Satellite Structural Design - Finite Element Analysis for Satellite Structures - page 51

square cross-section. This configuration provides the main load path and mini-
mizes the inherent complications of integration. The dimensions of the preliminary
configuration are represented in Chap. 2 . The rectangular configuration with a
square load path allows selection of a simple separation system between the
satellite and LV adapter.
The next step requires a selection of the basic primary structural design. By
reviewing the four basic designs discussed in the literature review and the pre-
liminary configuration presented in Chap. 2 , a skin-frame structure is found to be
the appropriate type used to design the basic primary structure of Small Sat. This
type is chosen because it has a heritage in small satellite structures. The design
enables deployed-fixed solar panels and allows mounting the satellite's components
to internal and external surfaces of its structural modules (plates and frames). The
next step in the design process is to prepare a technological breakdown scheme for
Small Sat. This scheme presents a total view for the satellite assembly and its
subassemblies. Figure 3.1 shows the satellite technological breakdown scheme.
3.3.1 Used Materials
The next step in the design process is to select the optimum material for the
primary structure. A large number of materials with space heritage are available
for satellite structural design and are presented in the literature review. Solid
metallic, honeycomb sandwich, and fiber composite are the three kinds of mate-
rials suitable for primary structure design. To select the best kind of material, each
of these materials is evaluated in more detail based on several design criteria. The
design criteria selected for the material selection are mass; design, development,
and test cost; ease of fabrication and assembly; ease of inspection and repair;
availability of material; and thermal performance. The evaluation clearly dem-
onstrates that metallic materials are the most effective in structural design for
Small Sat. There are several reasons for this decision. Fiber composite structures
are expensive to manufacture and require costly structural testing. Honeycomb
sandwich materials require potted inserts to attach fasteners, which create safety
concerns and parasitic mass. The metallic materials are relatively simple to
manufacture and minimize the safety and testing requirements.
The next step in the design process is to develop an optimum metallic material
for structural design. Several metals are used in satellite fabrication, such as
aluminum, titanium, beryllium, and stainless steel, which are discussed in detail in
Chap. 2 . These materials vary in cost, manufacturing time, mass, strength, and
durability. Aluminum alloy AMg6 is selected as the main material to manufacture
the primary structural modules for several reasons. The alloy is relatively abundant
and economically feasible for a low budget program. It has a density of approx-
imately 2,630 kg/m 3 , which is roughly one-third the density of steel with slightly
inferior strength. AMg6 alloy is used to manufacture and weld constructions
working at temperatures from -196 to +150 C. Finally, AMg6 is simple to