VIEW XSECTION Mode [Definition of Plane]

          

FEMVIEW Command only.

This command enables the user to view a plane cross-section through 3-dimensional elements. The cross-section plane may either be defined as part of the command or one or more previously defined plane(s) may be referenced.

Mode Definition of Plane

/CURSOR The cursor is used twice to define a section plane that lies normal to the plane of the screen.

NODES The user enters the numbers of three nodes that lie in the section plane.

OLD The most recently viewed cross-section is re-displayed.

shape_name(s) The named shape(s), which must be planes, are selected and the corresponding cross-section(s) are viewed simultaneously. Also, a global plane may be specified at different offset positions and the corresponding cross-sections viewed simultaneously. (See note 1).

Notes:

1.

Viewing multiple cross-sections using previously defined shapes
Multiple cross-sections may be viewed simultaneously by specifying up to 20 shape names in the command. These shapes, which must be planes, must have been previously defined with the CONSTRUCT SHAPE PLANE command. Also, multiple cross-sections may be viewed by referencing a shape that is a plane defined in one of the model global planes and specifying the number of times the plane is to be repeated and the distance between repeats. Hidden views of multiple cross-sections can be obtained via the VIEW HIDDEN command, however, note that the software algorithms provided for hidden views do not work reliably with polygons that intersect each other which is a condition that could occur with multiple cross-sections.

2.

Limitations on use
It is not advisable to attempt to define a cross section in the plane of a plane external surface of a model by specifying three nodes on that surface with the `VIEW XSECTION NODES' command. This is because the intersection algorithm slightly perturbs the plane of intersection towards the centroid of the current subset of elements in order to prevent the plane passing `exactly' through the specified nodes. If a cross section is defined on an external surface this perturbation may cause the plane of intersection to move away from (outside of) the surface of the model. Either the `VIEW XSECTION /CURSOR' command should be used to cut a section just inside the surface or the surface should be isolated by the `VIEW FACES' command.

 

Figure 2.136: Cross section

Examples:

1.

VIEW XSECTION /CURSOR

Displays the cross section defined by the plane containing the points identified by the cursor.

2.

VIEW XSECTION NODES 23 46 85

Displays the cross section defined by the plane containing nodes 23, 46 and 85.

3.

VIEW XSECTION OLD

The most recently viewed cross-section is re-displayed.

4.

VIEW XSECTION Sh1 Slice Slice1 Flange

The plane shapes `Sh1', `Slice', `Slice1' and `Flange' are used to specify four cross-sections to be viewed simultaneously.

5.

VIEW XSECTION Refsec REPEAT 4 OFFSET 5.0

The plane shape `Refsec', which must be normal to one of the global axes, is used to specify five cross-sections to be viewed simultaneously. The positions of the sections will be the original position of `Refsec' and at offsets 5.0, 10.0. 15.0 and 20.0 along the global axes from `Refsec'.

See also the following commands

'CONSTRUCT SHAPE PLANE'
'EYE NORMAL'
'VIEW CUTAWAY'