Analyses On Dynamic Behaviors Of Ferromagnetic Beam-Plate Under Applied Magnetic Filed

In engineering practice, the electromagnetic apparatus and devices (i.e. the first wall structure of fusion rector, superconductive coils carrying with current, work pieces electromagnetic forming) will subject to the magnetic force when they located in magnetic field environment, when the magnetic intensity exceed one critical numerical value, the electromagnetic apparatus will generate plastic, and which will affect the electromagnetic apparatus' security. Hence it is very important and essential to study the characteristic of the elastic-plastic dynamic responses and the dynamic stability when the ferromagnetic beam-plate under the magnetic filed.In this dissertation, the magneto-elastic-plastic dynamic governing equations of ferromagnetic beam-plate with unmovable simple supports are derived at first, applying the perturbation technique get the magnetic force expression of the ferromagnetic beam-plate under the magnetic filed, then combine plastic knowledge, based on the sandwich beam model for elastic-plastic analyses and Gerlerkin's method, numerical computation the dynamic responses of ferromagnetic beam-plate. The frequency and equilibrium position of dynamic responses of the ferromagnetic beam-plate varying with the magnetic filed incident angle are given quantitatively, and the ferromagnetic beam-plate will deform plastic under the strong pulse magnetic filed, study the dynamic stability area et. The results indicate: the second mode will important and effect the ferromagnetic beam-plate' deformation as same as the first mode when the ferromagnetic beam-plate under oblique magnetic filed; the dynamic instability is strongly dependent on the amplitude, the shape and the duration of the pulse field. The critical magnetic field of pulse magnetic with rectangular shape is smallest; corresponding, that with sinusoidal shape is largest; In contrast the linear strain-harden elastic-plastic material ferromagnetic beam-plate is more stable and more hard deform plastic than the perfectly elastic-plastic material ferromagnetic beam-plate under the magnetic filed, and this mechanics characteristic will more obvious with increasing of plastic-strain harden coefficient of material. Finally, the residual configuration of the ferromagnetic beam-plate after the pulse magnetic filed is ended is presented in the dissertation.