Shell meshing on the car switch panel using ANSA Preprocessor

Aim:

Obtain a 2D shell mesh from the switch panel and a sheet metal component while following the given criteria.

Target/ Average length	4
Minimum length	2
Maximum Length	6
Aspect ratio	3
Warpage	15
Skewness	45
Jacobian	0.7
Minimum Quad angle	45
Maximum Quad angle	135
Minimum tria angle	30
Maximum tria angle	120
Tria percentage	15

Objective:

• Clear the geometry errors of the parent model.
• Extract the mid surface from the parent model.
• Generate the shell mesh from the mid surfaces according to the given criteria.

Procedure:

Switch panel:

• The switch panel model is opened in the ANSA workspace.

• The surfaces are checked for topology errors and needed action is taken to resolve the errors.

• The component is observed to have various thicknesses at a different position.

• The Auto-mid surface is found to be improper. Therefore, the manual mid surface is extracted.
• The surfaces of the parent component are offset with the appropriate offset distance and appropriate connection between the adjacent surfaces.

• The mid surface of features like locators, stiffener ribs, etc., are approximated since the thickness varies over those small regions.

• The offset surfaces of the switch panel are assigned with the respective thickness values. Separate P’Ids are created and assigned.

• The perimeters of the mid surface component are edited with the element target length of 4mm.
• The quality criteria and mesh parameters are inserted.
• Critical surfaces are meshed first. Best mesh algorithm is used and the mesh is reconstructed again.
• The mesh generation proceeds from the critical areas to the adjacent areas.
• The mesh is reconstructed and manipulated to pass the quality criteria and obtain better mesh flow.
• The meshes from features are edited and some approximations to the features are taken and the nodes of the critical elements are manipulated (by moving the nodes) within the parent model space to clear the quality conditions. Doing so will deviate the mesh from the mid surface, but the node will be still in the parent plastic component. This compromise is taken since it is a plastic component having a mixed thickness at these regions.

• Only 2 elements are allowed to fail the criteria. Out of 2962 elements, 95.72% are quads and 7.73% are trias.

• Time took: 9 Hours.

Sheet metal component:

• The .IGS format file is imported into the ANSA workspace.

• The surfaces are refined for a clear understanding of the surfaces.

• The appropriate connection between the surfaces is created by doing the topo operations. Orientation is changed.

• The mid surface is created by offsetting the surface and surface selection is made by enabling the feature option.

• The mid surface is checked for topo errors and needed action is taken. Some surfaces having errors are deleted and created again selecting the appropriate option.

• The Quality criteria and mesh parameters are inserted.
• Perimeters are edited for the target element length.
• The surfaces are divided and mesh is generated using the best mesh algorithm. Mesh is reconstructed again to obtain better mesh.
• As symmetry is observed in the model, the mid surface component is divided by plane cut and double surfaces are deleted. (The top portion of the component is easy to mesh even with both side surfaces, so only bottom is deleted and meshed for only symmetric surfaces.)

• The symmetry surfaces are meshed. The mirror is created and the appropriate connection is established between the mirrored components.

• A property of 2mm thickness is applied to the mid surface.

• Time took: 5 Hours