Project - 2 - Meshing on the suspension Assembly

MESHING AND DEPLOYING CONNECTIONS FOR REAR SUSPENSION ASSEMBLY USING ANSA

AIM:-

1) To check for the geometrical errors and clean the geometry for the given assembly.

2) To Perform surface and Volume mesh ( tetra mesh ) throughout the assembly.

3) To assign thickness for the mid-surfaced components after meshing.

4) To Finally provide connections wherever required throughout the assembly.

PROCEDURE:-

1)Importing the CAD model:-

1. First,we import the CAD model of the Rear suspension assembly into the ANSA database using the Open option present in the File tab.

2.Then we go to the Mesh module and click on length option under the Perimeters tab to give the Perimeters and macros length,initially it is given as 1 for better visualization of the CAD model as shown in the images given below.

    Fig 1,2-we set the Perimeters and Macros of the CAD model to 1mm for better visualization.

3.we then perform the TOPO operation on the whole model which is present under Faces in the Topo module and proceed to clean the geometry because there are errors like the unchecked Faces present in the CAD geometry.

2) Geometry Cleanup:-

1.Under the Geometry cleanup,we go to the check geometry option under the Tools tab.

2.we run the geometry check and after that we find there are  errors present in the geometry such as Crack Between cons, unchecked Faces. The check geometry manager results are shown in the image given below.

                                  Fig 3.Geometry errors present in the model.

3.we then clear all the errors manually to get a good geometry of the CAD model and again run the Geometry check,Therefore we get a CAD geometry with no errors on it as shown in the image given below.

                  Fig 4. After clearing all the Geometry errors in the model.

3) Mid-surfacing:-

      1) we,first measure the components that are required for creating the mid-surface using the Measure option present under the Utilities tab.

      2) Then,we start taking mid-surface for following components bracket,circular disc,base plate assembly and the conicalcomponent.

      3) we use the offset option under the Faces tab of the Topo module to take the mid-surface.

               Fig 5.Parts that are taken mid-surface to do 2D meshing using Offset option.

      4) we create Different PIDs for all the mid-surfaced components using SET PID option.

              Fig 6.PIDs set for the mid surface ( PART 1 to PART 8 )

        5) we store a lock view of the mid-surfaced components,so it could accessed easily in the Future.

4) Meshing:-

     1.2D Meshing :-

           1.In the 2D Meshing,we will be considering only the above mid-surfaced parts and we will be meshing it with mixed elements that include both quad and tria elements according to the given Quality criteria.

           2.we use the Best option under the Mesh Generation tab of the Mesh module for generating the mesh over the midsurfaced components.

           3.we clear the quality issues in the mesh to get a good mesh over mid-surface of the component using the Reconstruct option under the Shell Mesh tab and Split,Swap options under the Elements tab of the Mesh module.

           4.we,Finally get to see the completely meshed model of the mid-surfaced components as shown in the image given below.

                              Fig 7.After meshing the mid-surfaced components

   2.3-D Meshing (Volume Meshing ):-

5).In the 3D meshing   ( or ) Volume meshing ( Tetra meshing ) , we will be considering the whole volume of the unmeshed components individually and we will be meshing it with ortho tria and tria elements according to the given quality criteria.

6) We first perform 2D mesh over all components using tria and ortho tria elements according to the given quality criteria.

7) we use the Spot Mesh option under the Mesh Generation tab in the Mesh module to Perform 2-D mesh for all the unmeshed components one by one.

8) Then,we clear the quality issues in the mesh to get a good mesh over mid-surface of the component using the Reconstruct option under the Shell Mesh tab and split,swap options under the Elements tab of the Mesh module.

9)After that,we define the volume for the components using the Define ( Manual ) option under the volumes tab of the volume Mesh module one by one and also create Different PIds for different components as shown in the image given below.

                            Fig 8.PIDs of the Rear suspension assembly

10)we,then perform volume mesh over all the components one by one using the Tetra FEM option under the unstructured Mesh tab of the Volume Mesh module.we also check whether there are tetra collapse elements in all the components one by one.and clear the tetra collapse elements using the Fix Quality option under the Improve tab of the Volume Mesh module.

                         Fig 9.Volume Meshed Components

11) we define the material for all the 2-D and volume Meshed Components as shown in the image given below.

                         Fig 10.Materials defined for the 2-D and volume Meshed Components

12) we also assign thickness to the 2-D meshed components Then,finally we are done meshing all the components .The final meshed assembly of the rear suspension is shown in the image given below.

                            Fig 11.Final Meshed model of rear suspension assembly

5) Connections:-

    After meshing the suspension assembly we proceed to give connections to the model with the following types of connections.

1.RBE2 connections:-

1)RBE2 Single Cluster Connections:-

      In this type of RBE2, we provide connection to two (or ) more holes on two ( or ) more surfaces which are nearer to each other and lock their in all axes and all degree of freedom so that they cant move in any direction which makes them as rigid  during the noise,vibration and harshness simulation in NASTRAN. we should go to NASTRAN module and under Elements tab we select the RBE2 option .we provide these types of connections wherever there are two ( or ) more holes nearer to each other as shown in the image given below.

                                                      Fig 12.RBE2 Single cluster connection

2)RBE2 spider connections:-

     In this type of RBE2,we provide connection to one hole which is present on the model to make it rigid in all the axes which avoids movement of it during the noise,vibration and harshness simulation in NASTRAN. we should go to NASTRAN module and under Elements tab we select the RBE2 option.we provide these types of connections where there are independent holes present as shown in the image given below.

                                                    Fig 13.RBE2 Spider Connection

3)RBE2 Two node connections:-

In this type of RBE2,we provide connection in places like where there are two RBE2 cluster connections in the model.we should go to NASTRAN module and under Elements tab we select the RBE2 option and under RBE2, we select the Two Node option then we select the two required nodes to create a connection as shown in the image given below.

                                                     Fig 14.RBE2 Two Node connection

2) C-Bar connections:-

In C-Bar connection,we provide connection only to the spring in the shock absorber as it translates w.r.t an axis.we try to capture it as a 1-D element instead of meshing it.we first,create a curve of the spring using the Middle option in the curves tab of the TOPO module and then we go to the NASTRAN module and under Elements tab,we select the C-Bar option on selecting it a dialog box opens having options for how the C-bar has to be represented namely nodes,curves(seq),curves(box),node sets and edges we the curves (box) option and then we need to create a new PBar property .On confirming,we get spring which is captured with 1-D elements as shown in the image given below.

                                                 Fig 15. C-Bar Connection

6) Providing Symmetry to the Model:-

      After we finish giving connections,we have to provide symmetry to the model so that the system would look completed For this,we go to the Transform option in the Utilities tab and we select the entities needed to be given symmetry,on confirmation we have to select Mirror Three points plane, then we select three points , so as to get the symmetry.Finally we obtain the Complete Model as shown in the image given below.

                                Fig 16.Complete Meshed model of the rear suspension assembly

Conclusion:-

1) we have checked for the geometrical errors and cleared the geometry for the given assembly.

2) we have Performed surface and volume Mesh ( tetra Mesh ) throughout the assembly with the given element Quality criteria.

3) we have also assigned thickness for the mid-surfaced components after meshing.

4) we have finally also provided connections wherever required throughout the assembly.

Learning outcomes:-

   1) clearing all the geometric errors for complex systems. 

   2) Performing Both 2-D and volume Meshing for Complex systems.

   3) Performing Connections to all the necessary areas of the assembly for Complex systems.

Model Link:-

https://drive.google.com/file/d/1cRvQjq2YKb_8VQ9nMp_qUXbiA-oeAUhJ/view?usp=sharing