Reliability Evaluation of Secondary Power Module under Aerothermodynamic Comprehensive Effect

Abstract

During the re-entry of the spacecraft, it will encounter severe environmental effects such as aerodynamic heating and multi-degree-of-freedom vibration, which brings challenges to the reliability assurance of the secondary power module installed in the bulkhead. In this paper, the transient thermal shock and three-axis six-degree-of-freedom vibration conditions applied to the secondary power module are obtained based on the measured aerothermodynamics data from the flight and the thermal transfer model from the outside to the inside of the spacecraft bulkhead. Next, a finite element model of the secondary power module is established and the thermal transfer characteristics of the model are verified through thermal equilibrium tests and modal tests. Then, simulation analysis is performed under transient thermal shock, three-axis six-degree- of-freedom vibration, and transient thermal shock + three-axis six-degree-of-freedom vibration. The key components with the largest stress-strain response are identified. In addition, the failure modes and mechanisms of the comprehensive thermal effects of the key components are analyzed and the CalcePWA reliability simulation based on the failure mechanism is carried out, from which the physical laws of the failure of the key components are obtained. The thermal environmental effects and failure modes of the secondary power module during the ground development, launch, and orbit flight reveal that the failure mode of the relay's contact resistance increases during the reentry process will become more severe. The ground test optimization and design improvements can ensure the task reliability during reentry.