Defining a new shell

Each shell is defined as a closed polygon consisting of straight or curved lines.

The procedure to define a shell

1. Open service Structure.

2. Start function Shells.

3. Fill in the parameters – see chapter Shell parameters.

4. Confirm with [OK].

5. Input the vertices of the polygon.

6. If the defined polygon is not closed, the program tries to close it automatically.

Tip: If you want to define a curved 2D member, it may be very useful to input the shape-defining curves in advance as normal lines (service Structure > Drawing tools > Line). See also Sample shells.

In addition to a general shell, it is possible to use special functions for the input of a surface of revolution and swept surface.

Swept surface

This shell is defined by a master curve and a line or curve along which the master curve is translated (swept). This translation generates the final shape.

The procedure to input a new swept surface

1. Open service Structure.

2. Expand branch 2D members.

3. Select and start function Shell – swept surface.

4. Input the parameters (se chapter Basic slab types).

5. Define the master curve. End its definition with [Esc].

6. Input the curve along which the master curve will be swept. End its definition with [Esc].

7. Close the function.

Surface of revolution

The procedure to input a new surface of revolution

1. Open service Structure.

2. Expand branch 2D members.

3. Select and start function Shell – surface of revolution.

4. Input the parameters (se chapter Basic slab types).

5. Define the line/curve that will rotate around the axis and thus define the surface.

6. Once the master curve is input, a dialogue opens on the screen.

7. Define the angle of rotation.

8. Define the way the axis of the solid will be defined (see the table above).

9. Confirm the settings in the dialogue.

10. Input the centre of rotation (and depending on the type of the definition of the axis, input other required points).

11. Close the function.