A Study On The Launching Stability Of Electromagnetic Railgun Using Solid-armature And The Law Of Initial Engraving Process

Up to now, there is no acknowledged and complete therotical model to describe the electromagnetic launching process at home and abroad. Try to implement high precision strike in long range, it is necessary to ensure the stability of launcher. The consistence of muzzle velocity of solid armature is applied to characterize the stability of launching system. Although there are many effectors influencing the stability of velocity of armature,the control of initial status is easy to realize at the present experimentl condition,for example, the enactment of values of charge voltage and indunctance, the adjustement of parameters of armature and the variation of initial pressure between armature and rails, and so on. Under the limitation of current experiment, the classical mathematical statistics method can not be adopted to analyze the electromagnetic launching experiment.Aiming at the problem of small sample and difficulty of therotical analysis, the grey system theory is appled in this dissertation where the small caliber electromagnetic railgun using solid armature is taken as the research object. Based on the analysis of experimental data, the preliminary study on the stability is carried on. The main contents are as follows:1. Electromagnetic launching experimental study has been carried out. The influencing law of the variation of different parameters under the simultaneous discharge has been analyzed by measuring charging current, muzzle voltage and breech voltage. The result of existing influencing factors during launching process is obtained by analysis the consistence of continuous experiment and comparison of lumped parameter model and experiment.2. The grey correlation analysis and grey model are adopted to do the research on factors influencing muzzle velocity of solid armature. On the basis of build the index system of factors affecting muzzle velocity of armature, the grey relation entropy method is applied to analyze the significance of factors influencing the scattering of armature’s muzzle velocity in lumped parameter random ballistic model and launching experiment. The results show that the main influencing factors are discharge voltage and capacitance, and the effect of armature’s mass is the smallest. And diameter of armature is the main influencing factors.Based on the grey analyzed model building and driving coefficient analyzing, the charge voltage is the most important promoting effect on improving muzzle. It is proposed that there is a certain inherent positive connection between weight coefficient of armature mass and armature transition.3. The different grey prediction models are established to carry out the research on the relation between the stability of launch system and parameters of solid-armature. The prediction of muzzle velocity is analyzed based on these models, and then, the analysis is carried out by combination with measured temperature and strain in order to obtain the law of muzzle velocity of armature with the armature diameter variation. The result shows that the initial magnitude of interference shrink range has great influence on the stability with the other parameters the same. The development of influencing factors of preliminary study is carried on based on multi-variable grey prediction model, which can provide the reference for adjustment of experimental parameters.4. In order to choose appropriate engraving mode and parameter of loading parameters, the research on the initial engraving process of solid armature in small caliber electromagnetic railgun is carried out. The three engraving modes including uniform loading, impact loading and combined loading are simulated by using finite element method, and then the change of radial deformation, stress and shear stress of elements in the armature arm are compared and analyzed. The results show that the combined loading can obviously decrease the degree of shearing damage during solid armature engraving process and, in addition, improve initial contact pressure effectively in the same condition. To further study the contact characteristics of contact-surface, simulation on interference fits of various magnitudes of armature, coefficients of friction and velocities of engraving process are performed and the distribution curves of contact pressure are obtained.Based on the research on the consistence of launching process and initial engraving process, some results with theorestical and engineering significance were obtained,which will be helpful to promote technical decelopment of consistence of electromagnetic railgun.