Week 12:Project-1-Meshing of Door Inner Panel Challenge
AIM:
To hypermesh the given challenge.
OBJECTIVE:
To create the shell 2-D meshing for the Car Side Door pannel by eliminating geometrical errors and considering the given element quality criteria using Hypermesh.
THEORY:
1.Car Side Door Panel:
The side door panel is the plastic part materials used for the door panel are acrylonitrile-Butadiene-Styrene(ABS), ABS/Polycarbonate alloys, Polypropylene(PP).
PROPERTIES:
1.High weathering resistance.
2.High strength and toughness up to 140°C.
3.Very good heat resistance.
4.Good processing characterstics.
5.Remail flexible down to -150°C.
6.High Rigidity
7.Good impact resistance.
2.Finite Element Analysis:
The finite element method is a numerical technique for obtaining an approximate solution to a wide variety of engineering problems. FEA is done by three phases. They are,
1.Pre-Processing
2.Solution
3.Post-Processing
This project is comes under Pre-Processing. The goals of pre-processing are to develop an appropriate finite element mesh, assign suitable material ID and boundary conditions.
PROCEDURE:
The meshing is done by following steps,
1.Import side_door_panel.hm in to Hypermesh.
2.CAD geometry clean up and topology.
3.Mid-Surface extraction
4.Defeaturing
5.Shell Meshing
6.Creating properties and Thickness assigning.
1.Import side_door_panel.hm in to Hypermesh:
File> open > model, browse the file and open.
From the imported file we can see so many features. So that this component has different thickness on each future.
2.CAD geometry clean up and topology:
In this step the given model undergoes geometry check. Where all the defects such as collapsed faces, cracks, free edges, T-Edges are clear.
Tools used in topology: Tools > Edge Edit panel.
I.Equivalence search surfaces of pairs of free edges and combine into shared edges.
II.Toggle Select an edge equivalences with other free edges found with in a user specified tolerance.
III.Replace Select 2 edges to equivalence together. Control which edge to retain and which to move.
IV. Geom > Surfaces > Ruled or Geom > Quick edit > Filler surface or 2D > spline > surfaces only.
In the given model there are so many defects. Fillets which are small and should be defeated.
Steps:
a.Geom > Defeature > Surface fillets.
b.Use the Surf Fillets subpanel to identify and remove surface fillets. We can identify fillets based on radius because fillets are always uniform arcs.
We can also select a fillet by piciking one of the edges that it connects. Once found fillets can be removed using tools that display automaticaly after the find process.
c.By clicking on remove all selected fillets will be removed.
Fill missing surfaces using line drag:
Use the Drag alone line subpanel to create surfaces by dragging lines or a node list along another line called the drag line.
STEPS:
a.Select the lines or node list to drag
b.Select the lines that the drag will follow. This can also be a series of connected lines.
c.Merge the input lines into smooth lines when possible and create a surface for each group that forms a tangentially continuous line. Clear this checkbox to create a surface for each input line with shared edges connecting surfaces where relevant.
d.Choose where to organize the resulting surface component.
3.Mid-Surface Extraction:
The given model is a side door panel and before going to the mid-surface extraction check for thickness of entites and measure. We found different thickness on each feature. For the parent we have T = 2.8 units. To simply extraction of mid surface models are divided in to two components.
Mid surface is done by manually using offset panel.
STEPS:
a.Select Offsets.
b.Offset moves the selected surfaces without retaining their connections to surronding geometry.
c.Select the surface and make a duplicate of same surface.
d.Input the value which is half of the thickness.
e.To check the direction click on vector normal so that we can see the offset direction also one can change the direction by reverse normal.
For all ribs extraction of mid one file final edit tool from Midsurface.
Select a surface that represents one side of the solid.
Select a surface that represents the second side of the solid.
Select extraction options accordingly to define which surfaces to take into account when constructing midsurface.
By default only two surfaces that are selected with the side1 and side2 surf selectors are considered.
To take into account offset directions of the adjacent pre-existing midsurfaces select the use adjacent midsurfaces checkbox.
To allow modifying pre-exisitng adjacent midsurfaces select the combine with adjacent mid surfaces checkbox.
Extend all the ribs to the base surface using Extend.
Select the line of Extend a surface over edges to another surface.
Select the target surface.
4.Defeaturing:
Update the criteria length as per given element quality criteria which is Target / Average length 5. Removing all unnecessary edges fillet radiuses etc... Also maintain distance between two edges or nodes not less than Minimum length of 2.
A.Toggle Edge:
Left click a free edge to make it shared or a shared edge to make it supressed.
Right click a suppressed edge to make it shared or a shared edge to make it free.
In either case the edge must meet the criteria for the type of edge you wish to change it to.
B.Replace Select 2 edges to equivalence together.Control which edge to retain and which to move.
C.Geom > Quick Edit > Filler surface.
5.Shell Meshiing:
Before meshing assign given element quality criteria in to hypermesh by preference > criteria file setting.
Start meshing process:
STEPS:
a.Select surfaces for inital mesh and for remesh select elements.
b.Select size and bias and select mesh size which is Target / Average length 5. Use the size and bias subpanel to perform size and bias meshing a flexible and powerful meshing method.
A minimum of inputs are required for the element criteria settings. The algorithm options set preferences on how to handle certain situations when encountred in the geometry.
When using existing finite elements as the basis for mesh generation, feature recognization settings allow the mesher to break up the areas defined by the selected elements into logical groupings with mesh controls set for each group boundary.
c.Select the type of mesh as mixed and clock on alin and size in order to get proper mesh near features.
Clock on mesh or middle mouse button. Modify mesh flows by changing surfaces to elements and select the elements. Make sure that while doing mesh all the element quality criteria must be satisfied. Avoid maxim opposite traits.
Starting point and ending point for components to achieve better flow.
Remove all quality falling elements by smoothing by changing distance, angle between the nodes of falling elements we can see 0 elements are failed.
6.Creating Properties and Thickness assiging:
Not only property we can create components material, cross section etc... by right click on tab area and select requirements.
Before creating the properties we need to create components for elements as per the different thickness. Right click on the Tab area and select component to create components.
Create the property as per the components thickness. To create right click on the tab area and select property to create properties.
a.Select property we can see the properties in the tab area.
b.Clicking on the property and rename change the thickeness, select material, card image and etc... For each component we need to create property.
Each property card has following properties:
Slover Keyboard
ID
color
Card image
Thickness T etc...
Assign properties to each component by right click on Comp > assign > select property. In the graphics area we can see the model after applying the properties.
OUTPUT:
Fine Free Edges:
Free edges found in our model are displayed as red plot elements in their own component called edges. Free edges within a field of elements typically indicate a discontiunity within the mesh. In case where the mesh has a discontinuity there will typically be more than one node at approximately the same location in space. Such nodes are called coincident. We can equivalence to remove the coincident nodes based on a search tolerance that we specify.
STEPS:
a.Go to Tools > Edge.
b.Select the elements whose associated edges we wish to find.
c.Specify a spherical search radius around each node in the selected component or group of elements. If multiple nodes are ofund within this search tolerance they are consideed coincident and can be resolved with the equivalence function, tolerance is approx of 60 to 70 % of the thickness.
d.Click on preview equivalence and equivalance to join nodes.
e.Click on find edges to see the free edges in Red color for mesh.
Check for normals:
STEPS:
a.use the elements subpanel to display and reverse the normals of elements. Select elements indirectly by components or directly by elements or elect to have all of the displayed 2D elements selected automaticaly.
Click display to review the current normal orientation of the selected elements. Optinally click reverse to flip the normals to the opposite side.
b.Adjust normals based on the orientation method you specified.
c.Flip all of the normals of the selected elements.
Shell mesh is done sucessfully for side door panel model by eliminating geometrical errors and considering the given element quality criteria also assigning thickness using Hypermesh.
OBSERVATION:
Thus the shell 2-D meshing for the Car Side Door pannel by eliminating geometrical errors and considering the given element quality criteria using Hypermesh is obtained sucessfully.
RESULT:
Thus the given challenge is determined sucessfully.