Separation system is one of the most important systems in rockets. The influence of this system on mission success cannot be ignored. In this paper, reliability of a sounding rocket separation system is determined using block diagram and FMEA . This system is based on the flexible linear shape charge cross-section and a spring mechanism to accelerate separation. In this investigation, the reliability block diagram of the separation system including mechanical and electrical mechanisms is determined. By considering reliability of each component based on expert opinion and using separation system reliability block diagram, reliability of separation system is determined. Moreover, since spring mechanism is one of the most important parts of separation system, a complete FMEA analysis is conducted for this mechanism. According to this analysis, piston, cylinder, pin, and springs have the highest RPN number. Hence, these parts must have a high reliability. On the other hand, results are shown that bracket and bush have the lowest RPN number; therefore, it is not important for these parts to have a high reliability.


[1] Hessari, B.B. and Yap, D.F.W., The Victoria Satellite-Feasibility Study and Communication Protocol,  (M.Sc. Thesis), The Royal Institute of Technology (KTH), Stockholm, 2002.
[2] Singaravelu, J., Jayakumar, D. and Rao, B.N., “Taguchi's Approach for Reliability and Safety Assessments in the Stage Separation Process of a Multistage Launch Vehicle,” Journal of Reliability Engineering and System Safety, Vol.10, No. 94, 2009, pp. 1526-1541.
[3] Gorgin, R., Farsi, M.A. and Kalantari-Nezhad, R. and Ebrahimi, M., “Reliability Determination of a Sounding Rocket Separation System Using Monte Carlo Simulation,” The Proceeding of 2011 International Conference on Quality, Reliability, Risk, Maintenance, and Safety Engineering, Xian, China, 2011.
[4] Modarres, M., Kaminskiy, M. and Krivtsov, V., Reliability Engineering and Risk Analysis, Marcel Decker Inc, 1999, p. 198.
[5] Modarres, M., Kaminskiy, M. and Krivtsov, V.,  Reliability Engineering and Risk Analysis: A Practical Guide, CRC PressINC, 2010.
[6] Henning, S. and Paasch, R., “Diagnostic Analysis for Mechanical Systems,” The Proceedings of DETC'00 ASME 2000 Design Engineering Technical Conferences and Computers and Information in Engineering Conference Baltimore, Maryland, 2000.
[7] Wang, W. and Loman, J. M. “Reliability Block Diagram Simulation Techniques Applied to the IEEE Std. 493 Standard Network,” IEEE Transaction on Industry Applications, Vol. 40, No. 3, 2004, pp. 887-895.
[8] Stamatis, D. H., Failure Mode and Effect Analysis: FMEA from Theory to Execution, Second Edition, American Society for Quality, 2003.
[9] Birnbaum, L.W., On the Importance of Different Elements in a Multi Element System, Multivariate Analysis, Vol. 2, New York: Academic Press, 1969.
[10] Fussell, J. B., How to Calculate System Reliability and Safety Characteristics, IEEE Trans Reliab, R-24, Vol.3, 1975, pp.169–74.