Creo Simulate > Additional Information > Working With Normals > Specifying Y Direction for Beams
  
Specifying Y Direction for Beams
When you create a beam, Creo Simulate sets the beam length as the X axis of the beam action coordinate system. You determine how the beam action coordinate system relates to the WCS by specifying the Y direction on the Beam Definition dialog box. See Beam Coordinate Systems for more information.
If you reference two geometric entities such as two points, or a point and a surface, for the beam length, the positive X direction goes from the first entity selected to the second. If you reference an edge or curve, Creo Simulate displays a purple arrow pointing in the positive direction when you select the edge or curve. If you want to reverse the positive X direction, select the edge or curve again.
The illustration shows a beam with a square cross-section defined along a curve that is parallel, but opposite in sign to, the WCS X axis. The software uses the beam X axis and the Y direction you specify on the Beam Definition dialog box to define an XY plane for the beam action coordinate system. It then defines a Z axis perpendicular to the XY plane, and completes the coordinate system using the right-hand rule.
Creo Simulate displays an error message if the Y direction vector that you specify is not valid. The error message is displayed when you use one of the beam references for the vector direction or when the magnitude of the vector is zero. However, in both native and FEM mode, beams of zero length are allowed between pairs of point, that is, pairs that are in contact. In such a case, Creo Simulate checks the Y direction only when the value is zero.
Creo Simulate continues to create the beam but displays a warning message if the Y direction vector that is calculated is parallel to the axis of the beam or is zero in magnitude as in the following instances:
The vector that you specify in the WCS to define the Y direction is parallel to the axis of the beam.
The axis that you specify to define the Y direction is parallel to the axis of the beam.
The point that you specify to define the Y direction lies on the axis of the beam.
The tangent at the point evaluated on the Y direction curve is parallel to the axis of the beam.
A normal at the projected point from the axis of the beam to the surface of the Y direction is parallel to the axis of the beam.
In the FEM mode, the Y direction curve is evaluated at the beginning of the curve and Creo Simulate uses the tangent at this point on the curve as Y direction for the Y direction checks for beams. This is for beams that have Y-directions defined as point-surface and point-edge pairs and curves.
Return to Y Direction for Beams.