Structural Buckling Of Pulsed Magnets In Ultra-high Field

Ultra-high field pulsed magnets are operating under extreme conditions such as high voltage,high current and high stress,which will cause magnet explosion accidents and great economic losses.However,the existing failure model is focus on the material strength model and ignored the structure instability problems,and it is difficult to explain the phenomenon that the ultra-high field pulsed magnet is often damaged below the design value.This restricts the development of pulsed high magnetic field technology.Previous studies have shown that buckling is one important reason for the failure of pulsed magnets,but the mechanism and evolution law of buckling in pulsed magnets are not clear.In this paper,the buckling behavior of the free-standing layer is studied by FEA models and experiments.In order to study the buckling mechanism of pulse magnets in depth,this paper equates the free separation layer of pulse magnets to thin-walled cylindrical shells.Starting from the buckling theory of cylindrical thin-walled shells,the static buckling behavior and dynamics of the free separation layer structure of pulsed magnets are developed.Simulation analysis of buckling behavior and related experimental tests have been carried out.Firstly,the basic concept and content of structural buckling analysis are described.Then,the linear buckling behavior of cylindrical shells with different geometric dimensions and materials is analyzed by combining the linear buckling theory of cylindrical shells and FEA method.In the aspect of static electromagnetic buckling research,the ANSYS finite element model of static electromagnetic buckling of pulsed magnet is established,and the effects of geometric size,spiral structure and load distribution on the static buckling behavior of single winding layer are analyzed.Furthermore,LS-DYNA FEA models of dynamic buckling are also established to consider the impact load.Combined with the stress wave effect and inertia effect,the effects of pulse width,geometric size and material parameters on the dynamic buckling of single winding layer were analyzed.Finally,based on the static / dynamic FEA buckling models,three kinds of single-layer coils are developed,and the electromagnetic buckling experiments are carried out.The experimental results show that the buckling problem indeed exists in the pulse magnet,and the experiment results of the buckling are consistent with the simulation results,which verifies the electromagnetic buckling models established in this paper.