ANSA- Hood Meshing

Objective: The hood model is used to extract a mid-surface, and is cleaned to extract an FE model based on the quality criteria specified.

The model provided is a sheet metal model, and hence will be modelled into shell elements.

Stage 1: Extraction of Mid Surface Skin

The inner and outer hood is used to extract the mid surface. This done using the Mid Surface or Offset command.

The edges can be modified if necessary, for mid-surface extraction. The surface that is to be used to create the skin is selected and all appropriate options selected to obtain the mid skin.

The Mid-Skin is created into a new property which is named as “Outer Hood Skin” or “Inner Hood Skin” accordingly. The property is edited to ensure that the element type, thickness and other parameters are set appropriately. It has to ensured that Nastran is selected as the solver.

Stage 2: Geometry Simplification

The part of the model where overlap occurs, only one surface is retained and the overall thickness is assigned to that surface.

The portion where the outer panel sheet metal is hemmed over the inner panel is to be made into a separate property with an overall thickness of 2.25mm (2*0.75 + 0.75).

The entire CON loop shown below is projected onto the inner hood skin surface.

The same loop is also projected on the outer panel’s opposite surface.

After the CONs have been projected, the outer panel’s hemmed portion is deleted as shown below:

Then the inner panel’s portion that is under the hem is also deleted as shown below:

Now the single CONs on the inner panel edge is pasted onto the double CON of the outer panel (that was previously projected), creating a triple CON.

This triple CON separates the hemmed portion of the outer panel from the rest. A new property is created for the hemmed portion with a thickness of 2.25mm

From the model, it can be measured that the Hinge and Latch reinforcements have a thickness of 1.2mm. This can be simply added onto the inner panel in the region where they coincide with it.

The border CONs of the hinge reinforcements are projected onto the inner panel surface as shown below:

The hinge reinforcement surfaces are then deleted and the Property is assigned to the region projected onto the inner surface with a thickness of 1.95mm as shown below:

This process is repeated for others also, completely simplifying the geometry.

Stage 3: Meshing

Stage 3: Meshing

The completed model is meshed using the guidelines provided. All the conditions of the mesh are input into the Quality Criteria as shown below:

The entire model is meshed using an appropriate algorithm.

All the errors are worked on in the hidden mode using tools like Reconstruct, Split, Swap, MV Surface, MV Free etc. can be used until the quality criteria has been attained.

Finally the FE Mesh is extracted using Elements> Release. Only the FE elements are retained and the CADD model is deleted.

Result:

The final FE Model can now be used for FE analysis and it satisfies all the required quality criteria.

Drive Link:

https://drive.google.com/open?id=1Geru0ssz6mb7FcZ3vYm2G4MhQZt_GpMx