Master Thesis - OUFTI-1
Master Thesis - OUFTI-1 Master Thesis - OUFTI-1
located at the extremity of the considered endless screw, and the other (2) is situated at the same level, but in front of the hole of the chassis which allows to connect this one with the considered midplane stando. Then, the screw which realizes the connection between the chassis and the considered midplane stando, is modeled using the same method that for the connection between the base and end plates, and the chassis (by using two vertex (2 and 3), xed rigidly one to the other). Figure 5.6: Modeling of the midplane standos 5.2.7 ADCS and THER components The ADCS components, including the permanent magnet and the four hysteretic bars, are not modeled. The same decision was taken for the THER components, including heaters, thermostats and thermal insulation. This choice was made for several reasons: • First, due to their restricted dimensions and mass, they do not play a signicant role in the global behavior of the satellite. • In addition, they are all made of materials which present special properties so, these ones are dicult to obtain. • Finally, even if these properties can be obtained, they will be modify during the manufacturing of these elements (in the case of the permanent magnet and hysteretic bars) and so, the results obtained with and without these components, will not be more accurate one compared to the other. Now that the modeling of each part of the satellite is dened, the analysis can start. 109
5.3 Static analysis As described in reference [57], Vega, and so, its payloads, is subjected to quasi-static loads during ight. So, the aim of this study is to ensure the structural integrity of each part of the satellite when it is submitted to these steady state acceleration. 5.3.1 Loads denition The rst step is to clearly dene the quasi-static loads which will be applied on our CubeSat. For this, the worst case will be considered. This particular case occures if OUFTI-1 is placed in third position inside the P-POD because, in this conguration, it has to support the weight of two CubeSats in addition of the quasi-static loads imposed by the launcher. This conguration is illustrated in Figure 5.7. As remind, the P-POD will be placed at an angle of 10 ◦ from the vertical. Figure 5.7: Illustration of the worst case conguration The maximal steady state acceleration given in reference [57], is the one along the launcher's longitudinal axis. This acceleration has a value of 6.3 g. In our case, it was decided to apply a SF of 2 on each acceleration. So, the acceleration along the Z axis of the Vega frame is 12.6 g. The lateral accelerations, due to the dynamic pressure inside the launcher, have a maximal value of 1.2 g. So, an acceleration of 2.4 g will be applied along X and Y axes of the Vega frame. However, due to the particular conguration of the P-POD, a rotation matrix must be applied to these accelerations to bring them back in the CubeSat frame (as illustrated in Figure 5.8). Note that the CubeSat are placed with their base plate (face −Z) on the side +Z inside the P-POD (as it can be seen in Figure 5.8). This conguration is the one given in the ocial documents [58]. 110
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located at the extremity of the considered endless screw, and the other (2) is situated at<br />
the same level, but in front of the hole of the chassis which allows to connect this one with<br />
the considered midplane stando. Then, the screw which realizes the connection between<br />
the chassis and the considered midplane stando, is modeled using the same method that<br />
for the connection between the base and end plates, and the chassis (by using two vertex<br />
(2 and 3), xed rigidly one to the other).<br />
Figure 5.6: Modeling of the midplane standos<br />
5.2.7 ADCS and THER components<br />
The ADCS components, including the permanent magnet and the four hysteretic bars,<br />
are not modeled. The same decision was taken for the THER components, including<br />
heaters, thermostats and thermal insulation. This choice was made for several reasons:<br />
• First, due to their restricted dimensions and mass, they do not play a signicant role<br />
in the global behavior of the satellite.<br />
• In addition, they are all made of materials which present special properties so, these<br />
ones are dicult to obtain.<br />
• Finally, even if these properties can be obtained, they will be modify during the<br />
manufacturing of these elements (in the case of the permanent magnet and hysteretic<br />
bars) and so, the results obtained with and without these components, will not be<br />
more accurate one compared to the other.<br />
Now that the modeling of each part of the satellite is dened, the analysis can start.<br />
109
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