2D Meshing of the Automotive side door component using Hypermesh workbench.

AIM : Mesh the side door component ( plastic component ) and assign thickness .

OBJECTIVE :

• Clean the geometrical error and fix or remove the deformation in the model.
• Extract the mid surface from the model ( manual mid surface )
• Give the proper quality criteria
• check for the features were minimum length will fail, and make changes according to criteria
• Mesh the component with given element size and remove all the quality errors with proper feature capturing
• Assign the thickness to all the features accordingly.

PROCEDURE :

Step 1: Import the geometry

To import the geometry go into Import option, in import option click on import model, select the model to import and then click on import. (If model is not visible, on keyboard press "F" so that the model will be visible on the screen)

Refer the Figure 1 below.

{ Figure 1 }

Step 2 : Criteria for the given model.

• Check for the given criteria.

• To set the given criteria, Go into Preferences > criteria file setting > Fill the value according to the given criteria as shown in the Figure 2 below.

( Figure 2 )

Step 3 : Inspection of the Model .

• Check the model through out, check for the features check for small component. Inspection is important for a model because there might be some defects or some error while importing the model. Secoundly inpection is done so that one can know which are the complicated parts or features inthe model. By inspecting we can decide where to start from, which area may take a lot time to clean up.
• We can get good view of the component in the topo mode.In topo mode basically we can clearly see the surface, such as we can see the free edge in red, two surfaces connected with each other with a green line and if three surface sare connected to each other yellow line is visible. (Refer Figure 3 and Figure 4 .) ( Figure 3 is the auto view and Figure 4 is topo view )
• To on the topo mode first go to visuallization menu. In visualization menu the view is pre setted on the auto view, just click on the down arrow beside the menu nd change the view to topo view.

Figure 3 Figure 4

Step 4 : Cleaning the parent geometry

• Cleaning of the parent geometry is very important to get a good midsurface out of it. By cleaning the parent geometry less time is required to clean the mid surface and good feature capturing also can be obtained.
• we can remove the unwanted volume component from the geometry as we are working on the mid surface of the main component.
• Divide the geometry into certian parts to easy the work of taking out the mid surface. ( we can divide the geometry with various part attached to it )
• Defeaturing of the ribs. The rib should be defeatured to get a good mid surface out of it .

• Defeaturing of the rib

• If there are ribs in the component ( as shown in Figure 5) which are having some fillets, the mid surface of the rib would not be extracted in proper way, so we need to defeature the rib.

{Figure 5}

• To defeature the rib go into Geometry > defeature > surf fillets > provide the minimum radius and max radius accordingly > hit find ( as shown in Figure 6.)

{ Figure 6 }

• Hypermesh will find the fillets and highlight it. it will highlight the fillets between min radius and max radius ( As shown in the Figure 7 )

{ Figure 7 }

• Hit remove, hypermesh will remove the fillets. (As shown in figure 8 )

{ Figure 8 }

• Dividing the geometry

• Dividing the geometry will help to get a proper midsurface within less time and more efficient. ( As shown in Figure 9 i have divided the surface and imported it into another component )

{ Figure 9 }

Step 5 : Extracting the mid surface form the given component.

• Midsurface can be extracted in two ways auto midsurface and maunal mid surface.In auto mid surface there might be some issues in feature capturing and overlapping of surfaces , some complicated surfaces are not extracted in auto mid surface, so to eliminate such issues manual mid surface is prefered.

• Manual mid surface can be done as follows
• My offset method : First we need to check the thickness of the parent component. Accordingly we can offset one side of the parent geometry to the middle of its thickness. Refer Figure 10 as shown below check the thickness.

{ Figure 10 }

• To offset : Go in tools option > surfaceedit > offset > select the offset value > check for the colour normal (blue indicates offest will be inside and red indicates offset will be outside ) > then click on offset

• check whether the surface is offseted clearly or not . As shown in Figure 12 the mid surcae will be visible in a red line as the surface is free has a free edge

{ Figure 12 }

• Mid surface can be extracted with one more option , this option is more helpful when the surfaces are symetric to each other.In this component we have used the option to extrect the midsurface from the rib surface. As shown in Figure 13 to extract the mid surface from the rib go to geometry option > midsurface > click on the arrow pointing down change auto mid to final edit tools > select the surfaces side 1 and side 2 > set the option to result in the middle surface > click extract.

{ Figure 13 }

Mid surface image : After extracting the mid surace mid surace will look some what like shown in figure 14.

{ Figure 14 }

Step 6: check for the features were minimum length will fail, and make changes according to criteria.

• First check the dimension between two nodes of the surface and if the dimension is less or above the criteria the elemenet will fail for the given criteria so to avoid such issues adjust the surface such that it should not fail.
• Surface can be adjusted by toogling the line or extending the surfaces kus make sure that features are captured properly.
• Do manual clean up
• Tools used to manual clean up.
• geometry > quick edit > toggle ( toggle is used to remove unwanted point)
  geometry > quick edit > replace point ( to replace the unwanted points and lines, it is used to combine the geometry)
  geometry >quick edit>add or remove point( to remove the unwanted point)

Step 7: Meshing the component

• Criteria file setting : In order to mesh the midsurface first we input the given quality criteria and target element size as 4mm

• To set the criteria click on preferences > criteria file setting > input the criteria .(refer Figure15 )

{ Figure 15 } ( Given criteria )

• Perform meshing : We should mesh the complex surfaces first in order to maintain the proper mesh flow and make meshing easier. While meshing the midsurface we should make make sure that we maintain the trias percentage as low as possible. While meshing curved or complex surface if the mesh doesnot properly catch the surface then we should increase or decrease the node count so that mesh attaches the surface properly.
  

• To mesh click on 2D > automesh > select size abd bias > input given target element size > mixed element > mesh (refer Figure 16 )

{ Figure 16 }

• Refer figure 17 to understand how meshing is conducted.

{ Figure 17 }

This is how it will look after whole component is meshed properly ( Refer figure 18 )

{ Figure 18 }

Step 8: Check for the failing element in quality criteria & Fixing the failed element. The failed element are highlighted in yellow and red ( Refer Figure 19 )

{ Figure 19 }

• To check the failed element in mesh click on 2D > quality index
• In quality index you can see total number of elements failing as well as for what criteria they are failing that to you can see as shown in Figure 20

{ Figure 20 }

• To remove the element failing as well as decrease the tria concentration

• fix the trias and rotating quad. ( Refer Figure 21 )

  to fix trias and rotating go to 2D > quality index > cleanup tools
  place node : node of the element can be dragged
  combine tria: two tria can be combined
  element optimize: click on the element which are failed it will oplimizes automatically.
  smooth : smooth adjust the element size accordingly.
  drag tria : you candrag the tria element

{ Figure 21 }

• we can also fix the failing element manually by increasing or decreasing the distance or by changing the magnitude

• geometry > distance > select the node > give the distance according so that element will not fail. ( refer Figure 22 )

{ Figure 22 }

• tools > traslate> select the point and traslate .( refer figure 23 )

{ Figure 23 }

• There may be some other important parameter for tria management.
• No trias in corner or edges.
  No opposite trias.
  No back to back trias.
  No trias in fillet or hemming.
  No rotational quads.

Step 9 : Check for free edges

• There should not be any free edge in the componet as the meshing is then considered as bad mesh because there is no connectivity in the mesh due to free edge.
• check for the free edges, to check free edges go to tools > edges > select the component > free edge ( Refer figure 24 )

{ Figure 24 }

• free edges are shown in differenet component and are visible in red as shwon below ( refer figure 25 )

{ Figure 25 }

Step 10 : Assign thickness to mesh .

• After completion of meshing, now we assign the thickness to midsurface. thickness is assign to mid mesh such that it takes the thickness according to the parent geometry.
• For assigning the thickness we create the property and in property we add the thickness value .(refer Figure 26 )

{ Figure 26 }

• Now we create a component and in component we add a mesh of different thickness by using tool organize command. ( refer Figure 27 )
• create different components accoding to thickness.
• Move element to component with respective thickness.
• To add the element to that component.
• Go to tool > organize > collector > select the element > select desh component part which you make new component > move.

{ Figure 27 }

• Assign the property to the component by right clicking on the component and assign ( Refer Figure 28 )

{ Figure 28 }

Image of model after thickness is assigned to it. ( refer Figure 29 )

• As you see in figure 29 the colour of the rib will change according to the colour which we have assigned in the component. so by this we can confirm we have created component according to there thickness and when property applied itt will change its thickness accordingly.

{ Figure 29 }

Image of model after thickness is assigned to it. ( In 2D representation )

• To see the model in solid go to 2D detailed element representation tab. ( Refer figure 30 , 31 )
  

{ 2D detailed element representation tab }

{ figure 30 } { Figure 31}

Final model image :

Conclusion : Meshing was done successfully with assigning proper thickness to each and every component.