【作者】 裴晓梅；

【导师】 梁鸿生；

【作者基本信息】 西安理工大学 ， 检测技术与自动化装置， 2003， 硕士

【摘要】 本文首次将频谱分析的思想引入到了涡流检测中，并利用虚拟仪器技术，研制开发出基于LabWindows／CVI软件平台的涡流检测虚拟仪器系统，从而使得涡流检测方法实现金属导体参数测量过程变得简单容易，分析结果直观，并通过曲线描述方法赋予了涡流检测仪器一定分析功能。 深刻理解涡流检测的基本原理，是选择涡流检测基本方案的理论基础。论文第二章从多个角度分析了电涡流检测原理，分别对涡流检测等效电路、涡流检测系统的频率响应、涡流传感器输出信号的频谱做了分析。并对涡流检测原理的频率响应分析和频谱分析二者之间的关系以及等效电路分析和频率响应分析二者之间的关系分别做了探讨。最后通过数学公式推导从理论上以及实验数据论证了频谱分析法解决泵筒内壁表面硬度参数测量的可行性． 涡流检测虚拟仪器的开发离不开强大的软件工具。而虚拟仪器技术以及具有强大信号处理及分析功能的软件LabWindows／CVI则为本课题提供了这个工具。论文第三章就涡流虚拟仪器系统开发做了研究。首先介绍了虚拟仪器技术及开发虚拟仪器的软件LabWindows／CVI。然后针对第三方厂家生产数据采集卡在该软件环境下的函数调用进行了阐述。并设计了具有数据采集、频谱分析、硬度及间距参数显示和硬度参数曲线变化等功能的多个虚拟仪器面板。最后给出了可执行程序的生成及软件打包处理，从而得到一台真正的涡流检测虚拟仪器。 频谱分析的理论以及数字信号处理理论为在LabWindows／CVI软件下对涡流传感器输出信号进行分析和处理提供了理论基础，为实现各种功能的软件编程提供了算法依据。论文第四章就频谱分析的概念以及计算工具傅立叶变换做了阐述，特别是针对涡流传感器输出为周期信号的特点，对周期信号取样及频谱分析做了详细介绍。最后针对频谱分析中应该注意的几个问题做了探讨。在频谱分析理论的指导下，对采样点数选择以及采集进来的信号进行初始相位统一化处理等数据处理进行了 西安理工大学硕士学位论文分析。 论文第五章通过BP神经网络对所得到的频诺值进行数据拟合最终实现硬度、测量间距参数的测量。通过对检验样本测量得到的测量值与理论值的比较及相对误差结果，得出结论即采用本方案满足系统测量精度要求的。 论文第六章对实验数据进行了分析。并对涡流检测系统中可能出现的名种误差原因做了分析。更多还原

【Abstract】 The frequency spectrum analysis is introduced to the eddy current testing in this paper. Using the virtual instrument technique, the eddy testing virtual instrument system based on LabWindows/CVI is developed to make the metal parameters testing easier and analysis results direct. Also the analysis function is added to the eddy testing instrument through graph describing.Understanding the basic theory of eddy testing is the basis of selecting eddy testing plan. In chapter 2, eddy testing theory is analyzed from several aspects. The equivalent circuit of eddy current testing, frequency response of eddy current testing system and frequency spectrum of eddy current sensor output signal is analyzed respectively. Also, the relation among these analysis methods is discussed. Finally by mathematic derivation, the feasibility of solving the measurement to hardness parameters by frequency spectrum analysis is proved from both theory and experiment data.The development of eddy testing virtual instrument must be based on powerful software tools. The virtual instrumentation technique and LabWindows/CVI with the powerful signal processing and analysis function provide this tool for the project. In chapter 3, the system of eddy testing virtual instrumentation is studied. The virtual instrumentation technique and LabWindows/CVI is firstly introduced. Then the function calling of the third DAQ under LabWindows/CVI is discussed. The multi-virtual panel is designed performing data acquisition function, frequency spectrum analysis, parameters computation, result displaying and graph drawing function etc. Finally, the method of executive program producing and the software packing are given so as to make a true virtual instrumentation.The theory of frequency spectrum analysis is the theoretic basis of processing and analyzing the output signal of the eddy current sensor and also the algorithm reference of software programming. The frequency spectrum idea and the computation tool-Fourier transformation are discussedand the frequency spectrum to the periodic signal is expounded. Finally several problem about frequency spectrum analysis are discussed. With the spectrum analysis theory guided, the data processing about selecting sampling number and the primary phase etc is also analyzed.In chapter 5, the parameters of hardness and distance are obtained by BP neural network computing the three frequency spectrums. And through the comparison with the testing value and theoretic value, it’ s concluded that the frequency spectrum analysis method meets the system measurement requirements.In chapter 6, the experiment data is analyzed. And the error reasons in the eddy testing system are analyzed.更多还原