eta/DYNAFORM
refers to the local coordinate system to translate, rotate, mirror, copy, and
generate points, lines, or nodes. When such a function is selected, the program
will automatically prompt the user to generate a local system designated as the
UVW coordinate frame. The LCS dialog box illustrated in Figure 2.5.1 will be displayed. The user can create a new LCS or select a
system as the current LCS by clicking Global, Current LCS, Last Defined LCS, or
View Direction.
GLOBAL
Define the global coordinate system as the current LCS.
CURRENT LCS
Create a local coordinate system as the current LCS.
LAST
Define the last coordinate system as the current LCS.
VIEW
DIRECTION
Define the view direction as the W-Axis of the current LCS. The user can select or define a point as the origin, or the origin of the global coordinate system can be the origin of the current LCS.
There are two ways to create a LCS based on whether the Defined by 3 Locations toggle is checked.
1.
CHECKED (ON)
The user can select one, two, or three points/nodes to create a system. To select a node, choose Near Node. To select points, choose Near Point.
Figure 2.5.1 LCS dialog box
·
ONE POINT
Select a point and choose OK. The created LCS has an origin at the selected point and is a translation to the origin of the global system.
·
TWO POINTS
Select two points and choose OK. The first point is the origin. The W-Axis is the vector from the first point to the second point. The LCS is a translation and a rotation from X to U of the global system.
·
THREE POINTS
Select three points P1, P2, and P3. The point, P1, is the origin. The vector, P1-P2, is the U-Axis. The cross product of U and the vector, P2-P3, is the W-Axis. The V-Axis is determined by the cross product of W x U.
2.
UNCHECKED (OFF)
Define Origin, U-Axis, V-Axis, and W-Axis will be activated. To create a system in this case, the user needs to define an origin and axis. The LCS system will be a translation and a rotation of the global system.
·
Select Define Origin and the Input Coordinate dialog will appear. Select
a point or node as the origin, and then select OK.
·
Select one of the Axis buttons to define the axis in the LCS dialog.
·
Select By Point or Along Axis from the U/V/W-Axis dialog (Figure
·
Select OK from the Axis dialog.
·
Select OK from the LCS dialog.
·
The defined LCS is displayed.
Note: If the local coordinate system is not acceptable, use the No button to reject and redefine the coordinate system.
Figure 2.5.2 Define W-Axis