Week 3 - 2D meshing for sheet metal

AIM:

• To do a pre-processing on a given hood model using ANSA.

OBJECTIVE:

• To check the geometrical error on the hood model.
• To extract a mid-surface on the components such as inner extract, outer extract, latch reinforcement extract and two hinge reinforcement extracts.
• To generate 2D mesh on the components based on the quality criteria given.
• Assigning thickness to the components.

INTRODUCTION:

CAR HOOD:

• The hood or bonnet is the hinged cover over the engine of motor vehicles. Hoods can open to allow access to the engine compartment, or trunk on rear-engine and some mid-engine vehicles for maintenance and repair.
• For sheet metal and plastic components which has thickness of less than 6-8mm. For that components a mid-surface should be extracted and pre-processed.

PROCEDURE:

IMPORTING THE CAD MODEL:

• The CAD model is imported into the workspace by using file > open and select the CAD model.
• The model will be imported into the workspace.
• In ANSA we can import all types of CAD software file formats.
• In the ANSA part list we can see that we have four component

1. LATCH REINFORCEMENT EXTRACT:

2. HINGE REINFORCEMENT EXTRACT:

3. OUTER EXTRACT:

4. INNER EXTRACT:

GEOMETRY CLEANUP:

• Before working on the model we need to check whether the model has any geometrical errors.
• To check the geometrical errors go to check manager that is available at the tool bar.
• In the check manager select geometry and click execute.

• After clicking on the check geometry the geometrical errors will display.

• The geometrical errors can be fixed manually or automatically.
• In our case we fixed the error automatically by right clicking on the error and click fix.

• Once the model has no error it will show green status in the above image and we can proceed further.

• Similarly the same process should be done for all the components.

MIDSURFACE GENERATION:

• For extracting we have two methods skin mid-surface and offset tool.
• In this case I used a manual offset tool to extract mid.
• To extract mid manually go to faces > offset

• Select the component faces and give the offset value and click middle mouse button.
• This will convert the solid model into a thin shell components.
• Then the mid surface is extracted by using AND and INOT tools available in ANSA
• The procedure is repeated for all the components to extract midsurface.

PROPERTY ID CREATION:

• Then the property id is created for the mid parts by going to set PID and select the surface and give the thickness value and click ok
• Then go to property id manager and right click the PID and click apply.

2D MESHING:

QUALITY CRITERIA:

• Go to quality criteria that is available in tool bar.
• The criteria that is given in the question are selected and given the value and clicked apply and ok.

• Then the values of mesh parameters are entered.
• For that go to mesh parameter tool that is available in the tool bar of ANSA.

• Then the meshing is done using mesh generation > best tool. This tool generates the mesh using the best algorithm applicable.
• Then the created mesh is refined using the shell mesh > reconstruct tool.
• It is ensured that there are no rotating quads.
• The trias are kept as low as possible.

LATCH REINFORCEMENT:

HINGE REINFORCEMENT:

OUTER EXTRACT:

INNER EXTRACT:

• Finally after creating the mesh and clearing the quality criteria the shell element representation is changed by going to utilities> quality criteria> presentation parameters and enabling the draw shell as solid.

• Draw shell as model will add thickness to the model with the thickness that is provided in property ID.
• Then the final model will look like the image as shown below.

RESULT:

• Hence the mid surface has been extracted from the parent geometry.
• Hence there are no surface deformations in the geometry.
• A well connectivity has been established between surfaces.
• The features have been captured properly.
• A good mesh flow has been achieved.

CONCLUSION:

Geometry cleanup, mid-surface extraction and 2D meshing of the given hood model were successfully done.