SHELL MESHING OF A CAR HOOD GEOMETRY USING ANSA V19.1.5

OBJECTIVE:

To mesh the given component as per the quality criteria given in the data and assigning thickness to it.

Quality criteria

PROCEDURE:

Geometry cleanup and Mid-surface extraction.

• A new .ansa file is opened and the .stp file of the given model is then imported on to the workpage.
• When imported the model (Hood), it contained lots of parts attached to it and each parts can be seperated out using the property option (control+P) from list.
• One of the part is choosen (Inner part) and its then viewed in ENT( entity mode) from drawing style to check for any orientiation issues (Top portion should be gray and bottom to be yellow in colour) and if there is any issues its then corrected using Faces>Orient(tool)>visible.
• Turn on the Cross-hatches form Face draw so that surfaces can be selected easily.
• Since most of the component have symmetricity (Checked using Faces>Rm.dbl), The meshing can be done to one of the half surface and then it been reflected to other side.
• The model is then subjected to geometry check up to find out any missing surfaces, free edges, duplicates etc. Tools tab>Checks>geometry>Execute.
• When check up was carried out, Ansa throwed out error messages, in which some of them can be fixed automatically and othes were done manually using other tools.
• After the cleanup the thickness of the model is been measured from different portions.
• Mid-surface of the component is extracted using Faces>Offest.
• Here Auto-mid-surfaceing can be done easily using skin option from faces. While using this option it should be noted that the part is fully closed.
• The extracted mid-surface from the part can be seperated out using not, i-not, neighb etc from focus toolbar.
• A new property for extraceted mid-surfaces is then then created using Faces>Set PID>New>P-shell.
• Rename the card and measured thickness is then assigned to it.
• The material is then defined by putting tick mark to the defined box. Other parameters such as youngs modulus, shear modulus, poissons ratio were also enterd, If these values were not entered the software won't consider it as a real object while running simulations.
• Due of symmetricity some of the surfaces were deleted as per the need.
• Splitting of the surfaces is done accordingly to avoid the failure of elements while meshing and also to get good flow over the mesh.
• These can be done using tools from topology and mesh modules. Join tool from mesh module can be used to toggle off unnecessary single cones.

Meshing.

• Meshing is done in mesh module and its turned on.

• The mesh parameter from untility is opened to enter the target element size, element type etc.

• Similarly the quality criteria option is also selected from the same toolbar and the values given as per the given data is then entered accordingly. From presentation parameter sub-option, check wheather the percentage element box is ticked also from detailed from demand effect drag the cursor towards all details.
• Now each splitted surfaces are meshed seperately using Mesh generation>Batch.
• While meshing its better to capture the surfaces with the given target element size for those in fillet regions it can be meshed with mininum element lenght.
• While meshing it resulted in creation of lots trias and rotational quads which can be again remeshed using Shell mesh> Reconstruct.
• Presence of trias in critical areas such as fillets, cut out regions are not preferable and it can be draged off using split, paste tool etc.
• The elements can be arranged uniformly using smooth tool from shell mesh option and while using this tool some of the elements gets displaced fron the splitted lines and these can projected on to those line using Grids>origin.
• Quality criteria applied can be viewed using Hidden view> Drawing styles, Where the elements gets highlated in diferent colours indicating the failures to respective criteria and correction has to be made further.
• After checking all the quality criteria, the half meshed portions are now reflected to other side using Utility>transform>copy.
• After reflecting the entities the connection between the two half portion of the surfaces can be made using Topo, Paste tool etc.
• Again all the criteria are checked and if any correction required its been done further.

• The thickness assigned to the model can be viewed using Utility>Quality criteria>Presentation parameter>Draw shell as solid.

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The same procedure were followed to mesh other components of the Hood.

• Save the file.

RESULTS:

The given model (Hood) is meshed sucessfully by following all the quality criteria given in the data and assigned thickness to it.

CONCLUSION:

From this challange, learned about geometric clean up, mid surface extraction, doing shell mesh, Assigning thickness etc.

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File:

https://drive.google.com/file/d/11Z17oSfqoaQfmtprIqy6qSANJ4QfWPWu/view?usp=sharing

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