(tutorial-user-defined-sg-2d-cross-section)=
# Cross-section with arbitrary shape (2D SG)

## Steps

### Step 1: Set work directory

**Menu** > **File** > **Set Work Directory...**.
Select the directory where you want to put all related files, .cae, .inp, .sc, etc.


### Step 2: Create materials

Create two materials, "Material-1" and "Material-2", with arbitrary material properties.


### Step 3: Create composite sections

User can create layups using functions described in section 3.3, or using Abaqus’s own functions by hand, which is described below.

**Module** > **Property** > **Create Section**.
Create three **Solid** > **Composite** sections, "Layup-1", "Layup-2" and "Layup-3", with the following configs.

```{figure} /_static/images/cs-any-edit-comp-solid-section-layup-1.png
:align: center

Composite section Layup-1.
```

```{figure} /_static/images/cs-any-edit-comp-solid-section-layup-2.png
:align: center

Composite section Layup-2.
```

```{figure} /_static/images/cs-any-edit-comp-solid-section-layup-3.png
:align: center

Composite section Layup-3.
```

Note here that the thickness of each layer should be actual thickness instead of relative thickness.


### Step 4: Draw the general shape

According to the coordinates convention in SwiftComp, the X-axis is along the beam reference line and the cross-section is in the Y-Z plane.
Thus we need to first set our workplane to Y-Z plane.
Click **Work plane** ![](../../../../assets/icons/sc_wp_small.png), give a **New Part Name**, and select **2D** as the **SG Dimension**.
Click **OK**.

```{figure} /_static/images/cs-any-set-sketch-plane-db.png
:align: center

Set work plane.
```

```{figure} /_static/images/cs-any-sketch-plane.png
:align: center

After setting the work plane.
```

In **Module** > **Part**, click **Create Shell: Planar**, following the prompt, select the datum plane and the datum axis.

Sketch the shape shown below, with dimensions marked in the figure.

```{figure} /_static/images/cs-any-sketch.png
:align: center

Sketch the geometry.
```

Click **Done**, then the part will be generated.

Next we need to divide this part into four segments.
Use **Partition Face: Sketch** to create the four segments as shown below.

```{figure} /_static/images/cs-any-geo-general.png
:align: center

Partition the geometry.
```


### Step 5: Assign layups

First we will assign the layup for the top segment.

Click **Assign Layups** ![](../../../../assets/icons/sg_2d_laminate_small.png) to open the dialog box.
Pick the area 1, pick the baseline 2 and select section "Layup-1".
Click **OK**.

```{figure} /_static/images/cs-any-assign-layups-db-2.png
:align: center
```

```{figure} /_static/images/cs-any-assign-layups-select.png
:align: center
```

```{figure} /_static/images/cs-any-assign-layups-done.png
:align: center
```


Next, assign the layup for the segment on the left.
Pick the area 1, baseline 2, opposite boundary 3, give 20 sampling points and select section "Layup-1".
Click **OK**.

```{figure} /_static/images/cs-any-assign-layups-2-db.png
:align: center
```

```{figure} /_static/images/cs-any-assign-layups-2-select.png
:align: center
```

```{figure} /_static/images/cs-any-assign-layups-2-done.png
:align: center
```


We can do the same for the rest two segments, except that we use "Layup-3" for the right segment.

```{figure} /_static/images/cs-any-assign-layups-all-done.png
:align: center
```


The color may change for some layers after assigning new layups.
This is due to new sections created in "Layup-3", causing the order of the section list to change, so that the color map also changes.


### Step 6: Delete layups

If users find that some layup is assigned mistakenly, it can be deleted and re-assigned.
For instance, we want to re-assign the layup for the left segment.
Click **Erase Layups** ![](../../../../assets/icons/sg_2d_laminate_erase_small.png).
In the dialog box pick the same baseline used for assigning the layup.
Click **OK**.

Once done, user can assign a new layup for the empty segment.
Here we assign the "Layup-2".

```{figure} /_static/images/cs-any-reassign-layup-2.png
:align: center
```


### Step 7: Assign local coordinates

In **Module** > **Property**, use **Assign Material Orientation**.

For a shell part in Abaqus, we can only have axis 1 and 2 in the cross-section plane.
Thus we will make axis 1 and 2 as the local $y_2$ and $y_3$ axis in SwiftComp convention respectively.
Here we will keep axis 2 ($y_3$) perpendicular to the outer profile edges and pointing outwards.
User can also let axis 2 point inward, as long as the local orientation keeps consistency with the global coordinate and fiber orientations defined by users.

Following the prompt, we first select the top segement to be assigned a local material
orientation, and click **Done**.
Then in the prompt area, click **Use Default Orientation or Other Method**.
In the **Edit Material Orientation** dialog box, select **Discrete** as the **Orientation Definition**.
Then click **Define...** to open the **Edit Discrete Orientation** dialog box.

In the **Normal axis definition** choose **Vector (i,j,k)**, and set the vector (1.0, 0.0, 0.0).
For **Primary Axis**, select **1** as the **Primary axis direction** and **Edges** as the **Primary axis definition**.
Click **Edit Edges...** to select the light blue edge shown in the figure below, then click **Done**.
Use **Flip Direction** to make the axis pointing to the right if necessary.
Click **Continue...** then **OK** to finish this assignment.

Do the same procedure for the rest three segments.
Some steps may not be exactly the same.
The only requirement is to make sure that the axis 2 pointing outwards.

```{figure} /_static/images/cs-any-edit-material-orient-db.png
:align: center
```

```{figure} /_static/images/cs-any-edit-discrete-orient-db.png
:align: center
```

```{figure} /_static/images/cs-any-edit-discrete-orient-select.png
:align: center
```

Once done, the local orientations should look like the same as the figure shown below.

```{figure} /_static/images/cs-any-local-orient-final.png
:align: center
```


### Step 8: Create assembly

In **Module** > **Assembly**, click **Create Instance** and select the part created before.

```{figure} /_static/images/cs-any-assembly.png
:align: center
```


### Step 9: Mesh

In **Module** > **Mesh**, first choose **Part** as the **Object**.
Then click **Seed Part**.
In the **Global Seeds** dialog box, set **Approximate global size** to 1.

```{figure} /_static/images/cs-any-mesh-seed-db.png
:align: center
```

Click **Mesh Part**, then click **Yes** in the prompt area.

```{figure} /_static/images/cs-any-mesh-done.png
:align: center
```


### Step 10: Write Abaqus input file

In **Module** > **Job**, click **Create Job**.

In the **Create Job** dialog box, set **Name** to "Job-1".
In the model tree, right click "Job-1", click **Write Input**, then an Abaqus input file "Job-1.inp" will be created.


### Step 11: Homogenization

Click **Homogenization** button ![](../../../../assets/icons/sc_homo_small.png).
In the dialog box, choose **Model source** > **Input file**.
For **Abaqus input file**, select the abaqus input we just created, "Job-1.inp".
Choose **Macroscopic model** > **Dimension** > **1D (Beam)**.
Choose **Options** > **Elemental orientation** > **Local**.
Then click **OK**.

Note: Since we used discrete local orientations, local coordinate systems for each element are calculated only when writing the Abaqus input file.
Thus user can only choose **Input file** as the **Model source** to do the homogenization.


```{figure} /_static/images/cs-any-beam-homog-db.png
:align: center
```

After a certain time, depending on the model size, SwiftComp will finish computing the cross-sectional properties and show the results in the notepad.
If no error occurs, close the notepad and the process will end.

```{figure} /_static/images/cs-any-beam-homog-output.png
:align: center
```

If error messages pop out, or an empty notepad file appears, please refer to the command line window for more information.


## Related

- [](#guide-sg-2d-laminate)