Abstract: At the takeoff time of the 0-0 launch abort test for Mengzhou manned spacecraft, multiple key processes are parallel. The potential fault modes of the key processes are coupled with each other, resulting in complex fault mechanisms and unclear mechanical responses. By analyzing the mechanical behavior of each fault mode at the takeoff time of the test, the takeoff safety of the 0-0 abort test is evaluated.The research is mainly conducted through theoretical analysis and numerical simulation. According to the force conditions of the escape system under different fault modes, the theoretical formula for the local maximum load of the escape system is derived. At the same time, finite element analysis and dynamic analysis are combined to confirm the theoretical results. Based on the mechanical analysis results, whether the escape system under different fault modes has the structual damage, whether it owns escape capabillity, as well as the impact on the trajectory after escape are given. Finally, the takeoff safety is evaluated through margin analysis.Through mechanical analysis, there are four fault modes, the safety margin of which is greater than 0.7 during the takeoff of the 0-0 launch abort test. Only one fault mode has no safety margin and it is classified as a medium level risk.Through a systematic study on the takeoff safety of the 0-0 launch abort test of Mengzhou manned spacecraft, a set of mechanical analysis method for the escape system is proposed: a theoretical model for the axial load of the cabin pyrotechnic lock is established; the methods of finite element analysis and dynamic analysis for each fault mode are proposed;the key mechanical characteristics that affect the safety of the escape system are identified. The research method in this paper can be extended to the takeoff safety analysis of the escape tests or launch missions for similar spacecraft.

Key words: Mengzhou manned spacecraft, 0-0 launch abort test, takeoff safety, finite element, dynamics