Week 12:Project 2-Meshing of Rear Wheel Holder challenge

Project-2 Meshing The spare wheel floor Panel

Aim :- To mesh the given spare wheel floor panel within given quality criteria and assigning thickness to it.

Given quality criteria :-

Target Element Length = 5 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	8 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 :-

Spare floor wheel panel is manufactured by stamping process in which flat sheet metal is forms into a stamping press where tool and die surface forms the metal into a net shape.

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.
• Here, we can see that lot of surfaces gets distorted, missing and doubled need to eliminate these errors manually by using quick edit tool and deleting unnecessary surfaces. Before and after of these geometric errors are shown in below images.

• After fixing all geometric errors manually extract mid surface automatically by using Geometry > Mid-surface > extraction option > offset + planes + sweeps > auto extraction > Select surface > Extract option as shown in image below. It will extracted mid-surface.

• Before proceeding to meshing clean all geometric errors manually of mid surface and auto clean-up the mid surface.

• 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. Warp angle

2. 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. Aspect ratio

3. 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. Skewness

4. 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 surface by surface and do meshing all over the parts Mesh the surface by using 2D > Automesh > select surface > select mesh size 5 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. Back to back tria should be avoided

2. On a plane surface tria should be avoided.

Fig. On plane surface tria should avoided

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

Fig. 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.

• Create new property and material as shown in image below and assign it to the component.

• After meshing check the 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 extra wheel floor 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.