Pre-processing of Suspension and Wheel Assembly using ANSA

Pre-processing of Suspension and Wheel Assembly using ANSA

Objective: 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. Deploy connection between components. Also, write a detailed report explaining procedures.

Quality Criteria: In this model we have been provided with three different criteria for different parts.

Quality Criteria for Tria Elements (Tyre and Rim):

S.No	Quality Criteria	Value
1	Target/Average length	6.5
2	Minimum Length	5
3	Maximum Length	10
4	Skewness	45

Quality criteria for Mixed elements (For Midsurface only):

S.No	Quality Criteria	Value
1	Target/Average length	4
2	Minimum Length	2
3	Maximum Length	6
4	Aspect	3
5	Warpage	15
6	Skewness	45
7	Jacobian	0.7
8	Minimum Quad Angle	45
9	Maximum Quad Angle	135
10	Minimum Tria Angle	30
11	Maximum Tria Angle	120

Quality criteria for Tria (For other components):

S.No	Quality Criteria	Value
1	Target/Average length	4
2	Minimum Length	2
3	Maximum Length	6
4	Skewness	45

Common Quality Criteria for Tetra elements are:

S.No	Quality Criteria	Value
1	Tet-collapse	0.2

Modelling Procedure:

Importing the model: The given model has been provided with .IGS format, we imported it in ANSA. Initial stage of the model is shown as below.

Geomtery Cleanup: In order to minimize errors at later stages we remove any irregularity from model by doing Geometry Cleanup. To do so we went to Checks Manager>Geometry>Run. The errors received after running the check are shown below:

Geometery Errors

However, these errors could be resolved using Auto-Fix. The below image shows all errors resolved.

Errors Resolved

Setting up PIDs: In order to access each feature easily we assigned separate PIDs for them. Below image shows all feature assigned with Shell PIDs:

Meshing Tyre and Rim: Since the tyre and the rim have different quality criteria we meshed it separately. In order to create the tetra we first have to do 2D mesh. In order to do that we fed the given criteria to the ANSA. In order to mesh these parts we used Mesh Generation>Spot Mesh, below images shows the same. For meshing the plane surfaces we used Tria elements however, for curved features we used Ortho Tria. The off elements were corrected using Reconstruction.

Rim and Tyre meshed using Shell Mesh:

Features with varying thickness: For such regions we have been provided with separate quality criteria, thus we have to re-enter quality and mesh parameters. The same has been shown above. For these features we will use similar technique as used for rim and tyre. Below image shows these features with shell mesh.

Now in order to create 3-D mesh we have to first define the volumes. In order to do so we have to go Volume Mesh Deck> Volumes> Define>Manual. However, for few features we need to devide it into few parts and define each part separately, otherwise it may give errors while generating Volume mesh. All the defined volumes in given model are shown below.

Once volume is defined we can generate volume mesh either using TETRA FEM or TETRA RAPID. Tetra FEM is generally used for structura analysis and it is important to define the volume for this, however, TETRA Rapid mesh is used for automatic genartion of Tetrahedral mesh and defining volume separately is not required.

Features with Uniform Thickness: As per the requirement of the project we have to generate mid-surface for the features with uniform thickness. For the given model we created mid-surface for strut and bracket as it had an uniform thickness of 3mm. In order to create mesh for this features we used Faces>Offset. Below image shows mid-surface generated using this method:

For creating mesh on this features, we fed the above given Quality criteria to ANSA and generated mesh using Mesh Generation>Spot Mesh. For this we used mixed elements. Off elemets received were fixed using Reconstruction tool. Below image shows the mesh created.

Representing Spring as 1-D Bar Element: In order to show the spring as 1-D element, we have to first create a curve, which was done using Curves>Middle. Once created we will join all parts of spring as one element using Connect>Multi. Once done we will create a COG point on curve. Once created we need to open NASTRAN Deck>Elements>CBar> Curve Box. After selecting the curve we have to enter the element size radius of the element. Procedure to do so generate is shown below.

Once the 1-D element is created to view the representation as solid we have to change Line Element Cross-section as Solid in Presenation Parameters. Below image shows Spring as the 1-D bar element.

Connections: For the given model we have used seam weld connection, RBE2 Cluster and Two-node RBE2. Using these we have representated connections and locking of componenets on other parts.

Seam Weld: In the given model we have applied seam weld where features are directly attched with another feature's face. We have applied Seam weld on Strut bracker. In order to create Seam weld, we first used CONS2Curve Tool. Then using Convert we converted it into seam line. Now using Connection Manager, we realised the connection for FE REP we used Y-Joint shell. Below image shows the seam weld connection after realising.

Bolts: For representing Bolts connection we have used two RBE2 Cluster on each side and connected them using RBE2 Two-Node. For e.g. on wheel rim we created two RBE2 cluster on rim and one on break assembly and using Two-Node RBE2 we connected the master nodes. Below are the images of the same.

Also, for features having their spilnes or joints connected with hub of other components we represented them as locked using Two-Node RBE2, also as spring is not attched with any other component in model we made a connection using RBE1 cluster. Below are few examples of the same.

Once all required connections are made our model is ready, below is image of complete FE model of the assembly.

Learning Outcome: By working on this model we learnt about modelling of complex assemblies. Leant to work with both Shell and Solid mesh on a single model. Learnt about establishing connection on various componenets. Learnt about 1-D bar element and how to model them.

Conclusion: Hence the model has been completed as per requirement. The mesh for different componenets has been generated with given quality criteria. Mid-surface is generated for features with uniform thickness and meshed with Shell elements, Volume mesh has been done on other components. Also, all required connections have been made.

Link for the model:

https://drive.google.com/file/d/1ajlGGJJyRYqPxv7qYPJD8OdnEKawWejG/view?usp=sharinghttps://drive.google.com/file/d/1ajlGGJJyRYqPxv7qYPJD8OdnEKawWejG/view?usp=sharing