基于磁适应检测技术的关键和基础问题研究

Magnetic adaptive test technology is a new nondestructive testing method which can high precisely test and evaluate the stress concentration, fatigue damage and the change of the structure of the whole or part of the ferromagnetic component. The magnetic adaptive parameter is the most sensitive magnetic parameter for the change of the micro-structure of the measured specimens, and it is the two-variables function of the magnetizing field and the maximum magnetic field, which related to low magnetic field magnetizing technology closely. From the three aspects of experimental exploration and theoretical analysis and finite element simulation, the basic problems involved in the magnetic adaptive testing technology are studied for further. Based on the experimental data and the results of simulation and the theoretical exploration result, this paper focuses on the physical mechanism of magnetic adaptive testing technology. The mathematical relational model of magnetic adaptation parameters and the micro-structure change will be established, which can reveal the physical essence of magnetic adaptive testing parameters can reflect stress concentration and fatigue damage state at high sensitively. Study the optimization mechanism of the key parameters, establishes the relation model of key parameters and testing signal, establishes the relation model of micro-structure characteristics of components and testing signal; Experiment study on the regularity of magnetic adaptive testing with the stress concentration and fatigue damage, to establish linked mathematical function relationship; Study the physical nature and primary and secondary relations of related factors which can affect detection sensitivity, expanding the application field to establish scientific magnetic adaptive testing evaluation method. The research results can provide reference to further research and widely application for the magnetic adaptive test technology.

磁适应检测技术是可高精度评价铁磁构件整体或部分区域应力集中、疲劳损伤 、组织结构变化的检测方法。磁适应参量是对待测构件微观结构变化最灵敏的磁参量，是磁化场和最大磁化场的二元函数，与低场技术磁化密切相关。从试验探索、理论分析和有限元仿真三方面对磁适应检测技术所涉及的基础问题进行深入研究。以试验研究数据为基础，以仿真分析结果为佐证，以理论探索为主线，重点研究基于磁适应检测技术的物理机理, 建立磁适应参量与应力集中等微观组织变化的数学模型，揭示磁适应检测参量可高灵敏反映应力集中、疲劳损伤的物理本质；研究关键参数的优化机理, 建立关键参数与检测信号和待检构件组织微结构特征的关系模型；试验研究磁适应检测参量随应力集中状况、疲劳损伤程度等微观结构变化的规律，建立数学模型；研究影响检测灵敏度相关因素的物理本质和主次关系，拓展应用领域，建立科学的磁适应检测评价方法。研究成果可为该检测技术的深入研究提供借鉴

磁适应检测技术是一种评价铁磁构件整体或部分区域应力集中、疲劳损伤 、组织结构变化的检测方法，是对磁记忆检测技术的进一步研究。具体研究了基于磁适应检测技术的物理机理和检测数学模型；研究了关键参数的优化方法, 建立了关键参数与检测灵敏度的关系规律；试验研究了磁适应检测参量随应力集中、疲劳损伤、材料组织等微观结构变化的规律；研究了影响检测灵敏度相关因素的物理本质及主次关系。. 采用振动样品磁强计(Lakeshore VSM)对几种碳素钢进行了低场磁化规律测定， 证明了常用碳素钢材料的磁适应参量即是初始磁导率。对平板待检试件和圆棒待检试件，根据基尔霍夫磁路第一定律和第二定律, 研究了检测信号与微分磁导率的关系。研究可知，检测信号与微分磁导率成线性关系，证明了可通过检测信号与标准试块相比较，可直接测定待测试件的初始磁导率，进而判定构件的损伤状况。. 重点研究了传感器的设计方法。对恒压源和恒流源情况的激励频率进行了优化设计。研究了激励电压幅值、激励线圈匝数、检测线圈匝数及外加拉应力对传感器最优检测频率的影响。对于恒压源情况，检测信号与激励频率有关，检测灵敏度随频率的增大，先增加后减小。存在一极值点，即存在一最优检测频率使得检测灵敏度最大。最优检测频率与外加拉应力有关。对于恒压源情况研究发现，检测灵敏度随频率的增大，先增加后减小再增加，最后趋于定值。存在两个极值，即存在两个最佳频率。其最佳频率的选择可根据缺陷的特征进行选择，检测较浅裂纹选用较高频率，检测较深裂纹可选用较低频率。设计研制一种“M”形的平板裂纹损伤检测的传感器。以感应信号差分输出的方式实现了对铁磁构件表面裂纹的检测和区域应力集中程度的检测。该研究成果可广泛应用于钢铁、电力、航空等工业生产检测领域，可早期检测钢铁材料的应力集中分布状态和疲劳损伤程度，对安全生产具有重要意义。.

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