Challenge

Project - 2 - Meshing on the suspension Assembly

AIM :

Importing Rear car suspension geometry into ANSA
Cleanup the Geometry until no topological error is found
Generate mid surface for required parts
Generate volume mesh for hollow parts
Improve the mesh flow and solve off elements according to given quality criteria
Give connection for rear suspension

INTRODUCTION :

Suspension has been an essential component of automobiles. The Rear suspension of a vehicle perform the same general function as front suspension, but specific construction is typically quite different.
The ideal suspension for a vehicle depends a lot on the vehicle's body style and performance requirements. The most basic purposes of a suspension system are to prevent the body of a vehicle from hitting the ground and to keep the tires in contact with the road
Suspension system are generally classified into dependent and independant systems. the wheels in a dependent system are perpendicular to the axle and parallel with each other.
The Most common suspension of this type is leaf spring rear suspension , which consist of multiple metal bars , or leaves , bound together . it is an older design but is still most common on trucks and other heavy vehicles.

QUALITY CRITERIA :

For Tyre & Rim ( Volume mesh - Tria element )

For Other components ( Volume Mesh - Tria element )

For Mid Surface

PROCEDURE :

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

Clean the geometry using checks manager . Enable unchecked faces , collapsed cons , triple cons , needle faces , overlapped faces , cracks , single cons . clear all these issue 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 option 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 meshing 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 meshing option . The 1st 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 the 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 next we proceed further to volume mesh geneation.
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 whole geometry. so, define indiviual closed volumes for different PID's.
Define 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

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 tria are used as surface mesh for volume generated parts.
After surface meshing, define closed volume indiviually 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.

MID SURFACE GENERATION FOR SUB FRAME AND MACPHERSON STRUT OUTER SURFACE

Here i used the Casting option for generating mid surface for sub frame and macpherson struct outer surface
The advantage of using casting is that ANSA generating mesh along with mid surface . Don't forget the given quality criteria for mid surface.

CONNECTION FOR REAR SUSPENSION

After completion of mid surface and volume mesh we must connect them by using connection like bolt connection spot weld connection , seam weld connection etc.
Bolt connection can be generated can be generated using RBE2 option in the NASTRAN deck.
CLUSTER RBE2 : 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 bolt a new open connection manager and select the bolt symbol which has created in earlier step a then assign P1,P2,P3 a select FE type as bolt and give the required values and constraints a apply and then realize the connection.
I have simply given bolt connection by connecting two clusted RBE 2 with two node RBE2 as shown in following image

SEAM WELD : generally a solid connection deployed between 2 surfaces.
For generating spot weld connection first create a FEAT2CURVE on the FE.
Now, Convert this curve into seam weld using convert option.
Then Select generated seam weld point using connection manager . In the connection's manager assign P1 and P2 for two mid surface which are to be connected using seam weld.
Create COG a convert COG to Seam welding point a use connections manager to generate OVERLAP-SHELL

TRANSFORM

After completing surface mesh , volume mesh , Mid surfacing and connection . 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 connection to generate exact replica of the model on the other side.

Now , use symmetry a mirror 3 points plane option and select 3 points on the edge. These 3 point represent all the 3 coordinated (X,Y,Z) this helps all the entities to transform on the other side.

FINAL MODEL IMAGE :

LEARNING OUTCOMES :

Able to do topological clean-up with no errors.
Assigned separate PIDs for different surfaces and volumes.
Able to generate mid surface and volume mesh.
Aware of all the quality criterias and mesh parameters during mesh generation . Learned how to improve mesh flow and remove trias to acheive better mesh flow.
understood all the concepts regarding mid surface generation . Learned how to improve mesh flow and remove trias to acheive better mesh flow.
Understood concepts regarding connection. Deployed different types of connections.
Understood all the concepts regarding mid surface generative , Volume mesh generation , meshing , connection used for NVH analysis in ANSA.

CONCLUSION :

In this project , I have generated mid surfaces and volume mesh using different option available in ANSA .
Did topological clean up . Able to acheive better mesh flow using smooth , Re - construct , Swap , Paste , Move option . Eliminate kinks and raised edges .
Successfully applied different quality criterias and mesh parameters for different parts and cleared for the rear suspension .
Overall I have done pre processing for rear suspension using ANSA.

ANSA file :

https://drive.google.com/file/d/1L0xwoITy2esqGsFiAt20R82P0KcwXYa0/view?usp=sharing

Ship work like this
in your own course.