Investigation On The Damage Behavior Of High Temperature Superconducting Tape In CORC Cable

Because of their excellent electromagnetic properties,superconductors have been widely used in medical treatment,energy,transportation,national defense and other fields.The CORC cable(Conductor on Round Core)wound by second generation HTS tapes(REBCO)has high current-carrying capacity and outstanding mechanical properties.In the extreme service environment,REBCO tapes with layered composite structure are vulnerable to damage and even internal delamination when they are subjected to winding stress,thermal stress and electromagnetic force.After the damage inside the tapes occurs,the critical current of CORC cable will be affected,which will lead to the quench.Therefore,the study on the mechanical damage behavior of superconducting cable has important engineering application value,which can guide the design of the superconducting cable and promote the optimization of the whole superconducting device.In order to solve the above problems,we preliminarily simulate the mechanical response of CORC cable under external load in this dissertation,and discuss the local damage characteristics of the tape.The main contents of this dissertation are as follows:Firstly,in order to consider the influence of the stress in the tape after the manufacturing processes of the tape and the CORC cable on the damage behavior of the tape,the cooling,tension and spiral winding processes of second generation HTS tape(REBCO)are simulated respectively.Then,the distribution of the residual stress and strain during cooling,the stress distribution of the tape under tension,and the distribution of the strain in superconducting layer after winding are compared with the relevant results of the existing literature.The reliability of the finite element model in this dissertation is preliminarily verified.In addition,the influences of some parameters on the stress and strain in tape during the cooling,tension and spiral winding processes are analyzed.It is found that the compressive strain in the superconducting layer after cooling and winding is smaller,while the tensile stress in the superconducting layer after tension is larger when the substrate material is stainless steel.Next,we introduce the concept of CZM(Cohesive Zone Model)which can characterize the tape damage behavior,and then the constitutive relationship of CZM(Traction-Separation Law)is described.On this basis,a simplified model of the CORC cable is established,and the simulation results after winding are imported into the tape as initial condition.Then,we simulate the deformation processes of the CORC cable under external loads.Finally,the effects of different loading types(tension and bending of the CORC cable)and model parameters on the damage behavior of the tape are analyzed by comparing different simulation results.The results show that the bending deformation of the CORC cable is more likely to cause damage in the tape than the tensile deformation,and the damage degree of the tape increases with the increase of the winding angle of the tape.