Reliability Modeling And Analysis Of Solar Array Drive Assembly In Satellite

As an exchange channel of energy and signal between satellite interior and solarwings, SADA (Solar Array Drive Assembly) is one of the key devices in satellite. It isthe power source of satellite and it fundamentally affects the reliability and lifetime ofsatellite. In all faults of satellite, the frequency of solar wings is the most according tostatistics. About40%of the failures of SADA are due to mechanical reasons, mainlyfailure of deployment and solar wing structure. Electronic failure of SADA is mainlydue to short circuit of internal drive circuit. With the development of space technology,SADA is becoming more complex with various functions, and it changes from singledegree of freedom to two degrees and two axes.It has prominent difficulty analzing the reliability of SADA when considering outerspace. First, there is difficulty in data collecting, because research object is often smallsample or even single sample. Secondly, many random factors in space result incomplex failure modes. Again, the limitations of experiment funds and technology leadthe difficulty of ground-based simulation, which means many parameters areunpredictable and uncertain. So far, there is not much research on reliability of SADA indomestic and overseas except for some books and literatures introducing its principleand structure. So it’s meaningful to carry out reliability modeling and analysis of SADAand this thesis attempts to analyze the reliability of SADA with several methods.1. Firstly, the structure and working principle of SADA are introduced in this thesis,and then the complex environment features in outer space and their effects on SADA issummarized according to the research in domestic and overseas.2. A FMEA sheet is concluded on the basis of analyzing failure mechanism inspace environment. Failure modes analysis on key components such as stepper motorand harmonic gear is summarized. At last, according to the “Guide to failure mode,effects and criticality analysis”, a FMEA sheet is generated.3. Reliability model of SADA is established respectively from RBD (ReliabilityBlock Diagram) and Petri net model. On the basis of SADA’s function flow chart, blockdiagrams of task reliability and basic reliability can be built. Petri net model owns dynamic and structural properties, which means it’s more effective than traditionalmodeling method in system analysis. When modeling a Petri net, first we shouldconsider the structure and redundancy of the component, and then regard the state ofcomponent as place, the weakness as token, the failure as transition, the cause of thefailure as excitation condition. Finally through describing the transiton of bottomcomponents and the logical relationship between all levels, Petri net model of SADA isestablished.4. Markov chain and BDD (Binary Decision Diagram) is repectively used toanalyze dynamic subtree and static subtree after DFT (Dynamic Fault Tree) of SADA isbuilt. On the basis of getting minimum cut set of subtree and probability of top event,we finally get minimum cut set and probability of the integrated DFT of SADA.5. Rational ALT(Accelerated Life Test) of SADA is designed in this thesis. It isdifficult to verify the life indicators of aerospace products’ vital components. Usually,accelerated life test is adopted to speculate characteristic parameters under normal stressin order to shorten test time and cost. The object of accelerated life test in this thesis issolid-lubricated and low-speed rolling bearing which is properly installed on SADA.The acceleration factor is turn speed and we should convert the actual cumulative turnsinto working years in orbit. By analyzing failure data, we can determine whether therolling bearing satisfies the requirements of life.