Preload relaxation analysis and reliable life prediction of space connection and separation device based on accelerated degradation tests

The safety and reliability of space connection and separation device has become a key issue due to the increasing service span of deep space exploration mission. The long-term preload relaxation (a key failure mode) of connection and separation devices is focused in this paper. A series of tests have been designed and implemented to investigate the preload relaxation regulation and a comprehensive method has been constructed to analyze and predict the reliable lifetime of the device. The two-stage preload relaxation law of the device is found and reasonably considered. Due to the different relaxation mechanism, the first-stage preload relaxation is assessed based on the working-condition test results, and the second-stage preload relaxation is characterized by accelerated test results. Finally, the service reliability and reliable life are evaluated. The experiment and assessment results demonstrate the reasonability and effectiveness of the proposed method which can achieve long-service reliability analysis for space connection and separation device within limited time.