Master Thesis - OUFTI-1

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5.4 Modal analysis This analysis will allow to predict the global dynamic behavior of OUFTI-1. In this analysis, the CubeSat is modeled using exactly the same strategy as in section 5.2. Only the static loads and the boundary conditions are removed to obtain the behavior of OUFTI-1 in "free-free" boundary conditions. This type of study allows to obtain a rst idea of its behavior in real life conditions in a simple way. In addition, the results can be used to realize a model updating. Indeed, this conguration has the advantage that it does not introduce additional unknowns about the boundary conditions. So, the model updating can be performed more accurately. However, these conditions are really dicult to simulate during an experimental test and some approximations must be done (but it is not the topic that we want to develop here). 5.4.1 Results It was decided to compute the ve rst modes of OUFTI-1. Their natural frequencies are listed in Table 5.8. Modes (mm) Natural frequencies (Hz) 1 325.51 2 333.92 3 343.27 4 368.63 5 377.29 Table 5.8: Five rst natural frequencies of OUFTI-1 in hard-mounted conguration It can be noted that all these frequencies turn around a value of 350 Hz. This is due to the fact that each of these modes excites only the electronic cards of OUFTI-1 (and their xations). These results prove that OUFTI-1 respects the ESA requirement on the natural frequencies: "The Cubesats shall not have structural modes at frequencies lower than 120 Hz in hard-mounted conguration". Now, the rst two modes will be described (the following ones present the same behavior and so, it does not have a great interest to analyze them): • The rst mode of OUFTI-1, which corresponds to a natural frequency of 325.51 Hz, is presented in Figure 5.12. 115
Figure 5.12: First mode of OUFTI-1 (325.51 Hz) This mode is characterized by a vibration, in phase opposition, of the two extreme electronic cards (the FM 430 on the side −Z and the COM on the side +Z). The other electronic cards, the main structure and the external panels are not excited by this mode. • The second mode of OUFTI-1, which corresponds to a natural frequency of 333.92 Hz, is presented in Figure 5.13. Figure 5.13: Second mode of OUFTI-1 (333.92 Hz) This mode is characterized by a vibration of most electronic cards. Indeed, the FM 430 and the COM present oscillations in phase, just like the EPS and xEPS. These two groups of cards vibrate in phase opposition one from each other. It can also be seen that the endless screws are more involved in this mode than in the rst one. The OBC 2 card, the main structure and the external panels are not excited by this mode. 116
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University of Liège Faculty of App
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Abstract OUFTI-1, standing for "Orb
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3.4 Initial idea . . . . . . . . .
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List of Figures 1.1 The Pumpkin's C
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4.18 MAC matrix using the simple me
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List of Acronyms ADCS Al AlNiCo ASI
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Thesis outline This thesis focuses
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of larger satellites. So, the CubeS
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1.2 OUFTI-1 project 1.2.1 Genesis O
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• XatCobeo (Vigo - Spain): Develo
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Chapter 2 OUFTI-1: Flight system co
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Figure 2.2: Product tree of OUFTI-1
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2.3.2 Solar panels The armor panels
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• We do not want to drill or manu
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In our case, because of the limited
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Figure 2.13: Magnetic eld obtained
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Figure 2.17: Pictures of the ADCS c
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consider the possibility of oshorin
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Figure 2.20: Exploded view of OUFTI
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I xx , I yy and I zz are called the
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Subsystem: Structure & Conguration
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Subsystem: Thermal Control Parts Co
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Chapter 3 Design of a new support f
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Figure 3.3: Batteries during and af
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The concept is the following one: F
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A test under vacuum conditions was
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Thermal Expansion (CTE) of the mate
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Figure 3.9: Classication by density
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The last property to determine is t
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• So, it was decided to use two t
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is to prevent the batteries' bulge.
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• Then, the thermostats, that wil
Page 65 and 66: Figure 3.23: Schematics of the cove
Page 67 and 68: • Other components, including the
Page 69 and 70: 3.9.3 Dynamic behavior Finally, it
Page 71 and 72: 3.10 Summary Through this chapter,
Page 73 and 74: Chapter 4 Electronic cards dynamic
Page 75 and 76: Figure 4.1: Example of manufacturin
Page 77 and 78: Figure 4.4: Illustration of the exp
Page 79 and 80: Figure 4.5: MAC between the two mod
Page 81 and 82: • Global mass/stiness smearing me
Page 83 and 84: 4.2.6 Modeling of the chassis A gen
Page 85 and 86: Q = ω k = 1 ω b − ω a 2 ζ ⇒
Page 87 and 88: Their study was based on the fact t
Page 89 and 90: Figure 4.14: Example of spacecraft
Page 91 and 92: Figure 4.15: Location of measuremen
Page 93 and 94: Figure 4.18: MAC matrix using the s
Page 95 and 96: 4.3.6 Application of the local mass
Page 97 and 98: ρ P C 104 connector = 10.12 × 10
Page 99 and 100: According to this particular shape,
Page 101 and 102: This is due to the fact that this c
Page 103 and 104: environment. Then, this model is ex
Page 105 and 106: 5.2.4 Antenna support For the anten
Page 107 and 108: Components Young's moduli (GP a) Po
Page 109 and 110: Components Young's moduli (GP a) Po
Page 111 and 112: 5.3 Static analysis As described in
Page 113 and 114: Figure 5.9: Illustration of the com
Page 115: Figure 5.11: Maximal Von Mises stre
Page 119 and 120: Figure 5.15: Precise PSD of Vega [5
Page 121 and 122: Chapter 6 Conclusions This master t
Page 123 and 124: provided for each method used. We h
Page 125 and 126: last versions of the Verication Con
Page 127 and 128: [13] Ph. LEDENT. "Design and Implem
Page 129 and 130: [40] "Dejond - Aluminum Catalog ".
Page 131 and 132: Appendix A Schemas of solar panels
Page 133 and 134: Appendix B Schemas of electronic ca
Page 135 and 136: Appendix C Fixations of the endless
Page 137 and 138: Appendix D Datasheet of the battery
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Master Thesis - OUFTI-1

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