A contribution to the experimental validation in Lorentz force eddy current testing
A contribution to the experimental validation in Lorentz force eddy current testing
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对洛伦兹力涡流检测实验验证的贡献
DOI：
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发表时间：
2017
期刊：
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通讯作者：
M. Carlstedt
中科院分区：
文献类型：
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作者：
M. Carlstedt
导电性部件和组件的无损检测（NDT）是我们日常生活中几乎所有技术产品生命周期中不可或缺的一部分。特别是在汽车和航空航天工业中，使用现代轻质材料可以开发出更强大、更高效的机械结构。这些重型部件必须在生产阶段以及随后的运行阶段对其结构完整性进行测试，以确保安全可靠地运行。本文研究的洛伦兹力涡流测试（LET）是能够满足这些行业日益增长的需求的测试方法之一。本文首先简要介绍了无损检测的最新技术，并介绍了所涉及的工业市场。随后，介绍了运动感应涡流检测方法领域的相关工作。特别侧重于在以前的可行性研究中进行的实验调查。考虑与测量原理相关的物理现象，通过量纲分析，可以深入了解电磁参数和几何参数的相互作用。一项全面的数值研究伴随着这项研究，并导致了实际标度定律的阐述。本文最全面的部分是对LET的测量过程进行了分类和系统描述，并对所开发的实验装置的测量性能进行了代表性的概述。在这项研究中，使用了一种新的多组件传感器系统，它可以同时记录发生的测量力以及它们对测量装置的加速效应。通过将所涉及的物理量作为随机变量，将理想（确定性）测量过程扩展为实际测量过程。分析表明，测量结果的统计特性，如物理量的均值和方差，并不是与时间无关的。因此，单次测量的测量信号不能为非平稳测量过程提供完整的测量结果。因此，我们建议将连续测量的人工信号集合在一起，从而首次能够在LET中计算完整的测量结果。实验装置动力学的力学建模是LET测量过程理论描述中的另一个新颖之处。为此，通过两个实际相关的示例，给出了系统识别过程的示例性。这允许通过适当的信号预处理和模型特定参数估计对机械系统进行直接建模。基于这些力学模型，给出了数字滤波器的设计过程，以补偿外加力传感器的频率相关灵敏度。
Nondestructive testing (NDT) of electrically conductive components and assemblies is an integral part of the product life cycle of almost every technical product in our daily life. Particularly in the automotive and aerospace industry, the use of modern light-weight materials allows the development of ever more powerful and efficient mechanical structures. These heavy duty components must be tested for their structural integrity in the production phase as well as in the subsequent operating phase in order to ensure safe and reliable operation. Lorentz force eddy current testing (LET), which is investigated in this work, is one of the testing methods that are capable to meet the growing requirements of these industries. The thesis begins with a brief introduction into the state-of-the-art in NDT and a presentation of the involved industrial markets. Subsequently, the related work in the field of motion-induced eddy current testing methods is described. A particular focus is on the experimental investigations carried out in previous feasibility studies. The consideration of the physical phenomena relevant to the measuring principle, by means of the dimensional analysis, allows a deepening insight into the interactions of the electromagnetic and geometric parameters. A comprehensive numerical study accompanies this study and leads to the elaboration of practical scaling laws. The most comprehensive part of the thesis is the classification and the systematic description of the measurement procedure of LET and a representative overview of the measurement performance of the developed experimental setup. In this study, a novel multi-component sensor system is used, which allows simultaneous recording of the occurring measuring forces as well as their accelerating effect on the measurement setup. The idealized (deterministic) measurement process is extended to a real measurement process by considering the involved physical quantities as random variables. It is analyzed that the statistical properties of the measurement result, e.g. mean and variance of a physical quantity, are not independent of time. Thus, a measurement signal of a single measurement cannot provide a complete measurement result for the non-stationary measurement process. Therefore, the assembling of an artificial signal ensemble of sequential measurements is suggested, which for the first time enables the calculation of complete measurement results in LET. The mechanical modeling of the dynamics of the experimental setup is another novelty in the theoretical description of LET measurement process. For this purpose, the process of system identification is presented exemplary for two practically relevant examples. This allows a straight modeling of the mechanical system by an appropriate signal preprocessing and a model-specific parameter estimation. Based on these mechanical models, the design process of digital filters is shown in order to compensate the frequency-dependent sensitivity of the applied force sensor.