VT Analysis and Testing Document:
Structural Component Qualification

Authors

Craig Stevens

Last Updated:10/24/2001

Document Number:AA-21301-DOC001-1

Revision Number: 1

Virginia Tech

Department of Aerospace & Ocean Engineering

Blacksburg, VA 24060

Revision / Desription / Author / Date / Approval
1 / Requirements
Component List / Craig Stevens / 10/24/01 / pending
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Table of Contents

Revision History...... 1

Table of Contents...... 2

1Introduction3

2structural REquirements3

3component structural qualification4

1Introduction

This document outlines the analysis and testing required to verify the structural integrity of the Virginia Tech "HokieSat". All components within the spacecraft are required to be qualified for the launch environment at Virginia Tech. Component qualification is essential to ensure that all failures are mitigated before any stack configuration testing.

2Structural Requirements

The structural requirements for component qualification are based on both NASA and AFRL structural requirements. The requirements are listed in detail in the MSDS Users Guide (MUG). A component is qualified by fulfilling the MUG requirements. A basic approach to qualifying a component analytically is described below.

  • Perform an acceptable structural analysis. The analysis should account for the mounting configuration and load paths, as well as the hardware survivability. The analysis depends on several variables, but it may range from a "worst-case" theoretical calculation to a complex finite element analysis.
  • Calculate the Margin of Safety (MS) using the following equation:

where the Actual Stress is the maximum stress computed in the analysis. The Allowable Stress is either the ultimate stress or yield stress of the material, which can be found in MIL-HDBK-5D Metallic Materials and Elements for Aerospace Vehicle Structures. The factor of safety (FS) is determined based on the following variables in Table 1.

Table 1 - Factors of Safety for Ultimate / Limit Loads

Test & Analysis / Analysis Only
Factor of safety for limit load (onset of yield) / 1.25 / 2.0
Factor of safety for ultimate load / 1.4 / 2.6

The component design satisfies the loading requirements if the margin of safety is greater than or equal to zero.

The component also may be qualified for launch using structural testing. Any type of static or dynamic testing that fulfills the requirements in the MUG is acceptable. Please seek approval for the testing from Craig Stevens before performing any structural tests on flight hardware.

Note: The assembled spacecraft testing at NASA Wallops Flight Facility (WFF) may be used as qualification.

Proper vibration protection is also required to receive component qualification. All interfaces must have some type of vibration or backout protection to prevent loosening during the high-frequency dynamic environment. The protection should adhere to the plan stated in the HokieSat Back-Out Protection Procedure. The protection method must be verified either at WFF or another random-vibration test procedure.

3Component Structural Qualification

Structural testing and/or analysis should be performed on every flight hardware component in HokieSat. A procedure must be made by the responsible engineer to qualify a component for launch on the spacecraft. Table 2 describes the testing and analysis plan for each component.

Table 2 - Component structural qualification plans

Component / Analysis / Testing / REA
Structural Assembly / I-DEAS FEM / Wallops / Craig Stevens
Solar Cells
Science Patches
X/L Antenna Assy
U/L Antenna Assy
D/L Antenna Assy
GPS Antenna Assy
Magnetometer Assy
Aux Port Cover
Nadir Sun Sensor
Camera Assy
Gyro Assy
Torque Coil Assy
X/L-GPS Hardware / APL / APL / APL
U/L Rx
D/L Tx
Batt Box
CEE
PPT Assy
PPU
Connectors
Wiring
1 WB Assy
Integration Brackets

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