Strength Analysis - Finite Element Analysis for Satellite Structures - page 130

6

5

4

3

2

1

0

0 50 100 150 200 250 300 350

Frequancy (Hz)

Fig. 4.43 Sinusoidal vibrations for the three mutually perpendicular directions during air

transportation

1.2

1

0.8

0.6

0.4

0.2

0

1 10 100

Frequancy (Hz)
Axial

Fig. 4.44 Axial and lateral sinusoidal vibrations during flight of the launch vehicle

A 2 A 1
log ð f 2 Þ log ð f 1 Þ

A ð f Þ¼ ð log ð f Þ log ð f 1 Þ Þ þ A 1

5. Where: f 1 & f 2 are the lower and upper values of the frequency band, respec-
tively in (Hz), and A 1 & A 2 are the corresponding accelerations in (g).
6. Table 4.10 shows the vibration-acceleration amplitude at the first 15 sorted
natural frequencies of the satellite structure for all dynamic loading phases.
Vibrations in each phase act simultaneously, and are generated from the same
source, that is why they affect the satellite structure in all directions in the same
time. Displacement boundary conditions are the DOF constraints usually
specified at model boundaries to define rigid support points. The same
boundary conditions applied for the satellite during static and modal analyses
are reapplied for harmonic response analysis.