【作者】 宋运兴；

【导师】 李亮；

【作者基本信息】 华中科技大学 ， 电气工程， 2012， 博士

【摘要】 本文对高场磁体的多物理场耦合作用机理进行了详细的研究。本文分为两部分：第一部分研究脉冲磁体的多物理场耦合作用机理。主要工作包括：第二章建立了完整的多级脉冲磁体放电过程二维轴对称电磁热多场耦合模型,充分考虑了脉冲磁体导体的热效应、磁致电阻效应以及涡流效应。在此基础上研究了单级、两级以及三级脉冲磁体放电过程中电阻、电感、磁场、电流密度及温度的变化规律；研究了闭合导电环对脉冲磁体磁场波形的影响；研究了轴向开冷却通道对提高脉冲磁体的冷却效率的作用。第三章建立了完整的基于小应变条件的多级脉冲磁体二维轴对称静态弹塑性力学分析模型,充分考虑了初始应力和初始应变、轴向压力、洛伦兹力、热应力和导体等弹塑性材料的Bauschinger效应等因素。该模型能计算脉冲磁体从制作到放电过程整个加载历史以及循环加载,并能预测磁体的疲劳寿命。提出了新的脉冲磁体失效准则：导体等弹塑性材料的失效用最大等效塑性应变超过材料的极限塑性应变来判断即应变失效准则；纤维加固材料等正交各项异性弹性材料的失效用最大von Mises等效应力超过材料的极限抗拉强度来判断即应力失效准则。基于该模型和失效准则,采用有限元法,作者研究了单级脉冲磁体、两级脉冲磁体以及三级脉冲磁体的弹塑性力学行为。对于单级磁体,研究了导体等弹塑性材料的不同材料模型对脉冲磁体失效的影响；研究了动态响应对脉冲磁体失效的影响；研究了导体等弹塑性材料的Bauschinger效应对脉冲磁体失效的影响；对于多级脉冲磁体,还研究了互感对脉冲磁体弹塑性力学行为的影响。第四章研究了制作工艺和放电过程对脉冲磁体极限指标的作用机理,包括：预应力对脉冲磁体失效的影响、轴向压力对脉冲磁体失效的影响、锻炼放电过程对脉冲磁体失效的影响以及塑性变形对脉冲磁体不可逆电感的影响。第二部分研究超导磁体的多物理场耦合作用机理。主要工作包括：第五章建立了基于不同优化算法的高温超导磁体电磁设计优化模型。以一个Bi系高温超导磁体为例,比较了序列二次规划算法和遗传算法的寻优性能。第六章建立了超导磁体失超传播分析数值模型,充分考虑了交流损耗、焦耳热损耗、对流传热以及外界扰动。基于该模型,采用有限元法,作者对一个低温超导磁体进行了失超传播分析。更多还原

【Abstract】 In this dissertation, a detailed study of multi-physics coupling mechanism in high-field magnets is carried out. The dissertation is divided into two parts:Part1presents the multi-physics coupling mechanism in pulse magnet. The main conclusions are:In chapter2, we present a complete coupling model of the electromagnetic and heat diffusion of two-dimensional axisymmetric multi-stage pulse magnet of the discharge process, fully taking into account the thermal effect, the magneto-resistance effect and the eddy current effect. On this basis, the change rules of the resistance, the inductance, the magnetic field, the current density and the temperature of the single-stage, two-stage and three-stage pulse magnets are given. Influence of the closed conductive ring on the magnetic field is studied. Effect of the axial cooling gap to improve the cooling efficiency of the pulse magnet is studied.In chapter3, we present a complete2D axisymmetric static elastic-plastic mechanical analysis model of multi-stage pulse magnet based on small strain condition, fully taking into account the initial stress and initial strain, the axial loading by the end plates, the Lorentz force, the thermal stress and the Bauschinger effect of the elastic-plastic materials such as conductors. This model can calculate the entire loading history from fabrication to discharge process, as well as cyclic loading, and can predict the fatigue life of pulse magnet. A new failure criteria of pulse magnet is presented:the maximum equivalent plastic strain exceeding the limit plastic strain is used to estimate the failure of elastic-plastic materials such as conductors; the maximum von Mises stress exceeding the ultimate tensile strength is used to estimate the failure of the orthotropic elastic materials such as fiber reinforcement materials. Based on the model and the new failure criteria, the elastic-plastic mechanical behavior of single-stage, two-stage and three-stage coils is carried out by finite element method. The impact of the different stress-strain curve models, the dynamic response and the bauschinger effect on the failure of the single-stage coil is studied. The impact of the mutual inductance on the elastic plastic mechanical behavior of the multi-stage coils is also studied. In chapter4, the mechanism of the fabrication process and discharge process of the limit indicators of pulse magnet is studied, including the impact of the prestress applied during coil winding, the axial loading by the end plates, and the discharge process of training on the failure and the plastic deformation of the irreversible inductance of the pulse magnet.Part2presents the multi-physics coupling mechanism in superconducting magnet. The main conclusions are:In chapter5, we present an electromagnetic design optimization model of the high temperature superconducting magnet based on different optimization algorithms. The optimization performance between SQP and GA is compared based on a high temperature superconducting magnet made by Bi-2223/Ag.In chapter6, we present a numerical analytical model of quench propagation of superconducting magnet, fully taking into account AC loss, Joule heat loss, convective heat transfer and external disturbances. On this basis, the quench analysis of a low temperature superconducting magnet is performed by finite element method.更多还原