Modeling On Operation Process Of Low-shock Separation Device And Its Performace Research

Pyrotechnic device is the key part of the spacecraft. The performance of pyrotechnic device is the key to the fly mission success. However, the continued use of traditional pyrotechnic devices such as explosive bolt is questioned by the large impact and high cost. The low-shock separation device, whose separation impulse is lower than 2N?s, has a better joint strength and lower start-up energe than explosive bolt. Although the low-shock separation device is widely used in the fly mission, few introductions and researchs are published. In this paper, some researches on the low-shock separation device are reported.The separation process of the low-shock separation device is analyzed. Based on the aerodynamics and first law of thermodynamics, a mathematical model for the separation process of air-operated test is built. The pressure vibration in the separation device is simulated. The simulation results are consistent with the experimental results. The influences of structural parameters of separation device on the separation process are simulated. The influence of air supply pressure on the separation process is simulated, too.The low-shock separation device is usually driven by initiating explosive device. A model used to simulate the separation process of explosive test is built. With the same explosive charge, the influences of structural parameters of separation device on the separation process are simulated. The underlying case which may induce the failure of separation is explored. The simulation result is helpful to the optimization design of separation device.The low-shock separation device is used as the connecting device with the screw thread connection before the separation order is given. To ensure the connection reliability, the low-shock separation device needs to be tightened to a high preload level. Using the same pre-tightening torque, the preload is discrete. The influences of preload discreteness on the separation process (both air-operated test and explosive test) are simulated. The simulation results show that the preload discreteness may induce the peak pressure fluctuation and there is an upper limit for preload in the explosive test. If the preload exceeds the upper limit, the separation of explosive test fails in theory. To make sure and improve the reliability of low-shock separation device, it is necessary to make probability density estimation for the preload. The number of preload test result can not fulfill the requirement of the traditional probability density estimation method. The support vector machine (SVM) is selected to estimate the probability density of preload. To enhance the computational efficiency of SVM algorithm, an improved algorithm is proposed. Training the same samples, the improved algorithm shortens the train time while the precise of estimation is not changed. The estimation result of preload is consistent with the experimental reslut. The combined influences of bolt preload and structural parameters on the explosive test are simulated. It is shown from the results that the increased basal areas of separating ring can reduce the sensitivity of separation device for the bolt preload. This result is instructive for the reliability design of low-shock separation device.To verify the model for the separation process, the separation performance of low-shock separation device must be tested. The traditional separation test is inefficient and dangerous. A new measurement and control system for the separation test is developed in this paper. Using this system, the prload, peak pressure and separation impulse in the separation test can all be collected. The experiments verify the effectiveness of the model for the separation process.