Pre-processing of a switch panel

TOOL TEST -1

OBJECTIVE:
The objective of this tool test is to perform a mid surface extraction of the component and successfully create a finite element model of it and furthermore refining the mesh such that it validates every quality criteria set.

Tool tests are usually required to be completed within a given period. Hence timing the duration to complete each component respectively is recommended.

PROCEDURE:

1. Geometry Cleanup

Initially, every model has to be checked for geometrical errors. Prior to this, it is best practice to perform a topology clear up to make sure that continuity is maintained between every cons and that it doesn't display double cons as single cons.

ANSA can give a layout of all the geometrical error from our component model.

To perform geometric checks, Checks - Geometry - Select required params

ANSA is also capable of clearing small geometrical errors if it's within its capability and based on memory allocated for it.

In both the components, ANSA was able to clear all geometrical errors

2. Mid surface extraction

Mid surface extraction depends on the symmetry and thickness of each respective part in a component. In case of varying thickness, the auto mid surface doesn't give a proper result. Hence manual mid surface extraction using the offset and manual mid features can be implemented.

The offset command can be used for known thickness features in the component where discontinuity occurs due to other mid features present. Whereas the single/multi middle feature can be used for features that are symmetric and are separate from the rest of the component (i.e no discontinuity)

• Strips along the surface can be extracted for mid using the offset feature post to measuring the thickness of the strip by projecting any node onto the opposite con
• Small rib features around the cylindrical part can be extracted using the single middle feature
• Deformed or out of boundary edges can be recreated using the faces cut feature
• After manual mid extraction the component may be discontinuous this can be rectified using the Extend and trim feature provided by ANSA pre-processor
• To extract mid of cylindrical parts, the thickness can be measure either by projecting the Hotpoint onto the opposite con or if that is not possible then the weld spot feature can be implemented to determine the thickness and then extracted using the offset command (thickness/2). Finally, the surrounding ribs can be connected to it using the extend command

Mid-surface of component-2 (Switch Panel)

In the case of 2nd component,

Since the model had a uniform thickness over its length, taking auto mid surface is less time and the necessary mesh parameters are respected over the entire model. The auto mid feature gave a more appropriate result fairly quickly

The end model result is shown below,

4. Mesh generation and Refinement

Finally, the part has to be meshed to complete the pre-processing stages.

Prior to meshing, the mesh parameters and mesh quality criteria has to be set.

The quality criteria that every element in the mesh has to satisfy is shown below,

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
10	Tria Percentage	15

To generate mesh, in both cases the Best method was chosen.

To refine the mesh, commands like reconstruct, reshape, smooth etc are used to perform certain operations on the mesh thereby minimizing the no of elements that fail the quality criteria, to get a smooth mesh flow with relatively more quads.

The mesh was refined and the best possible mesh was given to the FE model as shown below,

CONCLUSION

1. The time took to complete model 1 was about 2hr 43min because of intricate features in the component and manual mid surface extraction

2. The time took to complete model 2 was about 27mins because of auto mid extraction