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___________________________________________________ UDC 519. Technical mechanics, 2024, 2, 66 - 75 DETERMINATION OF OPTIMAL SPACECRAFT RELIABILITY NORMS WITH ACCOUNT FOR ECONOMIC INDEXES Savonik O. M.
Savonik O. M.
The goal of this paper is to develop a method for determining the values of system failure rates optimal in
terms of net profit maximization with account for spacecraft mass limitations. It is adopted that the
spacecraft systems are independent in terms of reliability, each of them can be only in two states (a
functioning state or a failure state), and each equipment type of the special complex makes an independent
contribution to the overall effect. The paper considers the case where the spacecraft system failure time
obeys the exponential law. Use is made of the Lagrange multiplier method and numerical optimization methods.
The problem is solved using the mass ? failure rate and cost ? failure rate relationships of the spacecraft
systems. For the supporting complex, the dimension of the mathematical simulation problem is reduced to two:
a formula is derived to find the optimal failure rates of all the systems of the supporting complex using
the optimal failure rates of two systems of it. The variables for the special complex and the supporting
complex are separated. Due to the fact that each special complex system makes an independent contribution to
the overall effect, the problem for the whole spacecraft is reduced to a system of two equations for the
special complex and the supporting complex and ncn equations in one variable for the special complex with two
coupling variables between the supporting complex and the special complex where ncn is the number of the
special complex systems. The paper presents a numerical-and-analytical method for spacecraft system failure
rate optimization where the initial guess is specified indirectly: by specifying the supporting complex mass
and probability of no-failure operation. The method may be used in the development of a space hardware design
methodology accounting for economic factors. From the optimal values of the spacecraft system failure rates
found using the mass ? failure rate and cost ? failure rate relationships, one can find the masses and costs
of the spacecraft systems to be used in optimizing the parameters and development cost of the systems. The
method is expected to increase the profitability and competitiveness of spacecraft under development.
optimal reliability norms, spacecraft, profit, cost, design
1. Linnik A. K., Baldin A. A. Formulation of a cost engineering problem. Systemne Proetuvannya ta Analiz Kharakterystiks Aerokosmichnoi Tekhniky. 2013. V. 15. Pp. 58-62. (in Russian).
Copyright (©) 2024 Savonik O. M. Copyright © 2014-2024 Technical mechanics ____________________________________________________________________________________________________________________________ |
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