(Quoc Huy Vu1, Phu Khanh Nguyen1,2
1Department of Aeronautical and Space Engineering - Hanoi University of Science and Technology
2Center for Development and Application of Software for Industry - Hanoi University of Science and Technology)

F-1 nanosatellite having a mass of 2 kg with dimension of 10x10x22 (cm) is developed to satisfy the mission of imaging Vietnam surface and data transfer service. Satellite structure contains 5 main components (as shown in the Figure 1): solar panel, skin, frame, printed circuit board and antenna. During the satellite lifetime, two phases have a great influence on the structural durability including launching period and orbital period. Two important issues, hence, rise respectively on the mechanical structural analysis during launching period and on the thermal structural analysis as well as orbital period. This paper deals with the problem of mechanical analysis during launch period.

The numerical analysis is carried out by using Finite Elements Method (FEM). In order to well represent the complex geometry of the nanosatellite, an unstructured mesh is used with element sizing control. Figure 2 presents the detailed FE model for selected structure components. During launch period, the applied loads on the structure are considered in this study including:

  • Inertia loads contain gravity, upward inertial load with longitudinal acceleration of 7g and centripetal force with lateral acceleration of 2,5g.
  • Reserve force for pushing the satellite out of payload when the satellite is in orbit.
  • Dynamic random vibration loads during transportation and launch.

On the structural static analysis, the random vibration loads are considered equal to an upward inertial load with acceleration of 40g. It is considered to be a compensation coefficient of dynamic loads when computing safety factor. 3D Finite Element Analysis for the satellite structure allows observing stress distribution and deformation on every part of the satellite. It is shown that the satellite structure satisfies durability with a safety factor greater than 10.

Modal analysis is performed for F-1 structure to determine vibration characteristics of the satellite (natural frequencies and mode shapes). Resonance takes place when frequencies of vibration loadings (due to rocket launching) match one of the natural frequencies. According to source of PSLV rocket, the natural frequencies of the satellite must be greater than 40 Hz in the longitudinal axis and than 18 Hz in the lateral axis. For F-1 structure, the first natural frequency is found to be 204,3 Hz satisfying the frequency constraint. Ranking of mode shapes according to participation factor and effective mass is carried out. That allows identifying the most important mode which has the greatest contribution on the satellite response. The modal analysis also serves as a starting point for more detailed dynamic analysis such as harmonic response analysis or spectrum analysis in further works.

Figure 1. Main components of F-1 nanosatellite

Figure 2. 3D Finite Element model and meshing of the satellite

For more detail information, please refer to:
Quoc Huy Vu and Phu Khanh Nguyen. Structural and modal analysis for f-1 nanosatellite. Proceeding of the 5th Southeast Asian Technical University Consortium Symposium (SEATUC), paper 556 - 559, ISSN 1882-5796, 2011.