| Popis: |
In space hardware development projects, reliability is at the forefront because of environmental conditions, radiation effects and maintenance difficulty. However, low reliability equipment fails and causes satellite loss before completing service life. To eliminate this problem, analyses such as reliability prediction, derating, worst case, Failure Modes, Effects and Criticality Analysis (FMECA), at development phase are conducted according to European Space Standardization Cooperation guidance documents. FMECA guided in ECSS-Q-ST-30-02C is the most comprehensive reliability analyses in which potential failures are identified and evaluated. The aim of this study is to introduce a new hybrid FMECA approach by presenting a case study on Power Control Unit (PCU) which is mission critical satellite equipment. PCU performs battery charge/discharge processes and provides power to satellite equipment by conditioning energy from solar panels. If failure modes in FMECA aren't determined in detail and probability of occurrence isn't calculated precisely, satellite mission can be lost. Hence, equipment's electronic boards are divided into hardware blocks and their functions determine failure modes. Failure rates taken from reliability prediction analysis are distributed to electronic boards and small hardware blocks respectively, thus failure modes' probabilities could be calculated more precisely. Consequently failure modes are analyzed; criticalities are evaluated by performing hybrid FMECA for PCU electronic boards. Hereby, all possible failure modes are examined and their criticality is correctly determined, and possibility of satellite loss result from equipment failure is minimized. |
