Challenge

2D Meshing of Hood Model With HyperWorks

AIM:

2D Meshing of the Hood Model as per following quality criteria.

PROCEDURE:

(1) Import:

Initially the given model is imported using import geometry option

Once the file required is browsed and imported, the model is displayed as follows:

The hood model is developed by using 5 different components as shown below:

Midsurface extraction,Geometry Cleanup and meshing of each components are done seperately.

(2) Mid-surface Extraction:

Each component is selected once to extract the midsurface.
Before creating the mid surface, solids within the component should be deleted by using the delete tool with solids as selection criteria.
After solids are deleted from the part, mid surface can be generated by using midsurface tool under geometry tab.

Once the mid surface is generated, new component named midsurface will be generated in the tab area under model tab along with the other components.
The new component is renamed according to the hood part under consideration.

Similarly midsurfaces of all the components are extracted and saved as different components.

(3) Geometry Clean-up:

After the mdsurfaces are extracted from the model, before meshing the mid-surface, geometry clean up of the surfaces are done.
Geometry cleanup is done using autocleanup tool under geometry tab
Clean-up will remove connectivity errors and restore the surface data to a perfect representation of the part.

After geometry cleanup is performed, additional edges as required are created and unwanted edges are toggled using quick edit tools (toggle edge, split surface) under geometry tab.
Larger surfaces are further divided to smaller surfaces for proper meshing.

(3)Meshing:

After the cleanup is finished and each component is divided into smaller and simple surfaces to obtain proper mesh.
The meshing is done by using automesh tool under 2-D tab with elements size as 5 and element type as quad.
The meshing of each component is done surface wise from one small surface and is progressed into adjacent attached surfaces.
After each small surfaces are meshed, quality criteria check is carried out inorder to clear any criteria violating elements at early stages itself.
Criteria check is done using qualityindex tool and check elems tool under 2-D tab.
Under check elems tool, quality criteria is set as follows:

After criteria is defined, the meshed elements of all components are checked using qualityindex tool.

The elements violating the specified quality criteria are marked yellow and red.
Cleanup tools like element optimize and place node within the qualityindex is used to optmise the violating elements.
For elements which are not optimized to within the criteria range with qualityindex tool, elem cleanup tool is used.
In situations where qualityindex and elem cleanup tools failed to rectify the violating elements, automesh tool is used to remesh the non-optmized elements.
The elements of the all components are checked if any more violating elements are present.
If present, the above steps are repeated until all elements fall under the given quality criteria.

(4)Element Checks:

Edges
After meshing of components, at some areas the connectivity between elements where found to be disturbed hence forming free edge within the model which is not desirable.
Following figure shows a situation where a free edge was formed within the component rather than on the outside edges.

Inorder to remove these free edges, the edges tool in tool tab is used.
All the elements of the component are selected and find edge option is selected.
This finds and creates a free edge component which depicts where all free edges are present.
If any free edges are formed at undesired areas as shown above, elements near to these edges are selected, preview equivalence option is selected.

After preview equivalence option is selected for the selected elements, nodes between the elements that are disconnected causing free edges are displayed.
Then equivalence option is selected with desired tolerance value which will connect the nodes between disconnected elements.

After equivalence is done, again find edges tool is used by selecting all the elements.
The same process is carried out for all the components to remove any undesired free edges or element disconnectivities.

Element Normal:
Normal tool from the Tool tab is used to review the direction of normal of all the elements of the component.
The normal of all the elements should act in the same direction.
For elements which are not in the same direction, these elements are selected and reverse option is used under the normal tool tab.

Each component is checked for normal and if variation is found, the same is corrected.

Comparison - elements to surface
Comparison tool is used to check the connectivity of elements to the surface of the components.
Initially the elements in the component is selected, then the surface to review connectivity is selected and comparison test is run.
If any unmatched elements are observed (red), then the project tool under tool tab is used to project the unmatched elements to the desired surfaces.

Finally after elements of all components are checked, all elements are selected and qualityindex tool is used to ensure there are no criteria violating elements.

(5)Assigning Thickness:

Initially Material and property for each component is created under the tab area.

Card image for material selected is MAT1 and for property is PSHELL for all the components.
A thickness of 2.5 is also assigned under the property.
After property and material is created and defined as desired, this property is assigned to each of the component created.

CONCLUSION:

Mid-Surface is extracted for each component seperately and meshing of the hood model is performed with elements having quality criteria within the given range.
Different properties for each component is assigned and thickness is also assigned for the elements.

Ship work like this
in your own course.