# Simulation Analysis and Experimental Verification of the
###### Abstract  
The Microgravity Platform (MP) of the Chinese Space Station is locked and released by Lock-or-Release (L/R) mechanism on both sides. In order to ensure the safety and reliability of the MP under the vibration environment during the rocket launch, the L/R mechanism must output the appropriate locking torque value. Based on the structural characteristics of the Scientific Experiment Cabinet (SEC), this paper proposes a method of evaluating locking torque by combining theory with experiment, and the relationship between locking force and locking torque of L/R mechanism is proved that the locking force on both sides can reach 2000 N at 25 Nm driving torque. Finally, it is verified by vibration test that the locking torque obtained by this method can effectively guarantee the safety and reliability of the MP under vibration environment.  
microgravity platform; lock-or-release mechanism; Chinese space station; vibration test updates [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] Simulation Analysis and Experimental Verification of the Locking Torque of the Microgravity Platform of the Chinese Space Station. _Appl. Sci._**2021**, _11_, 102. [[https://dx.doi.org/10.3390/app11010102](https://dx.doi.org/10.3390/app11010102)]([https://dx.doi.org/10.3390/app11010102](https://dx.doi.org/10.3390/app11010102))  
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The MP is a cuboid test device located in the middle part of the MSHML, which is fixed by the L/R mechanism during the launch. When it arrives at the predetermined orbit of the space station, the L/R mechanism on both sides is driven in reverse at the same time to release the MP for scientific research [10,11]. For the special locking requirements of the MP, the locking force directly affects the locking reliability of the MP. In the process of launching into orbit, the MSHML will experience a variety of mechanical environments, including vibration, impact, noise, constant acceleration, etc. [12]. When resonance occurs in the MSHML, if the locking torque supplied by the L/R mechanism on both sides is insufficient, relative displacement may occur between the L/R mechanism and the MP, which may cause relative slippage between the thread of the locking device, and even cause incomplete contact between the MP and the lead screws of the L/R mechanism on both sides. The MSHML cannot form symmetrical and regular pretension deformation, and it may cause rich and complex nonlinear vibration phenomena of the platform, such as frequency doubling, frequency division, bifurcation, chaos during the rocket launch [13]. With the continuous action of vibration load, intensive dynamic response will occur, which may lead to the collapse or work performance degradation of the MSHML. It also poses a threat to personnel and rocket, and the damage in orbit is not easy to repair. On the other hand if the locking force is too large, excessive pretension will be generated inside the MSHML, which causes excessive predeformation of the structure, and due to the excessive load, poor lubrication, and other harsh operating conditions, faults may occur in the gear systems of the L/R mechanism [14]. Keeping this state for a long time will also have a significant impact on the cabinet, even permanent deformation. In order to ensure the high reliability and safety of the MP in the rocket launching environment, it is very important to evaluate the reasonable locking torque.  
Aiming at this special problem, this paper designs a method to evaluate the locking torque based on the characteristics of the MSHML. Through theoretical analysis, numerical simulation, experiment, and other aspects, the reliability of the L/R mechanism is analyzed to obtain the locking torque that meets the vibration environment.