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

AIM:To create the shell (2-D) meshing for the Car Side Door Panel by eliminating geometrical errors and considering the given element quality criteria using Hypermesh.

Introduction:

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 degrees

3. Very good heat resistance

4. good processing characteristics

5. High rigidity

6.Good impact resistance

FIG: car door side panel

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 (Finite Element Analysis) is done by three phases.

1. Pre-processing

2. Solution

3. post-Processing

This project comes under Pre-processing. The goals of Pre-processing are to develop an appropriate finite element mesh, assign suitable material ID and boundary conditions. ANSA And Hyper-mesh are the example tools and in this project Hypermesh

Above all types of elements are done under user defined Quality criteria. for example refer table1.1.

Element Quality 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:

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.hm in toHypermesh :file >>open >>model>>browse the file and open. in the figure 1.1 shows the model.

From the imported file we can see so many features such as Ribs, Locators etc. So that this component has different thickness on each feature.

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. In the fig.2.1 show description on surface.

Tools used in topology

Tools>>Edge Edit Panel

A. Equivalence (multiple edges at a time) Search surfaces for pairs of free edges and combine into shared edges

B. Toggle (edge pair at a time) Select an edge; equivalences with other free edges found within a user specified tolerance

C. Replace (1 edge pair at a time) Select 2 edges to equivalence together. Control which edge to retain and which to move.

D. Geom >>>Surfaces>>>Ruled or Geom>>> Quick edit >>>filler surface or 2d>>> spline surfaces only (to create missing surfaces).

Defeature all small fillets by using steps

a. Geom>>Defeature>>surface fillets.

b. Use the Surf Fillets subpanel to identify and remove surface fillets (curved surfaces that create a smooth transition between relatively perpendicular geometric entities). You can identify fillets based on radius, because fillets are always uniform arcs. You can also select a fillet by picking one of the edges that it connects. Once found, fillets can be removed using tools that display automatically after the find process.

c.By clicking on remove all selected fillets will be removed. The below fig shows the fillets removed by surface fillets.

Fill missing surfaces using line drag:Use the Drag Along 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. Show in the figure

3. Mid-surface extraction:

The given model is a side door panel and before going to the Mid surface extraction check for thickness of entities and measure(Geom>>distance). We found different thickness on each feature. For the parent we have T 2.8 units. To simply extraction of mid surface. models divided in to two components shown in the fig

Mid surface is done by manually using offset (Geom&>>>surface edit>>> offset). offset panel shown in the fig below

Steps

a. select offset

b.Offset moves the selected surfaces without retaining their connections to surrounding geometry.

c . select the surface and make a duplicate of same surface

d. input the value which is half of the thickness

fig: MID SURFACE EXTRACTION USING OFFSET COMMAND

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.

final midsurface of the model

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.

tools to Defeaturing

A. Toggle edge

Left-click a free edge (red) to make it shared (green), or a shared edge to make it suppressed (blue).

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. For example, toggling a free edge to a shared edge requires the presence of a similar edge within the distance you specify in the tolerance field.

B. Replace (1 edge pair at a time) Select 2 edges to equivalence together. Control which edge to retain and which to move.

C. Geom>>Quick edit >> filler surface (to create missing surfaces) .

GENERATING THE MESH :Before meshing Assign given element Quality criteria in to hypermesh by Preferences criteria file setting shown in Fig

Target Element Length = 4 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	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

Start meshing Process by Automesh (2D >>Automesh )

steps to mesh

a. Select surfaces for initial mesh and for remesh select elements.

b. select size and bias abd 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 encountered in the geometry. When using existing finite elements as the basis for mesh generation, feature recognition 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 (Quad, Tria, mixed, R tria etc) and clock on alin and size in order to get proper mesh near features.

click on mesh or middle mouse button

Modify mesh flow 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.

BY given of above values to meshing the components

After completing of mid surface exact ,then we go from the mesh the component

2D-automesh optionselested-then we go from while surf/elements option of doing the mesh.

shortcut key f12 (mesh)

And selected of mesh type options

BY the given of parameters values in hyper mesh

Then go with above of display screen option- preference selected-criteria file setting option

The option shows the failure of elements in the spot of doing the mesh

FINAL MESH OF THE COMPONENT

ASSIGN THICKNESS:(AUTOMATIC THICKNESS) :

In order to represent FEA model similar to cad model , thickness will assiged to the 2d shell elements

With the help of parent geometry , thickness will be assigned manually and automatically to the shell elements

THICKNESS OF THE COMPONENTS

PROPERTIES OF THE COMPONENTS

As assigned the thickness to the model :

View in as 2D detail representation element

CONCLUSION :

Generated manual midsurface and geometry clean up

Generated mesh on the given component with low tria concentration

And finally the given quality parameters are should passed

Finally assigned automatic thickness to 2D shell elements

FIG: MODEL AFTER ASSIGNING AUTOMATED THICKNESS