Satellite Structural Design - Finite Element Analysis for Satellite Structures - page 54

ensure acceptable structural through stiffness and mass properties. The next steps
determine if the manufacturing cost and schedule of the structure are acceptable.
The final steps in the design process examine the assembly, manufacturing, and
operational aspects of the design. Many steps are taken to easy handling, assembly,
and manufacturing issues throughout the process. Finite element analysis tech-
niques are coupled with development considerations to arrive at the most efficient
design. Upon successful completion of the design process, the final Small Sat
structural design is obtained.

3.4 Preliminary Analysis

To size the preliminary design of the structure, a simplified static analysis is per-
formed on the primary structure modules. An iterative procedure as described in
Sect. 3.3.3 is used. The initial structural design for milled plates and modified
isogrid frame structures is chosen according to the preliminary configuration
described in Chap. 2 . The initial structural design is established to provide appro-
priate mechanical interface between structural modules, and follow the arrangement
of components installed on each structural module. Using the mechanical loading
conditions described in Appendix A, finite element analyses for each of the struc-
tural modules are performed to arrive at the most efficient design.

3.4.1 Strength Analysis Cases

By reviewing the various mechanical loads described in Appendix A, the most
critical quasi-static loads lead to two strength analysis cases:
Case 1: The satellite loading by operational g-loads during road transportation
in the container. Table A.1 gives the operational g-load factors as:

n x ¼ 2 ; n y ¼ 1 : 25 ; n z ¼ 1 2 :

where: ''±'' is attached to the dynamic components, and ''1'' for n z g-load is the
loading caused by weight. The X-axis of vehicle is in the forward-motion direc-
tion, the Z-axis is vertically down, and the Y-axis makes the system right-handed.
Case 2: The satellite loading by maximum longitudinal and lateral g-loads
during launch. From the operational g-loads given in Table A.8, the combinations
of the maximum axial ''n a '' and lateral ''n l '' g-load factors during the first and
second LV stages flight are found to be:

n a ¼ 7 : 8 0 : 5 ; n l ¼ 0 : 1 0 : 5