Modelling of an Automotive IP Trim component by using ANSA

PRE-PROCESSING OF INSTRUMENT PANEL SUBSTRATE ( DASH BOARD SUB PART ) OF A CAR USING ANSA

• Aim

The main aim of this project is to prepare the IP substrate for post-processing analysis. For that we have to do following operations

• check for the geometrical errors and perform geometry clean up
• Extract mid-surface of the component, we have to capture all small features present in the model like ribs
• Mesh the component with given element Quality criteria. We have to maintain good mesh flow
• After Meshing the component the thickness has to be assigned.

Dashboard

A dashboard (also called dash, Instrument panel (IP)) is a control panel usually located directly ahead of a vehicle's driver, displaying instrumentation and controls for the vehicle's operation. Dashboard is one of the main parts of the car interior component and plays a very important role in different aspects such as safety, reliability, user friendly, technology and appearance and so on.

• Procedure

Step 1: Open the IP model using File > open , and give an initial Topo operation for the entire component to paste the perimeters together so that the all the single cons we see while opening the model will become double cons.

To do this go to Topo Module > Faces > Topo, select the entire component with left mouse box selection and give a middle mouse confirmation.

In order to refine the perimeter of the model go to Mesh module > Perimeters > Length, select the entire model with left mouse box selection and confirm the selection with middle mouse click. Input the length value as 1 or 2 mm in the box and hit enter.

we can orient the faces of geometry using, Topo Module > Faces > Orient > visible, all visible faces will be oriented automatically, or we can select the specific face we want to orient.

Step 2 : Geometry check-up

Now we have to check for geometrical errors and perform geometry clean up

Go to Tools > Checks > Geometry > Execute

There are many geometrical errors present in the model like unchecked faces, cracked faces, needle faces, single cons, triple cons etc.

ANSA will fix most of the errors automatically, to do the automatic fix, select all the errors by Cntrl +A, and right-click on the selection and press Fix.

The errors that ANSA couldn't fix automatically will have to be fixed manually. For example to clear unchecked Faces error,

First, delete the unnecessary hot points by Topo module > Hotpoints > delete. Then delete the distorted face using Faces > delete option and create a new face using Faces > New option.

The most common cases when triple cons ( cyan colour) appear is when degenerate faces exist, we can solve this issue easily by deleting the degenerate face using

Faces > Delete option.

• IP model after clearing all geometrical errors

Step 3: Extract mid-surface

After fixing all geometrical errors and clean-up the geometry now we have to extract the mid-surface.

Since IP substrate is a plastic component it has varying thickness so we opt for Faces > Offset option and Faces > Middle option to extract mid-surface instead of Faces > skin option or automatic mid-surface option.

The main body of IP has a uniform thickness of 0.6 mm, so we use Topo Module > Faces > Offset option to extract the mid-surface.

Selection the face of main body with feature angle selection tool. So that only top or the bottom face is getting selected. Confirm with middle mouse click and input the off set value as half of the thickness as 0.3 mm. Thus a surface is created exactly at the middle.

we can assign new PID to the mid-surface extracted using Topo module > Faces > Set PID, select the mid-surface using left mouse box selection and confirm with middle mouse click. property window opens, right-click on the window and go to New > Pshell assign thickness of the part and press ok.

For other features like ribs we use Topo Module > Faces > Middle > single, option to extract the mid-surface. select the two faces of the ribs, we have to make sure that the two opposite faces are same to create a middle surface by Faces > Middle option. An imaginary plane will appear at the middle we can check the surface and accept the surface by pressing ok.

For features like cylinder we are representing it as 2D mesh, so we have to create surfaces passing through middle of the cylinder. In order to do that we are using

Topo Module > Curves > Cons2Curves option and select the cons that passing through the middle thus con will be converted to curves.

we can connect all the curves together into a single curve using Topo module > Curves > Connect > Multi and select all the curves parts with left mouse selection and confirm with middle mouse click.

Now we have to create new faces taking the curves passing through the middle as edges using Topo Module > Faces > New > coons.

We have to connect the mid-surface of ribs and cylinders to the main body of IP using Topo Module > Faces > Extend option

select the free edge of the ribs that has to be connected and confirm with middle mouse click and select the target face of the main body. Thus the free edge of the ribs will be extended to the target face forming a triple con.

Also we have to intersect the mid-surfaces which are connected each other using Topo Module > Faces > Intersect.

Select the first group of face using left mouse button highlighted in pink colour and similarly select the second group of face highlighted in blue colour and confirm with middle mouse click.

Thus we have extracted the mid-surface for entire IP model

Step 4: Meshing the mid-surface with given element quality criteria

Before meshing we have to defeature the areas where it's failing for minimum length in element quality criteria. For this we have to join cuts and perimeters using

Topo module > Faces > cuts and right mouse click to join the perimeters, left mouse button to create a new cut.

Input the element quality criteria and Mesh parameters

To generate mesh on the mid-surface go to, Mesh module > Mesh Generation > spot mesh, select the face needed to be meshed with left mouse click and confirm with middle mouse button. thus mesh will be formed on the selected face.

To check for element quality switch to hidden mode drawing style, available on the bottom toolbar.

As seen in the figure there are many failed elements , we can clear the quality of failed element using reconstructing the mesh,

Mesh module > shell mesh > Reconstruct select the macro-region where we want to reconstruct with left mouse selection and confirm with middle mouse button. we can re-run the algorithm in order to obtain a better mesh flow.

we can use Mesh module > Elements > Split option to eliminate the tria element present in fillets and free edges

Apply Mesh module > Shell Mesh > Smooth function after doing split operation in order to clear the element quality.

we can also use Elements > Split option to remove opposite trias present in the mesh. the figure below shows application of split option for removing opposite trias

applying shell Mesh > Smooth option to clear the failed element after applying split operation

we can also use Mesh module > Grids > Paste option to remove opposite trias by pasting the nodes to the element. The below figure shows the application of

Grids > Paste option in order to remove the opposite trias present in the mesh.

select the first node sets highlighted in white colour and confirm with middle mouse click and then select the second node sets highlighted in yellow colour.

figure below shows opposite tria elements are removed after applying paste option

• complete Meshed model of IP Substrate

we have to set different PID to the parts which are having different thicknesses and assign proper thickness value to each.

In order to represent the thickness assigned to the component go to Quality criteria ( F11 from keyboard) > in presentation parameters tab select Draw shell as solid option > Apply> ok.

Figures below show After applying draw shell as solid option

• Learning Outcomes
• Learned how to check for geometrical errors and perform geometry cleanup of complex plastic component.
• Learned how to extract mid-surface of complex plastic component having varying thickness
• Learned to mesh the component with given element quality and clear the quality of off elements.
• Learned to remove opposite trias and rotating quads present in the mesh also to eliminate trias from fillets and free edges thus maintaining a good mesh flow

• Conclusion

successfully extracted mid-surface of IP substrate model capturing all features present in the geometry and meshed the model with given element quality criteria.