Study On Peridynamic Simulation Of Superconducting Composites

Superconducting composites are widely used in many high-tech fields such as long-distance power transmission,large-scale nuclear fusion devices,nuclear magnetic resonance imaging devices and superconducting magnetic suspension devices due to excellent electromagnetic properties.However,high temperature superconducting materials are prone to damage and fracture under the action of extremely low temperature,strong electromagnetic field,high current carrying and complex mechanical load,which leads to the degradation of superconducting properties of materials and greatly affects the stable operation of superconducting devices in extreme service environments.Therefore,it is urgent to use effective numerical methods to simulate the damage behavior of high temperature superconducting composites.In this paper,the mechanical response of high temperature superconducting composite wires under external loads is simulated systematically based on the peridynamic method.The complex elastoplastic deformation and filament damage are calculated.In addition,the peridynamic method is also extended.The main research works of this paper are as follows:Firstly,the ordinary state-based peridynamics theory of thermomechanical problem in composites is introduced,and its discrete calculation and corresponding numerical realization flow are given.For static problems with small deformation,a constitutive linearization form of peridynamics is derived by using the Taylor expansion formula of multiple functions.The OpenMP parallel computing code of peridynamics is presented to improve the computing speed.The accuracy of the ordinary state-based peridynamics are verified by examples of linear elastic materials.Secondly,the elastoplastic deformation of Bi-2212 round wire and the damage of the superconducting filament are simulated by using ordinary state-based peridynamics.Combining the ordinary state-based peridynamics with J2 plastic theory,the extension of the peridynamic method to elastoplastic materials is realized with the return mapping algorithm.On this basis,the detailed modeling and simulation of Bi-2212 composite round wire are carried out,considering the residual stress caused by cooling and the fracture toughness of Weibull distribution.The simulation results obtained by combining the nonlinear hardening function are in good agreement with the experiment results.The degradation of the critical current with tensile strain is explained from the point of view of material damage.The protective effect of the plastic deformation of the alloy on the filament is found,and the damage characteristics of the filament bundle under bending and torsional loads are given.Finally,the method of non-ordinary sate-based peridynamic is extended.Based on the nonlocal deformation gradient tensor,the accurate calculation of large deformation for hyperelastic material is realized under the framework of non-ordinary sate-based peridynamics,and the large deformation fracture behavior of materials is simulated.Subsequently,the finite deformation J2 plastic theory is introduced into the non-ordinary sate-based peridynamic model,and the large strain plastic deformation of elastoplastic materials is simulated,which is expected to be used in the large deformation fracture simulation of superconducting elastoplastic composite materials.