Week 12:Project-1-Meshing of Door Inner Panel Challenge

Project-1 Meshing of Door Inner Panel

Aim :- To mesh the given plastic component of door inner panel within given quality criteria and assigning thickness to it.

Given quality criteria :-

Target Element Length = 4 Units

S.N	Quality Criteria	Value
1	Aspect Ratio	5
2	Skewness	45
3	Warping	15
4	Taper	0.5
5	Min. Length	2 Units
6	Max. Length	6 Units
7	Min angle Quad	45
8	Max angle Quad	135
9	Min angle Tria	20
10	Max angle Tria	120
10	Tria %	10

Software used :- Altair hyperworks student version 2020

Theory :-

The door panel covers internal parts like the door handle, window switch, the power window motor, wiring, cup holder, audio speakers, storage compartment and other features. Mostly cars have door panels made from plastic most often using injection moulding, as well as incorporating other decorative materials. The door panel typically incorporates other parts that contribute to the appearance, functionality, and ergonomics of the vehicle. In most cases, the door panel is attached to the car's door frame by visible screws and ones hidden behind decorative plugs or under the armrest, as well as spring clips.

Methodology :-

• Importing Model to hyperworks and geometry cleanup
• Extract mid-surface
• Defeature and proper connection of midle surface.
• Assignning quality parameters
• Meshing part by part, improving mesh pattern and eliminating off elements.
• Assigning property, material card and thickness.
• Performing necessary checks for meshing

Procedure :-

• Import given model by import model command as shown in image below.

• Once model is imported change the visualization to TOPO mode for geometry clean-up.

• There is one big surface missing in model as shown in image below.

• As one side of the surface is missing we can can easily offset from other surface so ther is no need to correct this geometry.
• We can see given model is too complicated so for simplification purpose divide the model in 4 componenets as shown in figure below by using trim with surface option

• Create 4 components and move the all 4 components by using Tools > Organize > collectors option.

• Visible only section 1 for extracting mid-surface and offset outer surface which contains less complicated surface like ribs, cylinder, dog house, etc.
• First we need to measure the thickness of surface by creating one point and projecting same point on another surface and then switch on wireframe mode and measure the distance between two points by pressing F4 key as shown in image below.

• Distance between two points is 2.80mm so we have to offset its outer surface to 1.40mm inside to get mid surface as shown in below image.

• After generating mid-surface captured all the features that are present on another side of surface.
• For capturing rib surface first remove all the fillets by using Defeature > Surface fillet > Select surface > Find > Remove option

• For capturing rib like surface create line between two edges of rib and trim this line to mid-surface as shown in below images and generate new surface by using Surface > Ruled option follow this same procedure to all ribs.

• The features like cylindrical shape or dog houses are captured by surfaces forming plus sign as shown in below images.

• Final view of mid-surface extracted is shown in image below.

• After that, assign quality parameters in Toolbar > preference > Criteria file setting > assign given quality parameters value > apply > OK. As shown in image below.

Quality parameters :-

1. Warp angle :- It is angle between normal of two planes of quad element by spliting it diagonally. The ideal value of wrap angle is 0 degree but it is allowable till 15 degree.

Fig. 1 Warp angle

1. Aspect ratio : It is defined as maximum edge length of element to the minimum edge length of element. Ideal value is 1 but it is acceptable till 5

Fig 2 Aspect ratio

1. Skewness : Skew for quad element = 90 ° – minimum angle between two lines joining opposite mid mid sides of element. (α )

Skew for tria element = 90° - minimum angle between two lines from each node to opposing mid-side and between two adjucent mid-side at each node of elements. Ideal value is 0° and acceptable till 45°

Fig. 3 Skewness

1. Jacobian :- It is scale factor which arises due to transformation of co-ordinate system. Ideal value is 1 but it is acceptable greater than 0.6

• Select component by component and do meshing all over the parts Mesh the surface part by part by using 2D > Automesh > select surface > select mesh size 4 mm > mesh option as shown in image below

• Mesh flow improvement and eliminating quality fail elements. :- After meshing need to check elements which are violating thresholds, for that go to 2D > Quality index option it will highlight the elements which are not as per assigned quality criteria. For eleminating these elements need to use 2D > Quality index > Cleaning tool option in that we can use smooth, element optimization, node optimization, place node, drag tria element, combine tria element, etc options as shown in image below.

• For better mesh flow pattern following practices need to followed :

1.Tria should not face to each other as shown in below image also back to back tria element should be avoided.

Fig.1 Back to back tria should be avoided

2. On a plane surface tria should be avoided

Fig.2 On plane surface tria should avoided

3. Avoid tria at outer perimeter and near to holes.

Fig.3 Tria should not present on perimeter and holes

4. Nodes should lie on surface no kinks,raise or deep present in model.
5. Avoid zig-zag mesh flow pattern
6. No rotating mesh flow patteren present near holes.
7. Holes should be even number of nodes and its edge should be parallel to nearest parameter.
8. Divide the surface in smaller parts by cut option and after meshing remove it by join option for better mesh flow pattern.
9. Defeature the area where quality parameters fails.

• Assign the properties and respective thickness to elements as shown in image below.

• After that check mesh as shown in following points :-

1. Check edges :- By using Tools > edges > Find edges it will highlight the edged. check manually are edges should be on perimeter.
2. Check elements to surface :- For checking elements are captured geometry properly or not this option is used for using this check use Toolbar > Mesh > Check > Elements > comparison > Select element > Select surface > run option as shown in below image. It will shows colored element, red elements means elements are not captured geometry properly, yellow means fine, pink means fine and blue means element captured geometry properly.

3. Check elements normal :- In this check we check the direction of elemements because during simulation if any external force apply it should simulate in proper direction if normal of element is wrong it will not give proper results so this check is very much important. For using this check go to Tools > Normals > Display it will shows elements in green color of red color as per its orientation as shown in below image. If it is different in color according to its orientation then need to change its direction by selecting that elements and clicking on reverse option.

4. Check duplicates :- This checks the duplicate element generated during meshing for using this option go to tools > Check elemenet > Duplicates option it will highlight number of duplicate elements at status bar if duplicates element found click on save failed and go to delete option click on elements select retrive and delete elements.

Final View of model :-

Result :- Thus, the door panel model is meshed properly with better mesh flow pattern and as per given quality criteria and model is ready for further solving and post-processing.