Separation Characteristics Of A Large-scale Payload Fairing With Consideration Of The Manufacturing Tolerances

Rocket is a tool that can be used to send payloads,such as satellites and space station,to a predetermined location.With the increase of level of science and technology in China,the rocket is designed larger and larger.The payload fairing,as rocket's separation system,determines whether the payload could be brought into the predetermined orbit by the launch vehicle successfully.Therefore,robustness of separation characteristics is the key issue for design and manufacturing of launch vehicles.Due to the manufacturing tolerances which will affect the stability of the separation characteristic of a large-scale payload fairing,it is necessary to examine its influence level.As the internal structure of the payload fairing is very complex,a higher demand of analytical efficiency leads to requirement of a suitable model for calculation.Therefore,it is of great practical significance to simplify the model of payload fairing and study on the separation characteristics of manufacturing tolerance based on such simplified model.The main contents of this paper are shown as follows:(1)Simplified models of the fairing is proposed from the original precise finite element model of it.Comparing with the original precise finite element model,it is found that the efficiency of computation is improved by using the simplified ones greatly while the separation characteristics of them are ensured similar to those of the original one.(2)The effect of different distributions of springs' positions on the separation characteristics of fairing is studied.It is found that there is the same effect of different distributions of springs' positions on the separation characteristics in the rigid model,but not in the elastic model.If springs in the elastic model are near the longitudinal separation surface,there are greater elastic vibrations which result in large fluctuations to the separation characteristics of the fairing.(3)The analytical result of separation characteristic of the rigid fairing is derived as considering the deviation of the mass and the spring stiffness.Based on the analytical result,the sensitivity of the separation characteristics of the fairing is obtained to the influence factors.Then the factor that had a great influence on the separation characteristics of the fairing is picked up.It is shown that the mass deviation of the front cone and the deviation of the spring stiffness have a great influence on the separation characteristics of the fairing.(4)The characteristics of the fairing when the centroid of payload fairing reaches the highest point were analyzed by using the simplified elastic model of the fairing under three different factors,such as mass deviation,spring failure and the distribution of mass point.It is shown in such elastic model that the mass deviation of the front cone and the failure of single spring will lead to a great influence on the characteristic of fairing when the centroid of payload fairing reaches the highest point.It is also shown that relationship among the mass of each section,angular velocity and time as fairing over top is linear.In the elastic model of the fairing,effects of the distribution of different regions of the mass point are different on the elastic vibration and the characteristics of the fairing when the centroid of payload fairing reaches the highest point.A region with little influence on the separation characteristics and elastic vibration of the fairing is given here.