( a) Geometry -> Quick edit -> Filler surfaces, and select the free edge

(b) go to Geometry -> Surfaces -> Ruled surfaces, select the first and second line lists and click create.

• Measure thickness of the model

After fixing geometrical errors in parent geometry we need to measure the thickness of the model in order to take mid-surface

We have to create some random nodes on both top and bottom surfaces, which are perpendicular to each other. We can create these nodes by going into the project option (Shift+F7 is the shortcut key for project).

In the project we can select the surface.

Long press of the left click on your mouse so that the top surface will be highlighted now you can select the nodes on the top surface .

After selecting the nodes right click on the nodes and duplicate the nodes for .

We have to duplicate the nodes two times since the nodes should be presented on the top and bottom surface.

select the bottom surface.

click on the project .

We can switch the surface into wireframe mode.

We can measure the thickness by choosing the distance command from the geometry .

Click on the distance tab. Select the two nodes (one from top surface and another one from Bottom surface )

The thickness of the surface will be displayed at distance .

3 ) Extraction of Mid-Surface by various techniques

since Mainbody of side door is of uniform thickness of 2.8 mm, we can use offset option to extract mid-surface,

At first we need to create a new component and rename it as side-door mid-surface, and make it as current component.

Go to Geometry -> surface edit -> offset

choose continuous offset , select top or bottom surface of main body by face option and duplicate the surface to current component and input the offset value. check the vector normal,

and click offset to extract mid-surface.

Main body mid-surface

Extraction of mid surface for varying thickness ribs:-

We will create a midline for the varying thickness rib, by using that line we will be able to trim the base mid surface which is offsetted manually. A shared edge will form on the base mid surface, by using the ruled option from the surface we will be able to create a surface in between the midline and the shared edge(the line in green color ).

A mid line should be created for the rib .

Midline option is presented in lines command{Geom->Lines->midline}.

We have to select the line list 1&2 and click on create .

A midline is created as shown in the below picture.

We have to trim the base mid surface with respect to that line .

We have to go to surface edit which is in geometry (Shift+F9 is the shortcut key for surface edit).

We have to choose trim with lines .

Select the surface which is to be trimmed .

Select the midline and click on trim.

A shared edge will form on the base surface.

Now we have to create a surface between the shared edge(green line when we are in “by topo” mode ) and the midline.

We can use the ruled option from the surfaces in geometry {Geom->surfaces->Ruled}.

We can select the shared edge as one linelist and midline as the 2nd linelist and click on create.

A surface is created between the shared edge and midline. The created surface is the mid surface for the Varying thickness rib.

Mid-surface of varying thickness rib

Extraction of mid-surface by using Final edit tool in Mid-surface panel

Go to Geometry -> Midsurface -> select Final edit tool, select side 1 and side 2 of the rib and click on extract.

Mid-surface of rib created using final edit tools

To extend mid-surface to the Main mid-surface body

Go to Geometry -> surface edit -> extend -> choose extend over edges option. select the free edge needed to be extended and select the target surface.

After extending rib to the Main mid-surface

Thus by using all the above-mentioned methods we extracted mid-surface of side-door plastic component.

Final Mid-surface of side door model

4 ) Perform 2D meshing on the Mid-Surface

First we need to enter the element quality criteria, go to Preferences -> Criteria file settings and enter the values.

Figure below shows the element quality parameters given for the model.

To create a mesh on the mid-surface, go to 2D -> Automesh -> select the surface and choose the element size as 4 and select type of elements -> mesh

we can change the element density by increasing or decreasing the number of nodes, left mouse click to increase and right mouse click to decrease.

To Rotate the nodes of elements around the holes in order to capture the hole properly

figure below shows capture of hole before rotation like a diamond shape

First we need to create a centre node for the hole as a base point for rotation. go to Geometry -> Nodes -> arc centre -> select the line around holes -> create

Now in order to rotate the nodes to make it parallel to the edge, go to Tools -> Rotate -> select the nodes around the holes

then select the plane by picking nodes N1, N2, N3 and select the center node as base point, give the angle for rotation and click rotate+/- to make it parallel to the edge.

Finally remesh the region by anchoring the nodes arond the hole. go to 2D -> automesh -> select the elements, select anchor nodes -> Mesh

figure below shows final result after rotation and remesh

Handling of Tria Elements

Tria elements are the elements formed with 3 nodes. There are certain rules considered while handling Tria elements.

you can use drag tria element tool to drag and combine opposite tria elements ,also we can use swap edge tool to swap tria from free edges.

5 ) Clearing the Elemental failure as per Quality Criteria

To clear Element failures we can use smooth option in clean up tools. ( 2D -> quality index -> Cleanup tools )

figure below shows element failing for max quad angle

In order to clear the max quad angle error we need to chnage the distance between nodes in such a way that angle between the edges should be reduced.

go to Geometry -> Distance ( shortcut F4 ) -> select 2 nodes and change the distance value.

figure below shows the max quad angle of the element is cleared after changing the distance between nodes from 4.001 to 3.8

Warpage:

Whenever you have a quad element in two different planes then you will have your element failing for Warpage. Ideally, your element should be in a single plane, when they are in two different planes if you split the quad along the diagonal and measure the angle between the normals it will give your element Warp angle. Warp angle is the angle of plane deviation in your element which is also known as Warpage.

figure below shows element failing for warpage

In order to fix warpage you can move the nodes in the normal direction so that they stay in the same plane where the other nodes are, else you can split the element and have Trias. The Tria element will not have Warpage as they form in one plane.

To move the nodes of element, go to Tools -> Translate -> select the node to move and select the plane by choosing nodes N1, N2, N3. then click on translate +/- with respect to the direction we need to move the node to clear the warpage failure.

Mesh Edit tool

When we are facing an issue with extending a rib to the base surface then this option can be used to connect the elements of two different surfaces with nodal connectivity (mostly used in the rib portions). It is presented in the 2d panel.

When we click on the mesh edit tab. The meshedit tool command looks like the picture below .

Figure below shows there is no connectivity between elements in the ribs and base surface

Imprint option can be used to project the mesh in order to ensure connectivity.

It will imprint the nodes or elements of a surface to the other surface .

In source we can select the comps , elems , node list for imprint. Destination also will have these three selections.

select source node as unconnected nodes from the ribs and destination as elements from the base surface

After obtaining connections

Side Door Panel After clearing Element failures

Check for free edges in the model

There will be free edges present in the model if there is no proper connectivity between elements, to check

go to Tools -> edges -> select all elements of the model and click on find free edges.

figure below shows free edges present in the model

In order to fix the free edges present in the model, select all elements and enter toletrnce value and click preview equivalence,

nodes which are going to be equivalenced will be highlighted as shown in figure below and then press equivalence

After fixing free edges in the model

Chech for Normals for the Elements

Go to Tools -> Normals -> select all elements in the model -> click on display

figure below shows some elements have different normals ( red colour) in the model

so in order to change the normals of elements we can click on adjust button on hte panel or individually select elements and ckick on reverse option.

so that every element in one face should be in one clour.

After fixing Normals of the model

6 ) Assigning thickness and converting shell elements to Solid elements

In the final stage, we need to convert the 2D shell elements into Solid elements by assigning thickness to the shell element.

First, we need to assign property for Main body of side door panel, by right click -> create- > Property and enter thickness value of 2.8 mm in the property card. and assign the property to the elements in Mainbody.

All the ribs and other features have different thickness, so we need to create a new component for ribs by right click -> Create -> component,

then we need to move elements of the ribs into the new component created using Tools -> Organize- > select the elements of rib -> choose destination component as new component created for rib.

After moving elements of rib to a new component

then assign thickness to the component by creating a new property card and assign to the elements.

Thus we created several components and assign thickness to them. figure below shows total components and property card created for side door model

To visualize the thickness assigned to the shell elements switch on 2D detailed element representation option.

Solid representation of side door model

RESULT

Performed pre-processing of plastic components of car side door model. steps carried out in this project are,