高温超导层状复合带材多场耦合作用下剥离失效机理研究

Earth-Barium-Copper-Oxide (ReBaCuO) high-temperature-superconductor coated conductor tapes, have become a hot issue and the developing direction for the future in the field of superconducting science and technology due to their high critical magnetic field, high current density, and high critical temperature of superconducting state realized in the liquid nitrogen environment. As a laminated electromagnetic functional composite material, the delamination failure, especially, the mechanical properties seriously affect its superconductivity and application in electromagnetic thermal multifield environment. At present, there are some problems in the research of delamination behavior of ReBaCuO composite tapes, such as unclear delamination mechanism in coupled multifield and difficulty in multiscale structure modeling. In this project the mechanical behaviors and the influences on superconducting properties of ReBaCuO coated conductor tapes during delamination failure process in ultra-cryogenics and multifield will be carried out based on multifield and multiscale quantitative simulation modeling technology and of basic experimental characterization method to reveal the delamination mechanism and mechanical-electrical degradation behavior under extreme conditions. Furthermore, the quantitative analysis method for multiscale coupled behavior of mechanical-electrical degradation under multifield is to be presented to clarify the inherent regularity of mechanical-electrical degradation caused by delamination failure of ReBaCuO coated conductor tapes under working conditions. The research of this subject will provide an efficient and accurate analysis method for the study of extreme multifield structural failure of ReBaCuO coated conductor tapes. This work has some enlightenment for the study of multifield coupling behavior and mechanical failure behaviors of other laminated intelligent composites.

因具有高临界磁场、高电流密度及液氮环境下可实现超导态等显著优点，ReBaCuO高温超导带材已成为超导科学与技术领域的研究热点。作为典型的多层电磁功能复合材料，其层间剥离失效，特别是电磁热多场环境下的力学性能严重影响其超导性能与应用。目前，ReBaCuO复合带材剥离行为的研究存在着多场耦合作用下剥离机理不明确、多尺度结构建模困难等问题。本课题将基于多场、多尺度定量数值仿真建模技术与基础实验表征方法，探讨低温多场下带材剥离破坏过程的力学特性及其对超导性能的影响，揭示剥离机理与力电失效行为；发展多场下多尺度剥离与力电退化耦合行为定量分析方法，从而明确超导带材工况下剥离破坏引起的力学失效与超导性能退化的内在规律。本课题的研究将为ReBaCuO复合带材极端多场下结构破坏的研究提供高效、准确的分析方法，推动其极端多场下的应用。该工作对其他层状智能复合材料多场耦合行为及力学破坏行为的研究具有一定的启发。

本项目紧密围绕二代高温超导复合材料层间剥离损伤特性及力电退化规律问题展开研究。发展大幅变温下REBCO高温超导复合带材剥离行为的混合维度高保真有限元模型，高效准确地实现了力学作用下带材剥离行为研究，揭示了传统砧测法误差原因，可用于分析带材剥离破坏机理，并为优化方案提供指导；发展了全新的REBCO高温超导复合带材剥离强度的测试方法，相比于传统的砧测法，该方法显著降低了实验结果的离散程度，结果表明拉伸界面强度平均值2.34MPa，最大相对误差7.3%，剪切界面强度平均值11.27MPa，最大相对误差8.6%；开展拉扭组合变形下REBCO超导带材力电退化实验研究并建立临界电流唯象模型，结果表明基底的塑性变形先于超导涂层的失效，传统的0.2%塑性失效判据高估了带材的安全使用范围，揭示复合荷载作用下力电失效耦合行为，为应用中超导带材结构安全判据提供了参考；建立高温超导线圈结构界面开裂的多尺度定量分析方法，实现高温超导线圈工况下剥离破坏的预测，探明高温超导磁体通过降低外径内径比以及在环氧树脂中掺杂负热膨胀系数颗粒的结构优化方案，为工程设计与应用提供指导。通过以上的研究，课题组建立和完善了二代高温超导复合带材与线圈结构力学行为尤其是界面开裂行为与力电失效特性的数值与理论分析框架、有效的定量分析手段和基础实验测试平台，揭示出力学与超导性能相互作用的规律，为高温超导电缆与磁体的结构设计与安全运行提出了若干有益工程建议，可为我国新型超导电缆和大型超导磁体的研发提供必要的理论模型、数值方法与实验手段的支撑。在本项目支持下，总计发表超导与力学相关领域SCI收录论文9篇，授权发明专利1项、实用新型专利4项。协助指导从事超导力学研究的3名博士研究生与3名硕士研究生。完成了课题的各项研究内容和预设目标。