HYPERMESH-Week 6-Meshing of Hood Challenge

AIM: To create a Mid-surface for given components & to mesh them in a good-looking manner of the element size of 5mm, ensure the given quality criteria were satisfied.

Quality Criteria need to be Satisfy:

S.N	Quality Criteria	Value
1	Aspect Ratio	5
2	Skewness	45
3	Warping	15
4	Taper	0.5
5	Min. Length	2 Units
6	Max. Length	8 Units
7	Min angle Quad	45
8	Max angle Quad	135
9	Min angle Tria	20
10	Max angle Tria	120
10	Tria %	10

To assign the value of the given Criteria "Preferences -> Criteria Files -> Input the values"

The Below, pictures show that all components are having separate Midsurfaces

Procedure:

Import the model by using the "Import Geometry" option, ensure all the components are available as per the requirement before making taking the Mid-surface/ AutoMesh option,

There are 4 Components present in the Hood model:

• Latch
• Hinge
• Outer Body
• Inner Body

Before Extracting the mid surface, if solids are available in the model are need to be deleted using the "Delete" Option by selecting Solids in it.

Select the Solids to be deleted, then click delete entities.

Creating of Mid-Surface:

To create a Midsurface on the component we have to choose " Geom -> Midsurface -> Extraction options -> Offset+Planes".

The midsurface is already extracted in the image below using the Geometry tool.

Below the Image is an extraction of the Inner Extract body.

Once the extraction of the Mid-surface in the Model, Now turn off the Surface of the Inner extract body to show up the mid-surface of the model.

Geometry Cleanup:

Now do the Geometry clean-up "manually" or by "AutoCleanup" to clear up the unwanted Line in the geometry in it.

To clean the Components manually use the Quick edit panel by pressing F11, Using "Toggle" unsplit the unwanted line in it.

Once the Clean-up did, Now it's time to Create a Mesh on the mid Surfaces.

The toggle edge tool is used to suppress unwanted edges as shown in the picture below. The dotted blue line is suppressed so that a proper mesh can be achieved.

To remove unwanted points the add/remove point and the replace point tools are used. To use the add/remove point tool, the point that has to be removed is right-clicked and if we want to add a point a left click is done. To use the replace point tool, the point that has to be replaced is selected first followed by the point that will be retained.

When there are cutouts in the surface a washer split is added so that the surface can be better captured when meshed. The offset value is given as 4. In the picture below the washer split is used on all the cutouts and in some more than once to improve the mesh quality.

To create a midline to reflect the mesh in that component we have to generate a midpoint in it.

Using "Split Surf line"

Meshing:

To do Mesh on the Component " 2D -> Automesh -> Select the area to be mesh "

To mesh the auto mesh tool in the 2D tab is used which can also be accessed by pressing the F12 key.

The element size is changed to 5 and the mesh type is chosen as mixed and the surface to mesh is selected.

The meshing of the surface is done in batches so that proper changes in the number of nodes and quality checks can be done with much less difficulty.

When meshing if a tria element is formed it can be removed by either increasing or decreasing the number of nodes under normal circumstances when the surface doesn't have extreme curves.

In some cases when a proper mesh is not attained in such that case we can use "Remesh" Option so that instead of remeshin the whole components by using the "Remesh" option we can built a good mesh flow by the selecting the region that has to be meshed.

The elements are selected in a way that they form either a square or a rectangle or any closed figure so that a better mesh can be obtained. The selection is shown in the picture below.

In the pictures below, we can see that the meshing is done in batches.

Due to the component which is shown above is symmetry we can construct half of the geometry for meshing and then using an auto mesh option the mesh can be created.

To reflect the component once the meshing is done to the model "Tool -> Reflect -> Select Elems -> Duplicate -> choose the base point" before that make the model as the current component or else the main components will get reflected it.

Meshed components:

Inner Extraction:

Outer Extraction:

Latch Extraction:

Hinge Extraction:

Quality Index:

After re-meshing, to improve and check the quality of the mesh the 'qualityindex' tool in the 2D tab is used.

Elements that are highlighted in yellow and in red are not acceptable and have to be rectified.

The 'element optimize', 'drag tria element', 'place nodes', 'split quad elements', and 'combine tria elements' are the heavily used cleanup tools.

The 'drag tria element' is used to move the tria elements in the mesh, two opposite trias can b moved together so that they form a quad element.

The 'place nodes' tool is used to move the nodes of the element so that their shape can be changed or slight adjustments can be made.

The 'split quad element' tool is used to split a quad into two trias, this is useful because the trias can be used to form quads in other places.

The 'combine tria elements' tool is used to combine two adjacent tria elements, but this can also be achieved by using the 'drag tria element'.

The combined tria element may not satisfy the quality criteria that we have specified and if it doesn't it will be shown in yellow or red as shown in the above picture. This can be easily rectified using the 'element optimizes' tool. In some cases using only the 'element optimize' tool will not work, in those cases, the 'place node' tool is also used to change the position of the nodes and hence the element shape.

After all the elements in yellow and red are rectified by using the cleanup tools or by re-meshing, the 'check elems' tool under the Tool tab is used to check the elements for all the quality criteria individually.

Quality index:

To Check the quality of the index of each component are done and pictures of all quality checklist of images are given below.

Inner Extract:

Outer Extract:

Hinge Extract:

In the above images, we can see that all the quality criteria are satisfied for all the mid surfaces except for the outer_extract, this is because of the elements in the Hemming region.

Hatch:

Final Mesh:

Hatch:

Latch:

Result:

The given component are been mesh will according to the given criteria, and the quality of the meshes are been checked by the quality checks.