Strength Analysis - Finite Element Analysis for Satellite Structures - page 89

4.3 Model Development

A 3-D model of each structural module of Small Sat is created by means of
Mechanical Desktop package (MDT). Then an assembly model is formed for the
whole satellite structure without adding any satellite equipment. The assembled
model consists of the base plate, mounting plate, basis unit block, upper frame,
lower frame, battery bracket, star sensor bracket, and launch vehicle adapter.
Figure 4.2 shows the 3-D model of Small Sat structure used in the strength
analysis process.
Structural modules are transferred to ANSYS package using ''SAT'' format
without simplifying their topology. According to the complexity of structural
details of each module, the model of the satellite is divided into virtual (nonsu-
perelement) and superelement parts. The virtual parts are created through the use
pass phase to complete the whole satellite structure model in ANSYS. The
superelement parts of the model are divided into seven modules:

1. Base plate with four connection bushes
2. Mounting plate
3. Basis plate with two diagonal struts and star sensor bracket
4. Basis walls
5. Upper frame with battery bracket
6. Lower frame
7. Launch vehicle adapter

4.4 Material Model Behavior

The materials of the satellite structural modules are assumed to behave in the elastic
region. Therefore, linear isotropic behavior is used. Structural modules are made
of aluminum alloy AMg6 (E = 7.2 9 10 3 MPa, m = 0.33, q = 2630 kg/m 3 ,
r y ¼ 150 MPa ; r u ¼ 310 MPa Þ; while the connection elements (bushes, bolts, studs
… etc.) are made of steel (E = 20.7 9 10 3 MPa, m = 0.33, q = 7650 kg/m 3 ,

r y ¼ 620 MPa ; r u ¼ 862 MPa Þ:

4.5 Modeling of Equipments

Each satellite's equipment is fixed in its specific location with connation elements
(bolts or studs). Most equipment are connected at three or four fixation points.
Only rotation mechanisms and locking and releasing devices are fixed at two
points each. For modeling simplicity, rotation mechanisms, locking and releasing
devices, and solar panels are modeled as localized masses attached to their