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

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), 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 characteristics

5. Remail flexible down to -150°C

6. High rigidity

7. Good impact resistance

2D Shell Meshing of the CAR side door inner panel for component level analysis using FEA tool Hypermesh:

2. Finite Element Analysis

The finite element method is a numerical technique for obtaining an approximate solution to various engineering problems. Three phases do FEA (Finite Element Analysis).

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 a suitable material ID and boundary conditions. ANSA And Hyper-mesh are the example tools, and in this project, Hypermesh is used. Hypermesh interface.

Above all types of elements are done under user-defined Quality criteria. For example, refer to table1.1.

Element Quality Criteria:

S.No Quality Criteria Value

1 Target/Average length - 5

2 Minimum Length - 2

3 Maximum Length - 6

4 Aspect - 5

5 Warpage - 15

6 Skewness - 45

7 Minimum Quad Angle - 45

8 Maximum Quad Angle - 135

9 Minimum Tria Angle - 20

10 Maximum Tria Angle - 120

11 Tria Percentage - 10

12 Taper - 0.5

Table1.1: Element Quality Criteria

Procedure:

The meshing is done by following steps

1. Import Side_door.hm into 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 into Hypermesh: file>open>model, browse the file and open.

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

2. CAD Geometry clean-up and topology: The given model undergoes a geometry check in this step. Where all the defects such as collapsed faces, free edges, T-edges are clear.

Split the surfaces for better mesh and time conjunctions.

Tools used in topology

Tools>Edge Edit Panel

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

In the given model, there are so many defects. Fillets that are very small and should be defeated.

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 the 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 finding process.

c. By clicking on the remove, all selected fillets will be removed.

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 "dragline".

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. When possible, merge the input lines into smooth lines 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 were 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 entities and measure (Geom>distance). We found different thicknesses on each feature. For the parent, we have T=2.8 units. Simply the extraction of the mid surface. models divided into two components

The mid surface is done by manually using offset (Geom> surface edit> offset).

Steps

a. select offset

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

c . select the surface and duplicate the same surface

d. input the value which is half of the Thickness

e. to check the direction, click on vector normal to 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. (Geom>midsurface>final edit tool) show panel below

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 mid surface.

By default, only two surfaces that are selected with the side1 and side2 surf selectors are considered.

To take offset directions of the adjacent pre-existing mid surfaces, select the use adjacent mid surfaces checkbox.

To allow modifying pre-existing adjacent mid surfaces, 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: 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 two edges to equivalence together. Control which edge to retain and which to move.

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

5. Shell Meshing: Before meshing, Assign given element Quality criteria into hypermesh by Preferences>criteria file setting.

Start meshing Process by Automesh (2D>Automesh )

steps to mesh

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

b. select size and bias and select mesh size, which is Target/Average length 4. Use the Size and Bias subpanel to perform size and bias meshing, a flexible and powerful meshing method. A minimum of inputs is 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 mesh to break up the areas defined by the selected elements into logical groupings with mesh controls set for each group boundary.

c. Select the mesh type as mixed (Quad, Tria, mixed, R tria etc.) and click on aline and size to get proper mesh near features.

Click on the mesh or middle mouse button.

Modify mesh flow by changing surfaces to elements and selecting the elements. Make sure that while doing mesh, all the element Quality criteria must be satisfied. Avoid maxim opposite traits.

The starting point and endpoint for components to achieve better flow.

Remove all quality failing elements by smoothing, changing distance, angle b/w the nodes of failing elements we can see 0 (0.0%) elements are failed.

Find Free Edges: Use the Edges panel to find the free edges in a group of shell elements, find "T" connections in a group of shell elements. Free edges are defined as a pair of nodes identifying an element edge that is not shared with another element. Free edges are normally found around the outer perimeter of a part or around openings within the part.

Free edges found in your model are displayed as red plot elements in their own component called ^edges. Free edges within a field of elements typically indicate a discontinuity within the mesh. Such discontinuities may be intentional, such as crack modelling for durability simulation, or unintentional, due to geometry discontinuities, meshing methods or component boundaries. In cases 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". You can use equivalence to remove the coincident nodes, based on a search tolerance that you specify.

Steps

a. Go to tools>Edge

b. Select the elements whose associated edges you wish to find.

c. Specify a spherical search radius around each node in the selected component or group of elements. If multiple nodes are found within this search tolerance they are considered coincident and can be resolved with the equivalence function. tolerance is approximately 60% to 70% of the Thickness

d. Click on preview equivalence, and equivalence to join nodes.

e. Click on find edges to see the free edges in Red colour for mesh.

Result:

Shell (2-D) mesh is done Successfully for the Side Door Panel model by eliminating geometrical errors and considering the given element quality criteria also assigning Thickness using Hypermesh.