Master Thesis - OUFTI-1

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Thanks to these results, the following conclusions can be drawn: • The increase of mass brought by the sensor has an important eect on the value of the natural frequencies. Indeed, it can be seen that, even with a sensor of 0.2 g, the shift in frequency reaches a value of 13.87 Hz, which is not negligible. And this eect becomes more important when the mass of the sensor increases. This problem is essentially due to the fact that the studied structure has very restricted dimensions and mass. So, any increase of mass, so small it is, involves interferences with the PCB dynamic response. • This eect can also be highlighted with the mode shape. Indeed, it can be seen that the amplitude of the PCB deformation at the sensor location decreases when the mass of the sensor increases. So, in this particular case, it will be better to use a sensor which does not need to touch the structure to perform the measurements (e.g., laser transducers, ...). This allows to avoid any interference with the dynamic response of this structure. Modeling of the P C 104 connector The second analysis concerns the modeling of the P C 104 connector. It was choose to represent it using a detailed FE model, for reasons exposed previously. But, the question is: what does this particular choice involve on the PCB dynamic response To answer to this question, the fourth mode of the OBC 2 card for the two dierent type of modeling, is shown in Figure 4.24. Figure 4.24: Inuence of a change of modeling strategy for the P C 104 connector on the OBC 2 card's fourth mode Thanks to these results, it can be seen that the inuence of the P C 104 connector on the PCB dynamic response is stronger using the detailed FE model (the deformation of the card is less important at the connector location and more important on the opposite side). 99
This is due to the fact that this connector brings a non-negligible increase of stiness to the PCB, and that this particular increase is not taken into account using the local mass smearing method. So, the best solution is well to use the detailed FE model for the P C 104 connector. 4.4 Summary Through this chapter, the electronic cards dynamic modeling was discussed. First, we took a turn of the several existing methods to realize this particular modeling. The accuracy of each method was studied and the critical parameters on which this accuracy is mainly dependent, were highlighted. Then, these methods were applied to the homemade OBC of <strong>OUFTI</strong>-1. The results obtained were correlated with ones measured during an experimental test. Finally, some sensitivity analysis were undertaken to study the eect of several parameters on the dynamic behavior of the OBC 2. After this chapter, the following conclusions have to be kept in mind: • The most accurate method developed in this chapter is the homemade method, which combines several general methods to create an accurate FE model of the electronic card. So, it is this method that will be applied in the following chapter. • The experimental results could be better. So, if an other test is performed next year, the following facts have to be taken into account: To come closer to the "free-free" boundary conditions, the card could be xed by only one hole, using one elastic. The set-up will be more unstable, but the additional modes that will be excited, are rigid body modes so, there is no problem. The hammer excitation is the best solution to excite the structure in "free-free" boundary conditions. However, it could be better to realize the test using a stainless steel tip, which will bring a stronger PSD. Note that it will need to bring attention to the "bounce" eect. It could be interesting to give up the "free-free" boundary conditions and to realize a chassis which allows to x the electronic card on a shaker. Thus, the real boundary conditions of the electronic card's lifetime will be more accurately reproduced and the results will be better. Note that the chassis have so to be included in the FE model. 100
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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
Page 49 and 50: The concept is the following one: F
Page 51 and 52: A test under vacuum conditions was
Page 53 and 54: Thermal Expansion (CTE) of the mate
Page 55 and 56: Figure 3.9: Classication by density
Page 57 and 58: The last property to determine is t
Page 59 and 60: • So, it was decided to use two t
Page 61 and 62: is to prevent the batteries' bulge.
Page 63 and 64: • 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: According to this particular shape,
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 and 116: Figure 5.11: Maximal Von Mises stre
Page 117 and 118: Figure 5.12: First mode of OUFTI-1
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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