Small sample reliability evaluation method of ion thruster on the basis of performance degradation

Abstract

The invention discloses a small sample reliability evaluation method of an ion thruster on the basis of performance degradation. The small sample reliability evaluation method comprises the following steps: 1: analyzing the structure characteristics and the key failure mode of the ion thruster, and selecting a key performance parameter which affects the service life of the ion thruster; 2: according to the degradation law of a key performance parameter y along with time, establishing a performance degradation model of the small sample of the ion thruster; 3: determining the average failure time tMTTF (Mean Time To Failures) and the reliability function R(t) of the ion thruster; 4: for an ith ion thruster, recording a test performance degradation value yij at time tij, wherein i is equal to 1,2...m, j is equal to 1,2...ni, m is the number of the ion thrusters which are put into an experiment, and ni is the total frequency of the performance test of the ith ion thruster; 5: establishing unknown parameters in the performance degradation model; and 6: utilizing a reliability function to carry out small sample reliability evaluation on the ion thruster. The sample reliability evaluation method develops and utilizes longitudinal information among different pieces of performance test data at different moments, an amount of information is greatly increased, analysis accuracy is improved, and a great quantity of specimens can be saved under the situation of the same accuracy.

Description

【Technical field】 [0001] The invention relates to a reliability analysis method for a very small sample of an ion thruster based on performance degradation, in particular to a reliability analysis method for a single-unit life test of an ion thruster with no failure in the test data. It belongs to the technical field of aerospace reliability analysis. 【Background technique】 [0002] Electric propulsion is one of the top ten cutting-edge technologies in the future. Compared with traditional chemical thrusters, it has the characteristics of high specific impulse, high efficiency, long life, and low thrust. It can be used to perform space missions such as north-south position protection, orbit improvement and deep space exploration. The ion thruster is a kind of electric propulsion, because its thrust is relatively small, which requires a long time to run to meet the requirements of the total impulse. Therefore, as long-life equipment, ion thrusters are generally required to ...

AI Technical Summary

Problems solved by technology

The characteristics of long life and high reliability of the ion thruster bring certain difficulties to its reliability analysis

[0005] Due to the high manufacturing cost of the ion thruster and the restriction of the test conditions, the life test can only be performed on a single machine each time, resulting in limited reliability test samples, which belong to the category of extremely small samples; at the same time, affected by the tight development cycle, the life test It is often impossible to carry out for a long time, and the test results are mostly no failure data

In addition, because the research on electric propulsion technology is not yet mature enough, and the acceleration factor that affects its life is not yet clear, it is impossible to conduct accelerated life tests on it

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