Week 4 - 2D Meshing for Sheet Metal

Objective:-

The 2D meshing of Sheet metal as given Hood Inner Panel with the below-mentioned quality criteria and features.

S.No	Quality Criteria	Value
1	Target/Average length	5
2	Minimum Length	3
3	Maximum Length	7
4	Aspect	3
5	Warpage	15
6	Skewness	45
7	Jacobian	0.7
8	Minimum Quad Angle	45
9	Maximum Quad Angle	135
10	Minimum Tria Angle	30
11	Maximum Tria Angle	120
10	Tria Percentage	15

CAD Model:-

The Below-mentioned CAD model is taken for 2D meshing.

Procedures:-

1. Open Ansa Software using Start->All Apps->Beta CAE Systems->Ansa Vxx. x.xx With Performance Mode 3 on Launch Screen
2. Import CAD File Using File->Open. After importing it looks like the above image 1.
3. Checking the CAD surface finish by Panning across the Model and increasing the resolution of the Model by using Perimeters->Length in the Classic Mesh menu. select the model and give a perimeters value is 1 and a macro's value is 1and give a middle click to End-up.
4. Giving Topology to the model by using Faces->Topo in the Modules Manubar.
5. Check the Geometry of the Model using Checks->Geometry in Tools Menubar. and ensure the below comments are selected and executed in the Checks Manager Window.
6. If any errors or Geometrical problems are available in the model as in the above image. Select the Errors by using CTRL+A and select the Fix Comment in the Right Selection Menu, Ansa will fix the issue automatically. if any errors are not fixed automatically by Ansa as in the below image then fix the issues manually.
7. Find the Geometry issues with selecting the error in the Checks manager and use Show only comment in Right Selection Menu. it shows the issue in the Model and then uses "AND" Boolean Operation to show related Faces to the Issues as like below.
8. Use "Or" Boolean Comment with PID Region Mode in Feature Selection Menu. Select one Component and Delete the Extra cons in the component by using Cons->Release and providing Topo Convert single con into double con by using Faces->Topo. Repeat the Same operation for the Triple Cons issues across the Model. issue resolved as below.
9. If now we run Checks Manger it Shows 100% fulfills the requirement as like below.
10. Improve the CAD surface orientation by using Faces->Orient->Visible. It changes as a high ratio orientation is available in actual CAD Surfaces.
11. After the Geometry requirements are fulfilled then go for mid-Surfacing by using the below method.
• Select one Component among the model using "Or" Boolean Operation with the help of the PID Region Selection Tool in the Feature Selection Menubar and ensure the component is completely closed by panning.
• Create Mid-surface automatically by using Faces->Mid.Surface->Skin. And give a middle click to complete the operation. it will automatically generate the mid-surface and also provides Thickness to the Mid-Surface.

1. Mesh Preparation:-
• First, hide the component in the Mid-surface area by using "Not" Boolean Comment with PID Region selection mode. Now only the Mid-surface only visible as below shown image.
• Use Hot points->Insert comment in the Classic Mesh Menu to remove the extra hot point available in the Mid-surface using the area selection with the right mouse click.
• Give the perimeters length value into 5 for the mid-surface using Perimeters->Length and provide the length value as 5.
2. Performing Mesh Operation:-
   • Set the Quality Criteria for the meshing by pressing the F11 key on the Keyboard it shows the Quality Criteria window, Provide the following details as given as a task or in objective as shown below.
   • Press Apply it applies criteria to the Mid-surface then Press OK.
   • If going for Shadow Mode in Drawing Style Menu the criteria are visible.
   • To feed the Mesh Parameters to Mid-surface by using Mesh Parameters in the Utilities Menu provide the values as shown below. then complete the operation by Press OK in the mesh parameter window..
• Check the Whole area by panning and also ensure the perimeters available in the Holes are Even Numbers by using Perimeters->Number and the Cons in the holes it shows the No of perimeters available in the Hole.
• perform this operation to ensure all Holes have an even No of Perimeters
• Now we can move to the mesh generation by using Mesh Generation->Best->Select. Select the first mid-surface completely and end the action with a middle click.
• Now we can see quality Criteria errors in using the Shadow mode. by Changing the Mesh pattern to remove or avoid these errors by pressing Shell Mesh-> Reconstruct->Select. Select the Meshed Area & press the Middle click to Complete the selection, Ansa process and gives the better Mesh and reduces the Quality Errors.
• To avoid Quality errors by using Elements->Swap, and Elements->Split to reduce the errors.
• Also, use Shell Mesh->Smooth option to smoothen the mesh
• Perform all the above steps to ensure all Mid-surfaces mesh and also there are no quality criteria errors across the surface as below.
• Perform Operations 11 to 13 for all other components to complete the Mesh Generation for the Overall Model.
• Finish Operation and the save the File.

Result:-

As per the requirements we did the Geometry Cleanup, Topology, Mid-Surfacing, and Mesh Generation with all ensuring Quality Criteria as given in the Objective for the Hood Inner Panel as a 3D Model.

Final Result Image:-