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

AIM:To mesh the given side door inner panel by following the given quality criteria and assign thickness to the meshed model.

OBJECTIVE:

• Creating midsurface manually of the given plastic model and doing geometry cleanup.
• mesh and learn quality checks and correcting failed elements by different methods
• assign thickness to the complex plastic component.

THEORY:
Door panels serve as an interface between the interior of the car and the inner workings of the door, and between vehicle occupants and the door.
They are expected to meet a variety of design specifications regarding safety, aesthetics, and functionality. In addition, they are expected to continue the material theme of the dashboard and pillars while concealing intricate electrical and mechanical components for operating locks, windows, and other features.
The door panel has evolved from a simple two-part system of latch and simple winding mechanism to a more sophisticated enclosure.
Doors currently have an inner full-width panel consisting of electronic windows, central locking system, and speakers. These panels typically consist of a foamed core covered with either textiles or plastics.
Door panels were formerly made of cardboard with an upholstered interior finish of vinyl, leather, cloth, carpet or other materials for the decorative trim. Modern cars typically have door cards made of plastic, most often using injection moulding as well as incorporating other decorative materials.
The design should incorporate both the necessary service amount and the functional unit. The door panel typically incorporates other parts that contribute to the appearance, functionality, and ergonomics of the vehicle. These include armrests, switches or other controls for windows and the locking mechanism, convenience lights, audio speakers, storage compartments, and other features.

original CAD image :

Criteria:

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

Procedure:

1. Import the model :

Import the given model into HyperWorks using the option File → Import → Import geometry → Choose the file → Import.

2. geometry clean up:

The given component is a plastic component so it has different thickness and many ribs so we need to perform geometry clean up to extract mid-surface more accurately.⦁ Once the model is imported, we check it in wireframe mode in 'By Topo' view to check for free edges. As this model is complex and not fully closed, the automatic midsurface may not work properly. So, we need to extract it manually. the geometry can be corrected using tools in quick edit, ruled, spline etc

defeature few fillets in the model that donot satisfy the min element size so the we wont get min size error at the end and also to extract mid surface of the ribs more accurately.

3.Mid-surface generation

Since, the given model is plastic and have complex structures, the auto-midsurface may not work properly as expected. So, we need to manually extract the midsurface. One method is to extract the whole surface by using offset method in 'surface edit' panel. In other way, we can use both auto-midsurface and offset tool. The midsurface of parts which are not created by auto-midsurface tool can be produced by using offset tool in surface edit.

The midsurface of base (main part) can be created by using 'sweep' option in auto-midsurface. All other parts can be created by using offset tool. Some of the ribs can be created by using other auto-midsurfacing option

after extracting midsurface there might be some missing surface and other defects which can be corrected through using tools in quick edit.

Incase of ribs , ribs needs to be extracted seperately through offset. Geom. → surface edit → offset . Measure the thickness of each rib, select one side of the rib and create duplicate in the midsurface and offset to a distance half that of the thickness of the rib.

Similarly extract midsurface of every rib. the extracted ribs wont be connected to the midsurface of the base. The offset surface should connected with base midsurface with proper connection. We can use replace edge, node replace, toggle edge tools for making connection with the midsurface.\

We can capture the symmetrical component's midsurface using final edit tool.
Geom. → Midsurface → Final edit tools → Select opposite surface 1 and 2 (Those surfaces in-between the midsurface is needed) → Extract

5. Meshing :

⦁ Once the midsurface is extracted, we can start the meshing as per quality criteria given. So initially we need to save the quality criteria and parameter file as per requirement.
Preferences → criteria file settings and parameter file settings

⦁ While saving the parameter file, save the parameter file bu unticking the geometry cleanup. The automatic geometry cleanup may distort the midsurface. That is why we have done it manually

for meshing we using batchmeshing option in automesh, which will create mesh with lower number of elements not satisfying the criteria.

fot batch meshing go to 2D menu -> automesh -> batchmesh -> select the parameter and criteria file saved earlier -> select the surface and click on extract

• Check the mesh created and use 'rebuild' tool at required region. Correct the mesh flow. Try to avoid back-to-back tria, tria touching each other, rotating quads and trias at free edge. Use rebuild, element edit, replace, drag tria tools for that purpose.

6. Mesh quality check:

For this we use the option 2D → qualityindex as well as Tool → check elems or click on f9 for shortcut. There might be deviations in some or all of the quality criteria which we need to correct by using the various options available in the cleanup tool options available in the qualityindex. Also we can use element edit, replace node options as well for correcting failing elements.

we can also use tools like element cleanup, edit element, rebuild mesh, smooth etc to correct the mesh.

7. edges check :

Check for edges: The components are checked for edges.
Tools → edges → select element dispalyed → find edges,
If no error noticed, delete edges. select element again → preview equivalent → return

8. Normals check :

Check for Normal: The normal direction is checked by following the below steps,
Tools → Normals → display → we can choose colordisplay or vector display.
The defected element's normals are reversed using the same tool by selecting the element.

9. Element to surface check: To check how the element is captured the surface geometry.
mesh → check → elements → comparison → click on element tab shown in source entity → Select element displayed → Proceeds → click surface tab in the target entity → select surface displayed → Tolerance = 0.2 → Run

10. Assigning thickness :

• Thickness checking: View the parent model and check the thickness in every region and then assign a thickness by creating a collector component and organize the mesh into it. The distance tool is used for measuring thickness. For variable thickness areas, Assign the thickness taking an average value of the cross-section.
• Create a new component tab for various region having different thickness and rename them with adding thickness value.
  Right click on browser → Create → Component.
  
• Assigning property: First, we need to create property tab. Right click on browser → Create → Property.
  After creating a property rename and add thickness value to it.
  
• Then for assigning this property to each component, follow this step; Right click on component tab → Assign → select the property tab we created according to the thickness → ok.
• Now Switch to the 2D Detailed Element Representation to check whether the thickness was applied to every region or not.

Quality check :

Final model image:

RESULT:
The given side door model has been meshed as per the given quality criteria and the thickness is assigned. The meshing results only 1.8% trias.

CONCLUSION:
This project helps us to learn meshing on complex structures and how the midsurface is extracted manually for such geometries. It also allows us to work with different tools in hypermesh for extracting midsurface, quality correction, meshing etc.