Figure 4.3: An Unbalanced Rotating Antenna
Plan
2 1
3 4
Frameof
Reference
Ωt
Elevation
W
Rotating
antenna
4 - pointsupport
Ω
(FrameofReference)
FZ =Fcos(Ωt- 45 °)
FZ=Fcos(Ωt- 135 °)
(FZ 3 andFZ 4 omittedforclarity)
An unbalanced rotating antenna will produce out-of-phase vertical loads at its four
support points.
Note
A harmonic analysis cannot calculate the response to multiple forcing functions acting sim-
ultaneously with different frequencies (for example, two machines with different rotating
speeds running at the same time). However, POST1 can superimpose multiple load cases to
obtain the total response.
Table 4.2: Applicable Loads in a Harmonic Analysis (p. 83) summarizes the loads applicable to a harmonic
analysis. Except for inertia loads, you can define loads either on the solid model (keypoints, lines, and
areas) or on the finite element model (nodes and elements). For a general discussion of solid-model
loads versus finite element loads, see Loading in the Basic Analysis Guide.
Table 4.2: Applicable Loads in a Harmonic Analysis
Cmd GUI Path
Family
Load Type Category
Main Menu> Solution> Define Loads> Ap-
ply> Structural> Displacement
Displacement (UX, Constraints D
UY, UZ, ROTX, ROTY,
ROTZ)
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Performing a Harmonic Analysis