高速轨道钢早期损伤磁记忆定量化评价的力-磁-热耦合理论与实验研究

Although high-speed rail steel has advantages such as high strength, it has its own shortcomings such as insufficient toughness and short crack propagation life, resulting that the macro-defect of high-rail steels is easier to develop and may lead to serious accidents such as train derailment, and affecting its integrity and service safety. For high-speed rail steel, it is of great practical significance and scientific value to explore new non-destructive testing methods and achieve effective prediction of its early damage. Metal magnetic memory method is a cut-to-edge subject in the field of non-destructive testing. In principle, it can provide effective early warning of the early damage of ferromagnetic materials such as high-rail steels. However, in practice, it still has many problems and challenges such as lack of quantitative capability, complex influencing factors, and failure to apply criteria. This project investigates the thermo-magneto-elastoplastic coupling theory and experiments regarding quantitative evaluation of high-speed rails via magnetic memory method. In this project, 1) the theory of multi-field coupling mechanics is introduced to solve the problem of insufficient quantification; 2) combination of theoretical modeling and experimental verification is adopted to clarify the mechanism and coupling mechanism of each influencing factor of magnetic memory signals; 3) a new criteria is extracted for metal magnetic memory methods through the correlation of evolutionary data in the fatigue process to solve the problem that the existing criteria cannot be applied for practical application. The research results can provide some theoretical foundations for metal magnetic memory method, improve its application capabilities, and provide strong support for the service safety of high-speed railways.

虽然高速轨道钢具有高强度等优势，然而其自身存在韧性差、裂纹扩展寿命短等不足，导致高速轨道钢的宏观缺陷更易发展，严重影响其完整性及服役安全。针对高速轨道钢探索新的无损检测方法，实现早期损伤有效预报，具有重大现实意义和科学价值。磁记忆方法属无损检测领域前沿，原理上可实现高速轨道钢等铁磁材料早期损伤的有效预警，但实际应用仍面临着定量能力不足、影响因素多杂、判据无法应用等挑战。本项目针对高速轨道钢材料早期损伤的磁记忆定量化评价开展理论和实验研究，内容包括：1)基于多场耦合力学理论解决定量化程度不足问题；2)采用理论建模和实验验证相结合方法，澄清磁记忆信号各影响因素的作用机理与耦合机制；3)结合疲劳过程中演化数据的相关关系，提炼检测新判据，解决现有判据无法实际应用的问题。本项目研究成果可为磁记忆方法的定量化建立理论基础，提高其实际应用能力，为高速铁路的服役安全提供有力支撑。

随着我国的高速铁路正由大规模建设时期逐渐走向安全运营时期，如何保障铁路安全、稳定、可靠的长期运行将会成为我国铁路运输面临的重大问题。磁记忆检测技术被誉为21世纪的新型无损检测技术，为解决高速轨道钢应力集中等早期损伤检测问题提供了可能。本项目针对磁记忆检测技术中的磁热弹塑性多场耦合问题开展应用基础研究。力磁本构方面，发展了铁磁材料力磁耦合本构模型及参数标定方法，研究了微弱磁场下铁磁材料的磁-热-弹塑性多场耦合特征。磁记忆理论方面，基于力磁本构进展建立了金属磁记忆无损检测的定量化理论，发展了金属磁记忆检测技术的有限元分析方法和磁偶极子解析理论，澄清了磁场、载荷、温度、弹塑性状态等对磁记忆检测的影响规律。磁记忆检测实验方面，搭建金属磁记忆检测平台发现了磁记忆检测信号的磁弹塑性耦合现象及机理，提出了基于热致磁变原理的铁磁性金属材料轴向应力检测的新方法；针对磁检测技术应用中提离扰动导致的评价能力恶化问题，提出基于双磁敏元件的探头设计以及基于双提离探头的漏磁检测缺陷定量评价方法。此外，针对材料的疲劳和损伤力学模型开展了初步探索，针对磁巴克豪森噪声检测技术开展了数值模拟的可行性探索。项目研究成果为提升金属磁记忆检测技术的定量评价奠定了理论基础。