Master Thesis - OUFTI-1

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4.2.1 Accuracy of the model First and foremost, it is important to note that the accuracy of the FE model which will be created, is strongly related to the decision-making. Indeed, if the results required are the component internal stresses, a detailed FE model is necessary. However, the long time required to build and solve this type of model can not be justied when only the PCB response is required. In this case, it is possible to greatly simplify the model by using several methods which will be discussed later. In addition, the accuracy of a FE model will be mainly dependent on various sources of error, including: • Manufacturing variability, which will cause deviations in the vibration response of supposedly identical PCBs. This variability includes not only material and assembly properties, but also dimensional tolerances applied during the manufacturing procedure. • Inaccuracies in the denition of the model input parameters. They can result from the modeling assumptions used or the impossibility to obtain reliable values of these parameters (no prototype available, ...). • Errors in the solution process (e.g., linear solutions in non-linear situations). The major diculties encountered during the creation of a PCB FE model are so: • To specify the input parameters, namely: stiness, density, boundary conditions and damping. The accuracy with which these parameters are specied, will determine the accuracy of the predicted response. So, experimental tests must be performed to determine reliable values of these parameters in order to obtain an accurate FE model. • Variation of these parameters due to manufacturing, assembly, wear, ... An example of manufacturing variation is shown in Figure 4.1, where the same test is performed on supposedly identical PCBs. It can be directly seen than the responses obtained are really dierent one from the other. 73
Figure 4.1: Example of manufacturing variation [44] • Limitations due to parameters and variation sources which can not be easily specied, such as non-linear eects, limitations of the FE mesh, physical eects that are too complicated to be easily included in the model (i.e., air or acoustic inuences), ... Most often, these diculties are overcome by including appropriate SF in the model. 4.2.2 Creating FE models of PCBs The procedure to follow for creating FE models of PCBs, can be divided into 5 parts: • Determination of the PCB properties • Recognition of components eects • Modeling of the chassis • Denition of the boundary conditions • Introduction of damping 4.2.3 Determination of the PCB properties The PCB properties include: Young's modulus, Poisson ratio, density, thickness, ... The specication of these properties represents the most dicult step in creating a PCB FE model. In general, their values may be provided by manufacturers. However, these values are not always exact (as shown in Figure 4.2). So, it is better to determine them by ourselves. 74
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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
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 and 30: In our case, because of the limited
Page 31 and 32: Figure 2.13: Magnetic eld obtained
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: Chapter 4 Electronic cards dynamic
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 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
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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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