as shown in the picture on the left. Also, in the Defeaturing tab leave all default settings making sure that the Defeaturing level is set to fine and the Join perimeters with distance PENETRATIONS&gt;PROPERTY THICKNESS Leave the factor to one and press ENTER to start the check. Intersections and penetrations are found. Select them and press Show Only to see them.</p> <p>For information and guidelines on how to fix intersection and penetration problems refer to ANSA User's Guide 10.8.3</p> <p>BETA CAE Systems S.A.</p> <p>22</p> <p>ANSA v.13.x Tutorials</p> <p>Shell Meshing using the Batch Mesh Manager 5. ConclusionThis tutorial presented shortly the most commonly used shell meshing scenario using the Batch Mesh manager. It was shown how the model should be prepared before meshing and how to set the meshing parameters and the quality criteria. The case where different mesh density is needed for different model areas by the addition of more meshing session it was not presented as for each one, the same techniques can be used. Other features like setting ranges in the quality criteria can always be studied using ANSA's User Guide chapter 12. Finally, some techniques for the mesh improvement and the checks to be performed after meshing were referred. For more information use after_batch_mesh_practices.pdf document and ANSA's User Guide 10.6, 10.7 and 10.8.</p> <p>BETA CAE Systems S.A.</p> <p>23</p> <p>ANSA v.13.x Tutorials</p>