Project-1 [Side Door Panel] Hypermesh

OBJECTIVE

To perform 2D shell mesh on the the Side Door panel of car by following below quality criteria:

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

MODEL

FIG:1 

FIG:2

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.

 

METHODOLOGY

 i. Open the file in Hypermesh from the file source folder in the system 

 ii. After importing the model perfrom Topology repair on the model. It consist of correcting connectivity error between adjacent surfaces. Possible errors include :

• Unconnected adjacent surfaces
• Duplicate surfaces
• Missing surfaces

  The goal of topology repair is to restore the surface data to a perfectly clean representation of the parts.

 iii. In this given model some areas are having missing surfaces, it is sloved by Geom-> Quick edit-> Filler surface . If the surface is having deformations can be solved by using Quick edit option which is located in Geom option. In quick edit option use the commands Replace the points and Toggle option used to remove this deformations.

FIG:3 [Quick edit panel]

 iv. In the given model free edge is denoted as Red colour, in this it is associated with only 1 surface. For shared edge it is denoted by Green colour, here it is associated with 2 surface and for T junction edges is denoted by yellow colour. In here it is associated with 3 or more surfaces.

 v. After solving all the Topology cleanup on the parent surface go with extracting the Mid Surface of the model, so a better Mid surface will be getting. By this we can save time working on the Mid surface. Eventhough if we worked on the parent body there will be some small cleanup need to be done on the Mid surface.

 vi. Here i opted with manual mid surfacing of the model in order to get a good Mid surface. To extract the Mid surface go with Geom-> Offset-> Change continuos offset-> Select the surface-> Input the offset value-> Offset

 vii. In the above command series before offsetting select the colour normal first and check whether it comes as blue or red, if it comes as red select Reverse normal so the red colour changes into blue colour. Then offset can used for each surface. By looking the below figures we can understand how manual offsetting is worked on the surfaces.

FIG:4 [ Offset command panel]

FIG:5 [ Surface selected]

FIG:6 [ Duplicating the surface before ofsetting]

FIG:7 [ Normal vector direction from the selected surface]

FIG:8 [ Mid surface]

 viii. The above figures denotes how the mid surface is performed on each surfaces. This are the steps followed to obtain mid surface of each surfaces. The main body is having a thickness value of 2.8mm so offsetted with the value of 1.4mm

 ix.  In the main body surface the surface is selected from outside of the panel inorder to capture surface in a better way.

FIG:9 

 x. After getting the Mid surface of the main body , next step is to defeature the Ribs and to capture the Mid surface of the Ribs 

 xi. Defeature of ribs is done by using defature command which is located in Geom-> Defeature-> Surface fillets. In this option input the minimum radius and maximum radius value. Inputed value of min and max radius is 0.1 and 8mm.

 xii. Below figures shows how the Defeature command will work :

FIG:10 [Surface selected for Defeaturing]

FIG:11 [Defeature command panel]

xiii. After selecting the surface click FIND

FIG:12 [Surface selected with the input values]

FIG:13 [Surface defatured]

 xiv: In some cases surface fillets will not get removed directly. If it comes like that in the surface fillet panel there is a option called "ignore edge assosciated" and "fillet ends". Using this options surface fillets can be removed easily. Below figures indicates how this option is working out the fillet areas.

FIG:14 [ Some areas will come like this]

FIG:15 [Fillet ends are selected denoted with white lines]

FIG:16 [By clicking Remove fillets get defeatured]

 xv: After defeaturing all the ribs extract the mid surface of the ribs. Mid surface of fillets can be obtained by normal offsetting  and other option in the Mid surface that is "Final edit tools".

 xvi: Normal offset method is explained above with figures. Final edit tool is present in Mid surface command.

   

FIG:17 [Above figures indicates how to open Final edit tools to extract the mid surface]

 xvii: In the above option, select 2 surface of Rib and click extract button to obtain the mid surface.

   

FIG:18 [Defeatured RIB]

 

FIG:19 [2 Surface selected]

FIG:20 [Mid Surface of Rib]

 xviii. After extracting all the Ribs in the parent body, extend all the ribs to Mid surface. It is done using Extend command , shortcut key is Shift+F9. Main use of the Extend subpanel to extend or retract the edges of selected surfaces to meet other selected surfaces, or to close gaps between surfaces or holes within a selected surface. In the extend command surface that need to be extend should select first and select the surface that extended surface to join.

FIG:21 [Mid surface of Rib is generated]

FIG:22 [Arrow marks indicates the surface that need to extended]

FIG:23 [Lines to extend over]

FIG:24 [Surface to target]

FIG:25 [Surface extended]

 xix: Similarly for all the ribs this processes need to be continued. In some areas the extended surface will make the Mid surface get to be deformed. If it happens the surface need to reworked then only rib will attach to surface exactly

 xx. After completing all the above processes Mid surface of the side door panel is generated.

  

 

FIG:26 [Mid Surface of side door panel]

 xxi: Next main step is to generate 2D mesh elements on the Mid surface.

 xxii: During meshing somes things need to care about:

1. The tria elements should never be opposite each other.
2. No tria elements should be connected back to back.
3. No tria elements should be in the edge of the geometry.
4. No tria elements should be near the hole
5. No tria elements should be on the feature and fillet areas.
6. There should be less tria concentration      

 xxiii. This steps allowed to have good mesh for analysis in the slover deck inorder to get better results.

xxiv. Before starting to do the meshing input the quality criteria values 

FIG:27 [Quality criteria values]

xxv. Before start with the meshing some details of quality criterias:

1. Warp angle (Warpage): It is not applicable for triangular elements. It is a way to measure how far is a Quad element being planar
2. Aspect Ratio : Maximum element edge length / Minimum element edge length
3. Skewness ( Ideal value = 45 degree) : Skew for quad= 90 deg - Min angle between 2 lines joining opposite mid side and Skew for Tria element= 90 deg - Min angle between the lines from each node to the opposing mid side and between 2 adjacent mid sides at each node of the element.   

xxvi. Meshing is carry out inorder to have finite element method to reduce Degree of freedom from infinite to finite with the help of discretization 

xxvii. Mesh can be generated by 2D-> Automesh-> Select the surface-> Mesh

 

FIG:28 [Automesh panel]

FIG: 29 

xxviii. As the meshing is completed look for quality issues in the quality index, 2D-> Quality Index

xxix. In quality index it consist of all the cleanup tools for clearing the quality issues in meshing

FIG:30 [Cleanup tools]

xxx. Tool details:

  a. Place node tool: Choose which direction to node move

FIG:31

  b. Swap edge tool: Use the Swap Edge tool to consider the elements to which the edge belongs, and find alternative orientations for it. Each time you click an edge, it switches to the next valid configuration. If an edge swap will not improve element quality, a message to that effect displays in the status bar. To force the swap anyways, click the edge a second time. Additional clicks will cycle through the possible edge positions. The number of possible edge positions depends on the types of elements involved.

FIG:32

  c. Node optimize tool: se the Node Optimize tool to automatically move a selected node to optimize the overall quality of its surrounding elements. The options along surface, normal to surface, and along and normal to surface work exactly as described for the place node tool. The only difference is that node optimize moves the node automatically, while place node requires you to choose the location manually.

FIG:33

  d. Element optimize tool: Use the Element Optimize tool to automatically optimize the shape of the selected element and the elements surrounding it. It is similar to Node Optimize, except that its effects are wider-spread.

FIG:34

  e. Smooth tool: Use the Smooth cleanup tool to improve element quality in a surface-based mesh. This cleanup tool uses one or more algorithms to adjust node positions to moderate sharp variations in size or quality in adjacent elements, and to adjust the position of the free nodes of the selected shell elements to smooth out variations in element quality and size.

  f. Split/Collapse edge tool: Use the split/collapse edge cleanup tool to split or collapse the edges of elements in your model.

FIG:35

  g. Drag Tria elements: Use the drag tria element cleanup tool to drag a tria element to a different location in the model, or out of the model completely. To use the drag tria element cleanup tool, left-click on a tria element and drag it to a desired location. HyperMesh highlights the selected tria element in pink.

FIG:35

  h. Split Quad element tool: Use the split quad element cleanup tool to split a quad element into two tria elements.

FIG:36

  i. Combine Tria elements tool: Use the combine tria elements cleanup tool to combine two tria elements into one quad element.

FIG:37

xxxi. In this model all this tools are used at a time inorder to achieve a good mesh flow. For converging areas in the model, trias can allowed to come 

xxxii. ISome of the areas will have Warpage issues. Inorder to clear this issue try with the Translate command. 2D-> Translate select the nodes which is going downwards in comparison with other nodes. And select the plane N1 and N2 and give tolerance value to be 0.01 , 0.02 as minimal value and 0.05 , 1 for large . By doing this command warpage can be cleared, here it is trying to distribute the  angle values to the adjacent quads and trias.

xxxiii. Using Translation and Cleanup tools will clear the Quality issues in the whole model.

FIG: 38 [Full mesh generated on the Mid surface of Side door panel]

xxxiv. After generating the mesh on the whole model, give connection on Clipping hole and Main mid surface body. In this model RBE3 connection is generated inorder to give Rigid connection

FIG:39 [ RBE3 CONNECTION]

xxxv. The last step is to assign thickness to each part of the model. To assign the thickness first create a components in the tree structure and organise all the elements to their respective components.

FIG:40 [Components created]

xxxvi. After creating the components create seperate property for each components. In the Property tab itself input the corresponding thickness value. 

FIG:41 [Thickness assigned in the Property]

xxxvii. Next step is to assign the respective property to each components

FIG:42 [Property assigned to each component]

xxxviii. Last step is to setup the Normals for the surface, for that Normals command is present in tool panel. 

FIG:43 [When checking the normals]

xxxix. After this all the blue region need to changed to Red area. So select the elements and display the normal colour and just reverse the colour to Blue.

FIG:44 [Select the elements]

FIG:45 [ Display the elements]

FIG:46 [Reverse the display elements to Blue]

RESULT

2D mesh is generated on the Side Door panel of the car

FIG: 43 [Panel with mesh generated with respective thickness assigned]