Week 6- Challenge

Objective:

• To mesh the given Hood component using given Quality criteria and assign thickness

Target Element Length = 5mm

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

Case setup and execution:

• Geometry cleanup

The given Housing/Plastic component 3D CAD model is imported into Hypermesh and is checked for CAD errors using visualization tool. Change visualization to “By Topo” and switch to wireframe mode to view the status of each edge.

We also see some edges on the model which are very close to each other and would create problems while meshing (elements would fail because of minimum element length requirement). Toggle unnecessary edges using

Geometry -> Quick Edit -> Toggle edge

In these components, we can see areas where edges are very close and would eventually fail quality criteria if meshed. So, it is better to toggle these edges.

We can also use Auto Cleanup option to clean the geometry

Geometry-> Auto Cleanup

• Mid surface creation

Midsurface is generated for the plastic part using

Geometry -> Midsurface -> Auto Midsurfacing

• Meshing

There are 4 components in the Hood model, and we will mesh them individually using the quality criteria provided

Target Element Length = 5mm

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

First, a washer split is created on holes and outer edges to have only quads on edges. Then the other surfaces are automeshed using 5mm as target length and in the automesh option, flow – align and size are checked.

2D -> Automesh

Symmetric components are split into two along the symmetric line. Only one surface is meshed and the other surface is meshed by duplicating and reflecting the elements on the meshed surface.

Inner extract, Outer extract, and Latch reinforcement can be meshed using this approach

The middle slot along with the surface can be initially omitted and then can be meshed after both sides of the symmetric surfaces are meshed.

Some of the commonly used commands

Geometry -> Node edit -> Align

2D -> Smooth

2D -> mesh edit -> Split

2D -> mesh edit -> combine

Tools -> Reflect

Tools -> Project

Commands under 2D -> Quality Index

Node optimize

Element Optimize

Place Node

Split quad into trias

Combine trias to quads

Drag Tria

These tools are used to make sure the following criteria are satisfied

1. No rotational quads
2. No trias pointing opposite to each other
3. Mesh flow is smooth
4. No trias on edges of the midsurface
5. Elements pass the quality criteria provided

Checks

Tools -> normal

To ensure all the element normals from one side of the surface point in one direction

Tools -> Penetrations

To ensure there is no penetration of elements

Tools -> Dependency

To ensure there is no element dependency

Tools -> Edges

To check connectivity of elements. If there are disconnections, equivalence it

Menu bar -> Mesh -> Checks -> Comparison – to check how well the meshes match with the surface

Finally, after performing the above mentioned procedure for all the 4 components in the Hood model, the quality of the mesh is checked using

2D -> check elements

Then common material Steel is created and properties are created for each component individually with the respective thickness