Master Thesis - OUFTI-1

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However, in this conguration, a critical point that was not taken into account, is the saturation of the hysteretic bars by the permanent magnet. Indeed, this phenomenon limits the magnetic moment of the magnet, which presents a problem because this magnetic moment is essential to maintain the satellite attitude so, stronger it is, better is the solution. In accordance with these observations, the conguration with the greatest distance between the magnet and the hysteretic bars seems to be preferable. This situation is particularly tricky in nanosatellites because the available space is strongly restricted. Moreover, the principal axis of each hysteretic bar should be as close as possible of the plane perpendicular to the magnetization axis of the magnet. Any displacement from this plane leads to the apparition of an undesired component of the magnetic eld H magnet directed along the bar. This component results in a displacement of the working point on the hysteresis cycle, and it therefore aects the damping eciency of the hysteretic bar. An other problem is that the magnetic eld inside the hysteretic bars should be less than 30 A/m, which is a typical value of the Earth's magnetic eld on <strong>OUFTI</strong>-1 orbit. This suggests that the bars should ideally be placed as depicted in Figure 2.12. Figure 2.12: Ideal positioning of the hysteretic bars First conguration Firstly, it was decided to place the magnet on the battery support, close to the center of face −X. Its orientation was chosen in accordance with the requirement of the Radio Frequency (RF) subsystem: "The magnetization axis of the magnet must be parallel to the antennas' plane". The hysteretic bars were then placed as far as possible from the permanent magnet. Unfortunately, this conguration has showed an important inuence of the magnet on the hysteretic bars, which reduces the damping eciency. Figure 2.13 shows the magnetic eld due to the magnet in the vicinity of the hysteretic materials. Therefore, a new conguration with a greater distance between hysteretic bars and the permanent magnet must be found. 29
Figure 2.13: Magnetic eld obtained in the hysteretic bars for the rst conguration [25] Second conguration Then, it was decided to shift the magnet and to place it in the corner between faces −X, +Y and +Z. This new arrangement ensures the lowest possible inuence of the magnet on the hysteretic bars (as shown in Figure 2.14). Figure 2.14: Magnetic eld obtained in the hysteretic bars for the second conguration [25] Final conguration The critical point of the elongation of the hysteretic bars was not studied yet, and it appeared that it was crucial to have a high elongation. So, in order to satisfy this necessity, a new design was imagined. This one considers the possibility of using two parallel bars in each direction perpendicular to the magnet, for a total of four bars placed on corners between faces +X/ + Y , +X/ − Y , +Y/ − Z and −Y/ − Z respectively. So, to obtain the greatest distance between the magnet and the hysteretic bars, this one is placed in the middle of the corner between faces −X and +Y (as shown in Figure 2.15). 30
Page 1 and 2: University of Liège Faculty of App
Page 3 and 4: Abstract OUFTI-1, standing for "Orb
Page 5 and 6: 3.4 Initial idea . . . . . . . . .
Page 7 and 8: List of Figures 1.1 The Pumpkin's C
Page 9 and 10: 4.18 MAC matrix using the simple me
Page 11 and 12: List of Acronyms ADCS Al AlNiCo ASI
Page 13 and 14: Thesis outline This thesis focuses
Page 15 and 16: of larger satellites. So, the CubeS
Page 17 and 18: 1.2 OUFTI-1 project 1.2.1 Genesis O
Page 19 and 20: • XatCobeo (Vigo - Spain): Develo
Page 21 and 22: Chapter 2 OUFTI-1: Flight system co
Page 23 and 24: Figure 2.2: Product tree of OUFTI-1
Page 25 and 26: 2.3.2 Solar panels The armor panels
Page 27 and 28: • We do not want to drill or manu
Page 29: In our case, because of the limited
Page 33 and 34: Figure 2.17: Pictures of the ADCS c
Page 35 and 36: consider the possibility of oshorin
Page 37 and 38: Figure 2.20: Exploded view of OUFTI
Page 39 and 40: I xx , I yy and I zz are called the
Page 41 and 42: Subsystem: Structure & Conguration
Page 43 and 44: Subsystem: Thermal Control Parts Co
Page 45 and 46: Chapter 3 Design of a new support f
Page 47 and 48: 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
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• Global mass/stiness smearing me
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4.2.6 Modeling of the chassis A gen
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Q = ω k = 1 ω b − ω a 2 ζ ⇒
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Their study was based on the fact t
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Figure 4.14: Example of spacecraft
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Figure 4.15: Location of measuremen
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Figure 4.18: MAC matrix using the s
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4.3.6 Application of the local mass
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ρ P C 104 connector = 10.12 × 10
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According to this particular shape,
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This is due to the fact that this c
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environment. Then, this model is ex
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5.2.4 Antenna support For the anten
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Components Young's moduli (GP a) Po
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Components Young's moduli (GP a) Po
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5.3 Static analysis As described in
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Figure 5.9: Illustration of the com
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Figure 5.11: Maximal Von Mises stre
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Figure 5.12: First mode of OUFTI-1
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Figure 5.15: Precise PSD of Vega [5
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Chapter 6 Conclusions This master t
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provided for each method used. We h
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last versions of the Verication Con
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[13] Ph. LEDENT. "Design and Implem
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[40] "Dejond - Aluminum Catalog ".
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Appendix A Schemas of solar panels
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Appendix B Schemas of electronic ca
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Appendix C Fixations of the endless
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Appendix D Datasheet of the battery
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Master Thesis - OUFTI-1

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