Performed Mixed Meshing of Rear Suspension Assembly in 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.

Model Given:

Procedure:

Quality Criteria for Tria Elements (Tyre and Rim):

S.No	Quality Criteria	Value
1	Target/Average length	7.5
2	Minimum Length	5
3	Maximum Length	10
4	Skewness	45

Quality criteria for Tria Elements (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:

S.No	Quality Criteria	Value
1	Tet-collapse	0.2

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

Perform topo so that some geometrical errors can be fixed. Then perform geometry cleanup

and fix the issue automatically and manually

After geometry clean up performed surface mesh:

The Spot Mesh algorithm gives better results than the free meshing method and creates the optimum number of shell elements, taking into account the element type already selected and the defined meshing parameters.

Select the proper element type, using the Mixed, or Quad, or Tria (Ortho Tria)option.
At all types and methods of ANSA meshing, the element nodes lie precisely on the CAD-surface.

Tyre

Rim

Support arm, Calliper, Disc Brake

Define volume: This function automatically defines multiple volumes using already meshed macros or FE-model mesh.

Activate the Define function.

1. Two modes are available (one at a time) for the definition of the closed volume, according to the flag that is activated in the MODE window that appears on the screen.

2. If the AUTO flag is active then, by selecting a Macro Area, an automatic search is performed and all neighboring Macro Areas that may compose a closed volume become highlighted. Deselect any of the highlighted Macro Areas with the left mouse button, if they
should not participate in the closed volume.

3. If the MANUAL flag is active, the user can select or deselect the Macro Areas or FE-Model shells that will compose the closed
volume.

Then perform 3D Mesh using the below option:

1. Tetra Rapid: The Tetra Rapid algorithm meshes the Volume with Tetra Elements.
The maximum growth rate, which is the approximate growth factor of volume element size from layer to layer while the generation moves towards the interior of the Volume.

- Maximum Element Length. Specify the maximum allowable length of the tetra elements to be generated. Useful when specifying a growth rate factor while keeping the length of the elements below a certain value.

2. Tetra FEM: This function automatically creates a Tetrahedral mesh inside selected Volumes, initially with pyramid elements if the starting surface mesh contains quad elements. It is to be used mainly for structural applications. Volumes to be meshed with this function must have been defined using the Define(Volumes) function.

Volume Mesh Tyre

Volume mesh Rim

Brake Calliper & Support arm volume mesh

Masked View Tyre and Rim

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2D-Meshing of a Lower Control Arm

Errors can be rectified and corrected by the use of auto fix present in check-up bar and also
manually it can be done.

Extract mid surface of inner and outer Hood panel
In order to extract mid surface first, we need to lock down the surface where we have to work
After locking down the view, check for the thickness everywhere so the mid surface can easily be
extracted
The mid surface is extracted by mid surface command present.

Mesh the model according to the given quality criteria.

2D Mesh - lower arm support

Modeling of Coil Spring using CBAR.

CBAR: Defines a simple beam element (CBAR) between two selected grid points, 3D-points

etc. By default, such elements are represented in ANSA as a thick blue line connecting two

blue crosses.

Operations :

1. Activate the CBAR function.
2. Select according to the Pick mode: Nodes, Curve (seq.), Curve (box), Node sets, Edges.
3. Next, the CBAR NASTRAN card appears, for the first selected set of points. The fields that could be automatically filled have been already set.
4. Edit the fields accordingly. At the end of all input press ENTER or the OK button.

5. The new simple CBAR element is defined and it is visible as a blue line connecting two blue crosses. If the \'Element Orientation\' flag of the Presentation Parameters window (F11) is active, then the coordinate system of the CBAR is visible in yellow color.

Coil Spring with the assembly

At last necessary connections have to do on the model:

Connections:

Procedure :

1. Feature Line to Curve) defines 3D-curves from the selected feature lines (elements\' edges) of mesh.

2. Free boundaries of the visible mesh-area are considered as feature lines. Properly defined 3D Curves can be used to generate new geometry from a FE Model.

3. a. Activate the Convert [3D points] function.

b. Select one or more 3D-points (cyan squares) or circle centers (cyan circles). Deselect any of the selected entities, using the right mouse button, if necessary.

c. Confirm the selection pressing the middle mouse button. In the Connection Type window that appears to select the appropriate connection type

4. a. Activate the Connection Manager function, of the Assembly toolbar.

b.Select one or more Connection entities using the \'Connection Selection Assistant\' or the mouse. The selected Connections are highlighted.

c. Load the selected Connections to the Connection Entity List by confirming the selection with the middle mouse button.

T Joint-shell-closed-connection

SpotWeld connection

Cluster RBE2

Bolt connections using RBE2

Full Assembly

Isometric View of a Suspension Assembly

After all the meshing and connections have done, performed symmetry on the model to have a complete picture of the suspension.

Transform [COPY]: This function is used to Translate, Rotate, Transform, Scale, Symmetry

or Mirror selected entities (Faces, Points, Elements, etc). The selected entities are copied in

the new position.

Top View of a complete suspension model

Conclusion

• Got the complete exposure of the pre-processing steps that can be performed in ANSA which includes Importing model, Geometry cleanup, Mid-Surface Extraction, Element Cleanup, Assigning PIDs. Surface meshing for 3-D meshing, Penetration & Intersections errors, Volumemesh, Connections, Transformation.

• Exposure to handle assembly in ANSA