【作者】 孙志远；

【导师】 杨学山；

【作者基本信息】 中国地震局工程力学研究所 ， 防灾减灾工程及防护工程， 2012， 博士

【摘要】 随着科技的不断进步和社会经济实力的提高，每年建筑用钢材需求都在数千万吨。钢材作为结构最主要的构件，往往都担负着巨大的载荷。对建筑结构钢材料实际受力状态的直接测试方法成为当代结构健康诊断领域一个重要的研究课题，其研究成果极具工程应用价值，同时势必将推动对结构安全性评价的整体分析水平。本文在综述了国内外常用的磁学铁磁材料检测方法的基础上，着重研究了基于磁力耦合法的建筑钢材料应力检测技术。并依此为研究背景，通过理论分析、实验和先进的仿真技术手段，全面地研究了该检测技术的基本理论和实用技术，主要研究工作如下：（1）根据建筑钢材料的构成成分，结合铁磁学理论研究了应力及杂质对其磁畴和磁畴壁的影响机理。分析得到应力的施加使得晶体的应力能增大和磁化方向随应力方向发生变化的结论；杂质使得磁畴的结构变得十分复杂，需要通过大量的实验来验证对应力检测方法的影响范围。阐述了利用技术磁化进行钢材料应力检测的一般规律，为建立磁力耦合关系理论模型提供了必要的理论支持。（2）利用Joule效应的逆效应证明了应力—伸缩—磁场的变化规律。讨论了在外磁场和应力作用下铁磁晶体内其总自由能的主要组成，并根据能量守恒定律和热力学动态平衡原理，建立了应力对磁特性参量影响的数学模型方程，并对数学模型方程进行解析，获得了在不同磁场强度下钢材料应力与其相对磁导率变化的计算结果。（3）依据理论分析的钢材料应力状态与其磁导率的关系，提出了对材料进行技术磁化并通过电磁感应原理进行应力检测的实用方法。设计了采用脉冲和正弦信号两种方式作为激磁信号的激磁电路；根据被测材料形状和使用状态设计了管筒式和U型磁路式两种结构磁探头，对其磁回路进行了磁路分析；并利用电磁场有限元仿真软件对探头进行了优化设计。（4）开发了相应的应力检测系统样机，对主要参数进行了试验分析。根据不同的探头结构和激磁方式设计了相应的试验方案，利用标定法在万能材料试验机上对检测系统样机进行主要技术参数的校准。对于该数据在进行处理后与材料应力关系进行了四阶曲线拟合，其相关系数都在0.98以上。并对同一材料其杂质对检测值的影响进行了分析。从试验结果看，一般厂家生产的工程材料这种误差影响最大值小于3%。（5）利用FLUX电磁场仿真软件对系统整体进行电磁场分析，了解材料内磁场大小、分布等信息，通过软件计算出应力与材料磁导率的对应关系，并且得到与理论相一致的结论。最后，提出了试验与数值模拟相结合的方法对某种材料应力值进行标定，代替传统的试验标定法并取得了良好的仿真结果，其中U型探头测量钢筋应力的仿真效果最好，其误差最大值小于1%。最后，总结了全文的主要研究工作，指出了论文的不足之处以及后续的研究重点。更多还原

【Abstract】 It is demanded for millions and millions tons of construction steel material eachyear with continuous improvement of technology and social economic power. As themain structural steel components, they are often responsible for a huge load. Therefore,the direct detection method of the actual building steel stress state has become animportant research topic in the contemporary field of structural health diagnosis. Theresearch achievement has great value in engineering and is bound to promote the overallanalysis level of the structural safety evaluation.In this paper, the domestic and foreign common detection methods based onferromagnetic materials are summarized, and focused on the stress detection technologyof structural steel material based on the magnetic coupling. And as the background forthe study, the basic theory and application methods is researched systematically throughtheoretical analysis, experimental and model simulation techniques, the main researchwork are as follows:(1) According to the composition of construction steel materials, the basic principleof stress and impurity impacting on magnetic domain and domain wall are researchedcombined with the theory of ferromagnetic. The analysis shows that the stress makes thecrystal stress energy increasing and the magnetization direction changing with the stressdirection. The impact of impurities on the magnetic domain is very complex so weshould verify the influencing range to the through a large number of tests. The generalrules of detecting steel stress is elaborated by technical magnetization, and whichprovides the necessary theoretical supports for establishing the theoretical model ofmagnetic coupling.(2) Through Joule inverse effect the effect of the stress stretching the magneticfield is demonstrated. The main component of the total free energy of ferromagneticcrystals is discussed under the external magnetic field and stress, and in accordance withlaw of conservation of energy and thermodynamic principles of dynamic equilibrium themathematical model equation of stress affecting the magnetic properties is established,and the mathematical model equations is parsed, and the calculation result between stressof steel material and their relative permeability is obtained in the different magnetic fieldstrength.(3) A practical method for stress detecting is proposed that is achieved by technicalmagnetization and electromagnetic induction principle based on the relationship oftheoretical analysis between the stress state of steel and its magnetic permeability. Thecorresponding circuit is designed by using the two ways of pulse and sinusoidal signal asthe excitation signal; based on the measured shape and using state of material two kindsof magnetic probes of the U-model and cylinder is designed. Its magnetic circuit analysisis carried out, and the probe has been optimized by finite element simulation software.(4) The prototype of corresponding stress detection system is developed, and themain parameters are analyzed by experiments. According to the different probe structureand excitation the test scheme are designed. By use of calibration method the maintechnical parameters of the detection system prototype is calibrated in the universaldetecting machine to obtain the corresponding test data. The relations of the processeddata and material stress are in a fourthorder curve fitting, and the correlation coefficientsare0.98or more. The impact of the detection value on same materials with the impurityis analyzed. From the test results, this maximum impact of the materials by different manufacturers is less than3%.(5) By use of FLUX electromagnetic field simulation software the electromagneticfield of whole system is analyzed including the size of the magnetic field and thedistribution inside the material, and through the software the correspondence betweenstress and material permeability is calculated and that is consistent with the theoreticalconclusions. Finally, it is proposed that the value of material stress is calibrated by thecombining method of test and numerical simulation to replace the traditional calibrationmethod and obtain good simulation results，which the U-model measurement has the bestsimulation results and the maximum error is less than1%.At last, this dissertation reviews the whole research work and sums up shortcomingsin it，some important issues are expected to be perfected in the near future.更多还原