Project 1 - 2D meshing on the instrumental Panel

OBJECTIVE:

To extract the midsurface and perform meshing on the instrument panel by following the given Quality Criteria’s and also to assign the corresponding thickness.

PROCEDURE:

MODEL – 1 :

1) Open the given model in ANSA.

The surfaces in the model are not stitched together as can be seen by the presence of the single cons(red lines). By using the ‘Topo’ function, topological conditions between the adjacent CONS can be created automatically.

2) Geometry Cleanup

Before extracting the mid surface from the model, it needs to be ensured that the model surface is perfect and free from errors like free edges, cracks, overlap faces, distorted faces, needle faces etc. The geometry check is done using the Checks Manager available under, Tools>Checks>Geometry.

ANSA provides an option to automatically rectify the errors. This is done by, selecting all the errors>rigiht click>Fix. If any errors persist then it can be fixed manually.

3) Mid surface extraction

Before extracting the Mid surface, the thickness of the component has to be measured.

On measuring the thickness of the base surface at different locations on the component, it is found to be having a uniform thickness of 0.6 mm.

Hence, the mid surface of the base is extracted by using the ‘Offset’ option. Under Faces>Offset, the top or bottom face is selected using the ‘Feature Area’ selection tool. The face is then offset by a distance equal to half the thickness of the component (0.3 mm).

New PID is created for the mid surface and the corresponding thickness of 0.6 mm is assigned.

For other sections such as the ribs, the mid surface is extracted using the ‘middle’ option.

Faces>Middle

The dog houses are captured as Cross Pattern in the midsurface. This is done by first taking mid surface for the ribs associated with the dog house and then extending or intersecting or by creating a new surface between the rib mid surfaces.

For dog houses where the above method is not possible, the mid surface is extracted as follows. A curve is created through the middle of the dog house surface by using Topo>Curves>middle option. This curve is then used to create the midsurface using the Faces>New>COONS option.

The corresponding thickness are assigned to all the newly created mid surfaces.

4) Meshing of midsurface

Batch meshing is performed on the base surface using the ‘Batch Mesh’ tool. It needs to be ensured that the quality criteria’s and the meshing parameters have been defined.

After updating all these values, click on the Run button to generate the Batch Mesh. For the ribs and dog houses manual meshing has been performed.

5) Ensuring proper mesh flow and quality of elements generated

The generated mesh is examined properly to ensure that there is a proper mesh flow. Also, the number of trias should be kept to a minimum. Ensure that there are no rotating quads, back to back trias, opposite trias or trias on feature line. The various tools available such as Reconstruct, Split, Swap, and Paste can be used for this purpose.

Check if any elements are failing for any of the given quality criteria’s. If any element is found to be failing the given quality criteria then the required cleanup is done to correct them. The ‘Reconstruct’ option under ‘Shell Mesh’ can be used to improve the mesh. It examines a given mesh and performs re-meshing to correct problematic areas and optimize the overall quality of the mesh according to the mesh parameters. Smoothing is performed using the ‘Smooth’ option under Shell mesh to improve the mesh flow after performing any operation.

There are some failed elements near to Triple CONS or at smaller regions which are bounded by two Triple CONS which cannot be removed due to feature capturing.

6) To view the 2D shell elements as solid based on their PID thickness,

Quality Criteria>Presentation Parameters>Draw shell as solid

FINAL MESHED MODEL IMAGE:

LEARNING OUTCOMES:

• Learned how to perform geometry cleanup and extract midsurface for a plastic component having varying thickness.
• Gained understanding on how to perform meshing and obtain good quality mesh and proper mesh flow using the various tools available in ANSA pre-processor.

CONCLUSION:

The given components were meshed according to the given quality criteria’s after extracting the midsurface. Also, the required thickness was assigned to the elements.