Research On Cumulative Damage Failure Of Driving Coil In Coil Launcher

The electromagnetic coil launcher has been widespread concern in the military andaerospace fields for its high emission efficiency and high launching speed with heavyobjects. Driving coil and its encapsulation are key components in coilgun that can bedestoryed for five or six launching times due to the huge electromagnetic force. In order todesign a coilgun meet the service performance required, research on its cumulative failureis significant.This paper mainly talks about driving coil and coil encapsulation in single-stagesynchronous induction coilgun. The stress distribution in coilgun is solved by circuit-magnetic-structure coupling analysis. In this paper, we proposed a data transfer methodbetween nonmatching meshes. Moreover, this method was used in coupled electromagneticfluid-dynamic and thermal analysis of the object mentioned in the reference. Thecomparison of calculation results with experiment results in reference proves feasibilityand correctness of this method.On this basis, failure mechanism and fatigue life areresearched combining working status and stress-life curve of the coilgun. The results showthat the maximum stress in coil encapsulation is higher than the ultimate tensile strength,some regions are destroyed. In the subsequent launching process, damaged area graduallyexpanded until the encapsulation is destoryed completely. The maximum stress in coil issmaller than its yield strength, but fatigue fracture emerged caused by launching for anumber of times.With the improving of the material of the encapsulation, stress distribution in drivingand its encapsulation are all in permissble range, the fatigue life of driving is prolonged.Through the observation of microstructure of the fracture, the cumulative injury fatiguemechanisms of the coil are analyzed. The research method of this paper can be used as thedesign guide and surplus value assessment for coil launcher. The research result is valuableto engineering application.