Design and development of inter-satellite separation mechanism for Twin Nano satellite — STUDSAT-2
This paper describes the detailed design, development and dynamic analysis of Separation Mechanism for Twin Nano-satellite “STUDSAT-2”. The separation mechanism system is interfaced between the two nano-satellites, STUDSAT-2A and STUDSAT-2B. After the ejection from the PSLV (Polar Satellite Launch Vehicle), due to stability constraints, the satellite is required to remain composite for an estimated period of 3 orbits before separation. Developing a reliable separation mechanism to sustain the launch vehicle vibrations and the space environment is of highest importance. Different design approaches and actuation strategies have been examined to ensure a uniform separation with least disturbance due to mechanically constrained surfaces. The analytical calculation to achieve the required relative velocity of the two satellite with respect to center of mass of the composite structure is performed and same has been validated using ANSYS rigid dynamics tool. Furthermore, the tool is also used to validate structural rigidity.
Failure analysis of deployment mechanism of a satellite solar array
The reliability issue of a solar array deployment mechanism was analyzed with FMECA and FTA. The main failure modes, their effects and criticalities were illustrated. A fault tree was built. Both qualitative analysis and the quantitative analysis of the fault tree were performed. The probability of the top event, the structural importance and the critical importance coefficients of different basic events were calculated. According to the analyses, the main reasons of the satellite solar array deployment mechanism failure and the list of the critical components were presented, and the effects of different failures were classified according to the severity and the criticality of the faults. Recommendations for improving solar arrays' reliability were provided for reliability design and structure improvement of the satellite solar array deployment mechanism.
Numerical tools applied to power reactor noise analysis
In order to be able to calculate the space- and frequency-dependent neutron noise in real inhomogeneous systems in two-group theory, a code was developed for the calculation of the Green's function (dynamic transfer function) of such systems. This paper reports on the development as well as the test and application of the numerical tools employed. The code that was developed yields the space-dependence of the fluctuations of the neutron flux induced by fluctuating properties of the medium in the two-group diffusion approximation and in a two-dimensional representation of heterogeneous systems, for both critical systems and non-critical systems with an external source. Some applications of these tools to power reactor noise analysis are then described, including the unfolding of the parameters of the noise source from the induced neutron noise, measured at a few discrete locations throughout the core. Other concrete applications concern the study of the space-dependence of the Decay Ratio in Boiling Water Reactors, the noise-based estimation of the Moderator Temperature Coefficient of reactivity in Pressurized Water Reactors, the modeling of the beam- and shell-mode core-barrel vibrations in Pressurized Water Reactors, and the investigation of the validity of the point-kinetic approximation in subcritical systems driven by an external source. In most of these applications, calculations performed using the code are compared with at-power plant measurements. Power reactor noise analysis applications of the above type, i.e. core monitoring without disturbing plant operation, is of particular interest in the framework of the extensive program of power uprates worldwide.