Study On Mechanical Properties Of Quasi-isotropic Superconducting Strands Stacked By REBCO Tapes And Copper Tapes

With the research on superconducting materials,the second generation of REBCO high-temperature superconducting tapes appeared,and superconducting power transmission technology has entered a stage of rapid development.However,the REBCO tape has the problems of anisotropy and small transmission capacity,which has become a factor restricting the development of superconducting power transmission technology.In order to solve these two problems,a variety of superconducting strand structures have appeared in the world.These superconducting strands are composed of REBCO tapes stacked together in different ways.Quasi-isotropic superconducting strands,as one of them,can exhibit better isotropy and higher current density.In order to improve the economy of superconducting power transmission and increase the utilization rate of superconducting tape,this paper proposes two new superconducting strand structures by introducing copper tapes into superconducting strands.These two kinds of superconducting strands are quasi-isotropic superconducting strands stacked REBCO tapes and copper tapes alternately,and stacked REBCO tapes outside and copper tapes inside.A two-dimensional(2 D)steady-state simulation model of quasi-isotropic superconducting strands stacked by REBCO tapes and copper tapes was established,and the critical current of the superconducting strands was simulated;samples of the superconducting strand were made and the critical current was tested.According to the built model,the critical current characteristics of two kinds of superconducting strands stacked with different thicknesses of copper tape and different stacking methods are simulated,on this basis,the quasi-dimension of stacking REBCO tapes on the copper former is proposed.This superconducting strands can also be twisted to further increase the engineering current density and reduce the AC loss.For the study of the mechanical properties of quasi-isotropic superconducting strands,firstly,the tensile,bending and twisting properties of REBCO tapes were tested through specific experimental molds.At the same time,the bending and twisting characteristics of quasi-isotropic superconducting strands stacked REBCO tapes and copper tapes alternately were tested.Then,a method for studying the mechanical characteristics of quasi-isotropic superconducting strands based on the laminate theory is proposed,and a three-dimensional(3 D)finite element simulation model was established,and the relationship between current density and stress of quasi-isotropic superconducting strands was proposed.The critical bending radius of the quasi-isotropic superconducting strand is calculated.Finally,through the built model,the critical bending radius of the quasi-isotropic superconducting strands when bent in different directions was simulated.The study found that the anisotropy rate was less than 18%.