Strength Analysis - Finite Element Analysis for Satellite Structures - page 194

Fig. 4.81 Angular positioning deviation between two equipments [ 7 ]

The modified angle between normal vectors to the deformed mounting plane is
calculated as:

0
@

1
A

* 0
nA

* 0
nB

h 0 ¼ cos 1

* 0
nA

* 0
nB

The angular positioning deviation angle between equipment A and B is cal-
culated by:

h dev ¼ h 0 h
For Small Sat, the angular positioning deviation angle h dev (arcmin) is calcu-
lated for the precise equipment mounted on the basis unit block relative to the star
sensor. Table 4.30 lists the values of the angular positioning deviation angles due
to on-orbit thermal deformation relative to the star sensor. It shows the results for
both maximum and minimum on-orbit temperatures. By comparing these results
with the limiting values listed in Table 4.29 , it is found that the performance of the
satellite is not significantly affected by on-orbit thermal deformation under max-
imum or minimum temperatures.

4.16 Fatigue Damage Calculation Due to On-Orbit Thermal
Cyclic Loading

One of the most important results of on-orbit thermal deformation analysis is to
evaluate the fatigue damage due to on-orbit cyclic thermal stresses. The ductile
material (AMg6 aluminum alloy) used to manufacture the satellite structure
modules does not rupture or buckle from a single application of thermal stress,