涡流检测信号处理方法.doc
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涡流检测信号处理方法,摘要涡流检测是基于电磁感应原理的一种常规无损检测方法，具有检测速度快，灵敏度高，非接触测量等特点，已经在航空、冶金、化工、机械等诸多工业领域得到了广泛应用。本文针对船舶焊缝裂纹进行检测，将涡流检测技术、数据采集技术和数据分析处理技术有机结合起来，拟开发适合在线检测的智能化涡流检测系统。本文主要研究内容包括：1）在深入分...
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摘 要
涡流检测是基于电磁感应原理的一种常规无损检测方法，具有检测速度快，灵敏度高，非接触测量等特点，已经在航空、冶金、化工、机械等诸多工业领域得到了广泛应用。本文针对船舶焊缝裂纹进行检测，将涡流检测技术、数据采集技术和数据分析处理技术有机结合起来，拟开发适合在线检测的智能化涡流检测系统。本文主要研究内容包括：
1）在深入分析涡流检测基本原理的基础上，设计完成了一套以单片机和CPLD为控制核心的双通道实时涡流检测数据采集系统。该系统硬件电路包括信号放大、滤波、模数转换、CPLD、单片机及其通信电路等，软件设计主要涉及单片机C51程序、CPLD的VHDL程序、PC机VC程序等。该系统结构简单，性能稳定，能较好地满足实际需求。
2）对涡流传感器的静、动态特性进行分析是评价该传感器性能及实现在线补偿的重要环节之一。本文在了解传感器静态、动态性能指标的基础上，采用多种方法建立了涡流传感器的静、动态数学模型，并比较了相应建模效果，为下一步传感器特性进行在线补偿做了铺垫。
3）为了减小检测过程中的各种外界干扰和噪声，准确判断数据，对涡流响应信号进行了预处理，剔除数据中的无意义坏点，对数据进行平滑处理；应用小波变换理论中小波的多尺度边缘检测原理对信号进行除噪处理，极大的提高信号的信噪比，并提取了表征裂纹的特征量。
4）利用所建立的有限元模型对涡流传感器参数进行了仿真研究，分别讨论了线圈内径、外径、高度和放置方式对传感器性能的影响，为涡流传感器结构参数的优化提供了理论参考。采用优化后的涡流传感器，仿真分析了不同线圈位置，缺陷的长度、深度，埋藏深度和截面形状对检测线圈磁感应强度分量的影响，为实际检测过程中工件缺陷的定量分析奠定了基础。
关键词 涡流检测；数据采集；数据处理；特性建模；有限元仿真
Abstract
Eddy current testing based on the electromagnetic induction principle is one of the regular nondestructive testing methods. Because it has the advantages of high speed, high sensitivity and non-contact measurement, it is widely applied to the manufacture field of aviation, metallurgy, chemical and mechanical industry. In order to test weld metal cracking in ship industry, a new eddy current testing system that suits for on-line detection is developed. The intelligence system is composed of eddy current inspection theory, data acquisition and processing technology and data analysis technology. The main contents are the following:
1) Based on the theory of eddy current testing technology, a data acquisition system based on MCU and CPLD (Complex Programmable Logic Device) as core control units has been designed. The hardware circuit includes signal amplification, filtering, A/D conversion, CPLD interface and MCU communication circuit. The software design includes the C51 program, VHDL program, VC program and so on. The system has simple structure and stable performance, which can meet the requirements of testing cracks.
2) Analysis on static property and dynamic property of eddy current sensor is the important point of eva luating sensor property and realizing on-line compensation. Based on the study of static and dynamic property, the mathematic models are built by various methods, and the results are compared. This work sets the stage for compensation.
3) In order to reduce the external interference and noise and judge the data accurately, the response signal of eddy current is preprocessed and the insignificant isolated points in the data are eliminated. Wavelet multi-scale edge detection technique is used to eliminate noise, improve the signal to noise and extract characteristic quantities.
4) Eddy current sensor is simulated by finite element model, and then the influences of coil’s diameter and placing mode are discussed. So this work provides the theoretic reference to the structure optimization of sensors. With the eddy current sensor optimized above, the variety disciplinarian of magnetic induction strength, which are affected by the length, depth, buried depth and shape of the different crack are simulated. It establishes basic to detect quantitatively the crack in the actual detecting process.
Keywords eddy current testing; data acquisition; data processing; property modeling;
finite element simulation
目 录
摘 要 I
Abstract II
第1章 绪论 1
1.1 课题研究背景及意义 1
1.2 涡流检测技术 1
1.2.1 涡流检测技术特点 1
1.2.2 涡流检测技术发展 3
1.3 涡流检测国内外研究现状 5
1.3.1 信号处理技术 5
1.3.2 有限元分析技术 6
1.4 本课题的主要研究内容 7
第2章 涡流检测理论基础 9
2.1 涡流检测工作原理 9
2.1.1 涡流传感器模型描述 9
2.1.2 涡流检测等效电路 10
2.2 涡流检测理论分析 11
2.2.1 电磁渗透方程 11
2.2.2 导体中的磁场传播 12
2.2.3 导体中的涡流传播 13
2.2.4 裂纹检测 13
2.3 涡流检测影响因素 14
2.4 本章小结 15
第3章 数据采集系统的设计 16
3.1 系统总体方案设计 16
3.2 调理电路模块设计 16
3.2.1 前置放大电路设计 17
3.2.2 滤波电路设计 17
3.2.3 程控放大电路设计 18
3.3 A/D转换模块设计 19
3.4 控制模块设计 19
3.4.1 CPLD模块设计 20
3.4.2 单片机模块设计 22
3.5 PC机程序设计 23
3.6 系统实现 24
3.6.1 系统实物 24
3.6.2 测试现场 25
3.7 本章小结 26
第4章 涡流传感器静/动态特性建模方法研究 27
4.1 静/动态特性概..
涡流检测是基于电磁感应原理的一种常规无损检测方法，具有检测速度快，灵敏度高，非接触测量等特点，已经在航空、冶金、化工、机械等诸多工业领域得到了广泛应用。本文针对船舶焊缝裂纹进行检测，将涡流检测技术、数据采集技术和数据分析处理技术有机结合起来，拟开发适合在线检测的智能化涡流检测系统。本文主要研究内容包括：
1）在深入分析涡流检测基本原理的基础上，设计完成了一套以单片机和CPLD为控制核心的双通道实时涡流检测数据采集系统。该系统硬件电路包括信号放大、滤波、模数转换、CPLD、单片机及其通信电路等，软件设计主要涉及单片机C51程序、CPLD的VHDL程序、PC机VC程序等。该系统结构简单，性能稳定，能较好地满足实际需求。
2）对涡流传感器的静、动态特性进行分析是评价该传感器性能及实现在线补偿的重要环节之一。本文在了解传感器静态、动态性能指标的基础上，采用多种方法建立了涡流传感器的静、动态数学模型，并比较了相应建模效果，为下一步传感器特性进行在线补偿做了铺垫。
3）为了减小检测过程中的各种外界干扰和噪声，准确判断数据，对涡流响应信号进行了预处理，剔除数据中的无意义坏点，对数据进行平滑处理；应用小波变换理论中小波的多尺度边缘检测原理对信号进行除噪处理，极大的提高信号的信噪比，并提取了表征裂纹的特征量。
4）利用所建立的有限元模型对涡流传感器参数进行了仿真研究，分别讨论了线圈内径、外径、高度和放置方式对传感器性能的影响，为涡流传感器结构参数的优化提供了理论参考。采用优化后的涡流传感器，仿真分析了不同线圈位置，缺陷的长度、深度，埋藏深度和截面形状对检测线圈磁感应强度分量的影响，为实际检测过程中工件缺陷的定量分析奠定了基础。
关键词 涡流检测；数据采集；数据处理；特性建模；有限元仿真
Abstract
Eddy current testing based on the electromagnetic induction principle is one of the regular nondestructive testing methods. Because it has the advantages of high speed, high sensitivity and non-contact measurement, it is widely applied to the manufacture field of aviation, metallurgy, chemical and mechanical industry. In order to test weld metal cracking in ship industry, a new eddy current testing system that suits for on-line detection is developed. The intelligence system is composed of eddy current inspection theory, data acquisition and processing technology and data analysis technology. The main contents are the following:
1) Based on the theory of eddy current testing technology, a data acquisition system based on MCU and CPLD (Complex Programmable Logic Device) as core control units has been designed. The hardware circuit includes signal amplification, filtering, A/D conversion, CPLD interface and MCU communication circuit. The software design includes the C51 program, VHDL program, VC program and so on. The system has simple structure and stable performance, which can meet the requirements of testing cracks.
2) Analysis on static property and dynamic property of eddy current sensor is the important point of eva luating sensor property and realizing on-line compensation. Based on the study of static and dynamic property, the mathematic models are built by various methods, and the results are compared. This work sets the stage for compensation.
3) In order to reduce the external interference and noise and judge the data accurately, the response signal of eddy current is preprocessed and the insignificant isolated points in the data are eliminated. Wavelet multi-scale edge detection technique is used to eliminate noise, improve the signal to noise and extract characteristic quantities.
4) Eddy current sensor is simulated by finite element model, and then the influences of coil’s diameter and placing mode are discussed. So this work provides the theoretic reference to the structure optimization of sensors. With the eddy current sensor optimized above, the variety disciplinarian of magnetic induction strength, which are affected by the length, depth, buried depth and shape of the different crack are simulated. It establishes basic to detect quantitatively the crack in the actual detecting process.
Keywords eddy current testing; data acquisition; data processing; property modeling;
finite element simulation
目 录
摘 要 I
Abstract II
第1章 绪论 1
1.1 课题研究背景及意义 1
1.2 涡流检测技术 1
1.2.1 涡流检测技术特点 1
1.2.2 涡流检测技术发展 3
1.3 涡流检测国内外研究现状 5
1.3.1 信号处理技术 5
1.3.2 有限元分析技术 6
1.4 本课题的主要研究内容 7
第2章 涡流检测理论基础 9
2.1 涡流检测工作原理 9
2.1.1 涡流传感器模型描述 9
2.1.2 涡流检测等效电路 10
2.2 涡流检测理论分析 11
2.2.1 电磁渗透方程 11
2.2.2 导体中的磁场传播 12
2.2.3 导体中的涡流传播 13
2.2.4 裂纹检测 13
2.3 涡流检测影响因素 14
2.4 本章小结 15
第3章 数据采集系统的设计 16
3.1 系统总体方案设计 16
3.2 调理电路模块设计 16
3.2.1 前置放大电路设计 17
3.2.2 滤波电路设计 17
3.2.3 程控放大电路设计 18
3.3 A/D转换模块设计 19
3.4 控制模块设计 19
3.4.1 CPLD模块设计 20
3.4.2 单片机模块设计 22
3.5 PC机程序设计 23
3.6 系统实现 24
3.6.1 系统实物 24
3.6.2 测试现场 25
3.7 本章小结 26
第4章 涡流传感器静/动态特性建模方法研究 27
4.1 静/动态特性概..
