Project - 2 - Meshing on the suspension Assembly

Aim- For the given assembly, check for the geometrical errors and mesh with the given element Quality criteria. After meshing the component the thickness has to be assigned for mid surfaces. Use tetra elements to model non-uniform thickness components. Also use Appropriate connections to connect the component as suggested in the Project-2 video.

Quality criteria-

PROCEDURE:

Step 1: Import the geometry into ANSA and do topo to stitch the surfaces. Isolate each part and set PID’s for the rear suspension geometry.

Step 2: Clean the geometry using checks manager. Enable unchecked faces, collapsed cons, triple cons, needle faces, overlapped faces, cracks, single cons. Clear all these issues until no error is found. One can use fix option in ANSA to clear all the errors automatically. However, sometimes manual intervention is required for fixing some errors. Manually we can use options like cut, release and delete for topo clean up.

Surface Mesh Generation for Tyre and Rim

• One can do mesh generation for tyre and rim either by meshing them manually using spot mesh or by batch mesh.
• The advantage of batch mesh is that ANSA will do topological clean up automatically which is a time saving process. Even though sometimes we must clear some errors manually after batch meshing also.
• Mesh generation using Batch mesh option. The 1^st step is to create a new part in the model browser and assign the mid surface to that new part. Then open the batch mesh and create a new meshing scenario.
• Update the content i.e. the mid surface and the required mesh parameters and quality criteria. Then click on RUN to generate batch mesh.

Volume Mesh Generation for Tyre and Rim

• After clearing all the off elements on the surface mesh one can proceed further to volume mesh generation.
• Volume mesh can be created in ANSA only if it recognizes the geometry as a closed volume. Therefore, we must manually update our model to closed volume.
• To convert our model to closed volume one must define volume.
• ANSA might crash if you generate volume mesh for the whole geometry. So, define individual closed volumes for different PID’s.
• Defined volumes can be checked under list option under volume dialog box.
• One can give either Tetra Rapid or Tetra FEM under unstructured mesh dialog box for closed volume.

Mid Surface Generation for sub frame and macpherson strut outer surface

• casting option for generating mid surface for sub frame and macpherson strut outer surface.
• The advantage of using casting is that ANSA generates mesh along with the mid surface. Don’t forget to assign the given quality criteria for mid surface.

Surface mesh generation and volume mesh generation for remaining parts

• For Remaining all parts, I have generated batch mesh by isolating each part individually.
• After generating batch mesh clear off elements manually.
• Trias or ortho-trias are used as surface mesh for volume generated parts.
• After surface meshing, define closed volume individually for each part in Nastran deck.
• Now, a list of volumes will be shown in the list dialog box. Generate volume mesh either by tetra rapid or tetra FEM.

Connections for rear suspension

• After completion of mid surface and volume mesh we must connect them by using connections like bolt connection, spot weld connection, seam weld connection etc.
• Bolt connection can be generated using RB2 option in the Nastran deck.

Cluster or Spider RB2: This connection is used when a manual bolt connection must be deployed between two or more surfaces.

• For automatic bolt connection one must follow these steps, Create COG for the hole à COG is basically a 3D point, convert this 3D point to bolt à Now open connections manager and select the bolt symbol which has created in earlier step à Then assign P1,P2,P3 à Select FE type as Bolt and give the required values and constraints à apply and then realize the connection.
• I have simply given bolt connections by connecting two cluster RB2’s with two node RB2

Spot weld is generally a solid connection deployed between 2 surfaces.

For generating spot weld connection first create a COG point on the FE.

Now, convert this 3D COG point into spot weld using convert option.

Then select the generated spot weld point using connections manager. In the connection’s manager assign P1 and P2 for 2 mid surfaces which are to be connected using spot weld.

Create COG à Convert COG to spot welding point à Use connections manager to generate RBE3-HEXA-RBE3.

After completing surface mesh, volume mesh, mid surfacing and connections we have to use transform option in order to create exact mirror of the model on the other side.

Use transform and select all the entities including connections to generate exact replica of the model on the other side.

Now, use symmetry à mirror 3 points plane option and select 3 points on the edge. These 3 points represent all the 3 coordinates (x, y, z). This helps all the entities to transform on the other side.

Conclusion:

In this project, I have generated mid surfaces and volume mesh using different options available in ANSA. Did topological clean up. Able to achieve better mesh flow using smooth,reconstruct,swap,paste,move options. Eliminated kinks and raised edges. Successfully applied different quality criterias and mesh parameters for different parts and cleared off elements during mesh generation. Successfully deployed connections for the rear suspension. Overall I have done pre processing for rear suspension using ANSA.