The Research Of Damage In Bore And Rail Deformation Of Electromagnetic Launcher

When the electromagnetic launcher(EML)accelerates the armature,the rail is in harsh conditions of high temperature,high pressure and high speed sliding electric contact due to a powerful current.And the rail is vulnerable to be damage and deformation,which affect the life of rails,accuracy and efficiency.It is significant to study the deformation and damage mechanism of rails,which is beneficial to the design of EML insulation structure.This paper summarizes the mechanisms of groove,arc erosion and gouging based on the related literature on the rail damage,and analyzes the characteristics of all these damages,such as distribution,shape,depth,length and other physical parameters.The rail of EML is simplified as the elastic foundation beam model.Based on numerical calculation results of deflection for the elastic foundation beam model,we get the rail's deflection quantitative relationship with the armature's time and position,and the results are analyzed.In addition,aiming at the shortcomings of measuring methods of rail current and armature's displacement,this paper proposes an improved method based on the current waveform and B-dot probes,and a test validation is done.A bore dimension measuring device based on programmable logic device and image sensor is designed to do an engineering verification for theoretical analysis and simulation calculation of the rail deformation and damage.And it makes up for the deficiency of EML bore diagnosis methods.The hardware and software framework of the device is given.The software and hardware debugging and testing are completed.The rail will bear transient and powerful electromagnetic force on a large scale.The improved measuring method of armature velocity and rail current based on current waveform and B-dot probe has more practical physical meaning.The armature velocity is more accurate,and velocity information can be obtained at any time.The amplitude of rail deformation is closely related to the amplitude of current.The amplitude of deformation shows a process of oscillation attenuation as the power wave propagates forward.The area in front of the armature is not affected by electromagnetic force,and the contact points between armature and rails,are affected by the transient electromagnetic force.The breech deformation is much larger than the muzzle deformation due to the impact of current's action time and current amplitude of the EML.The deformation of rails will have the cumulative effect after repeated launch,so the insulation strength of breech should be stronger than muzzle.The preload of insulation at different positions on the rail should match the corresponding stress.