Drawing planes are used to add geometry to the model. Instead of the freedom of adding the geometry in 3D space, the geometry is always snapped into the plane. In addition to the obvious advantage of being able to draw flat geometry, regions created with construction objects drawn in a plane can be meshed with the 2D mesher. See the page Meshing Overview: Meshing Hand-built Models: 2D Mesh Generation for details.
When using a drawing plane, the FEA Editor environment is in sketch mode. Hence, the terminology sketch and drawing plane will be used interchangeably.
Additional planes can be created by using Draw Draw
New Sketch Plane, or by right-clicking on the Planes branch of the tree view and choosing New Plane.
You can select between the three planes parallel to the global axes (XY, YZ or XZ). You can also select the Advanced option or the 3 points option to define an off-axis plane. Activating the Use Offset check box will allow you to offset one of the global planes from the origin. A positive offset places the plane in the positive direction. For example to draw in the X=10 plane, select the YZ option, activate the Use Offset check box and type 10 in the adjacent field.
To enter sketch mode to draw on a plane, right-click the desired drawing plane in the tree view and choose Sketch. When in sketch mode, a grid will appear in the display area and the drawing plane is shown in bold in the tree view. All sketching will be done in this plane. The grid can be turned off by right-clicking on the plane in the tree view and clearing Visibility. The spacing of the grid can be customized on the
Options
Sketching tab.
Geometry is added to the sketch just like any other geometry: use the commands on Draw and Design panel of the Draw tab. All properties such as part, surface, and layer number, and any object-specific input, are used in the sketch mode just like it is in the 3D mode. (See the page Adding Geometry for details.) The only real difference between adding these objects in 3D mode versus adding them in sketch mode is whether the entered points snap to the drawing plane or not.
When drawing sketch entities, if the cursor is close to a grid point, a lock icon will appear on the cursor. If you click, the item you are drawing will be snapped to that grid point. Likewise, you can snap the new geometry to existing geometry. The points will be projected into the drawing plane.
When an item is added to a sketch, a branch is created under the appropriate part that lists the drawing plane, and this branch includes an entry for each item drawn in that sketch. Click the drawing plane entry under the part to highlight the corresponding items.
To exit sketch mode, right-click the drawing plane and deactivate Sketch. Also, activating the sketch mode for another plane will deactivate the sketch mode for the current plane.
Here are the ways to copy items or sketches to other sketches:
There are situations in which a construction object is not in a drawing plane, so the tree view lists the item as a 3D object. Some commands are not available on 3D construction objects, such as 2D meshing. These 3D objects can be copied to a sketch as follows:
Note that the original 3D construction object is not projected into the drawing plane. Therefore, the object should lie in the plane into which it is being pasted.
The cross sectional properties of a sketch can be calculated. The guidelines for the sketch or sketches are as follows:
(a) Two overlapping regions (above) are supported by the 2D Moment of Inertia. The overlapping region between the square and the circle becomes a hole in the cross section. The calculations are based on shaded the regions (below).
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(b) Two regions that do not overlap (above) are not supported by the 2D Moment of Inertia. The problem areas are identified with the inverted triangles (below) when the command is executed. To calculate this area, remove the line in common between the square and the semi-circle. (Alternatively, a duplicate line - one for the square and one for the semi-circle --- could be used. For example, the duplicate would be required if the square and semi-circle were on separate parts and the two regions were going to be meshed with the 2D mesh engine.)
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Once the sketches are made, either select the plane in the Planes branch of the tree view or select the plane entries in the tree view under the part, then right-click, and choose 2D Moment of Inertia. Selecting the Planes branch is equivalent to selecting each of the individual planes appearing under each part. The calculator will split the combined sketches into a series of horizontal rectangular strips and perform a numerical integration based on these strips. The results are given in the 2D Moment of Inertia Results dialog and consist of the following:
A construction vertex is also added to the model at the location of the center of gravity.
The Save Results dialog will appear when the Save button is clicked. Choose the file name and location of the area calculation results. Activate the Append check box on the Save Results dialog before clicking the Save button to append the current results to an existing file. Otherwise, the existing file will be overwritten with the current results.
Similar calculations can be performed on fully meshed models by using the Analysis Analysis
Weight and Center-of-Gravity command. See the page General Options: Weight and Center of Gravity Calculator.