Satellite Structural Design - Finite Element Analysis for Satellite Structures - page 55

The following values of safety factors are adapted from Appendix A:

• During road transportation in the container ''case 1''

- f = 1.5—for static g-load component
- f = 2.0—for dynamic g-load component

• During the flight phase of launch ''case 2''

- f = 1.3

Hence, the critical limit loads for Small Sat are as follows:
Case 1:
N x = 2 9 2 9 9.81 = 39.24 m/s 2
N y = 1.25 9 2 9 9.81 = 24.53 m/s 2
N z max = (1 9 1.5 ? 2 9 2) 9 9.81 = 53.96 m/s 2
N z min = (1 9 1.5-2 9 2) 9 9.81 = -24.53 m/s 2
where

N x is the lateral ''shear'' acceleration in the forward-motion direction,
N y is the lateral ''shear'' acceleration in the Y-axis,
N z max is the maximum axial ''longitudinal'' acceleration in the Z-axis
N z min is the minimum axial ''longitudinal'' acceleration in the Z-axis
The resultant (equivalent) shear acceleration is:

q

ð N x Þ 2 þð N y Þ 2

m = s 2 N I ¼ ¼ 46 : 28

Case 2:
N a = (7.8 ? 0.5) 9 1.3 9 9.81 = 105.85 m/s 2
N l = (0.1 ? 0.5) 9 1.3 9 9.81 = 7.64 m/s 2
where N a is the axial ''longitudinal'' acceleration, and
N l is the lateral ''shear'' acceleration.

3.4.2 Design of Fastening Studs and Small Sat/LV
Interface Bolts

From the conceptual configuration of Small Sat described in Chap. 2 , the satellite
structure consists of a base plate, upper frame, basis unit, lower frame, and
mounting plate. These structural modules must be fastened together to work as a
load path to provide structural requirements. The most effective method to provide
acceptable mounting accuracy and alignment is using fastening studs connecting
structural modules in the satellite case subassembly. The connection between Small
Sat and launch vehicle adapter or transportation container is done through interface
bolts. The holes of these bolts are installed on specified locations in the base plate.