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在管道漏磁检测中,缺陷的定量识别一直是个难题,运用有限元分析的方法,建立了漏磁场的数学模型,然后采用有限元分析软件ANSYS建立了漏磁检测装置分析的模型,并进行了二维静态情况的仿真,获得了不同缺陷所产生的漏磁信号,并把这些结果和实验结果进行了比较分析;从这些结果中可以得出了缺陷的特征与其所产生的漏磁信号的特征之间的对应关系,采用仿真的方法来研究漏磁信号的定量识别问题并取得较好的识别效果。 相似文献
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漏磁信号的有限元分析与仿真 总被引:3,自引:0,他引:3
在无损检测中,仅仅发现缺陷的存在是不够的,如果能从检测到的缺陷信号中,提取被检件上缺陷的参数,从而了解被检件受损程度,这对被检件合理使用具有重要意义。该文叙述了漏磁检测的原理,介绍了有限元分析方法在管道缺陷漏磁检测中的应用,利用ANSYS软件对不同大小形状的管道缺陷产生的漏磁信号进行仿真分析,并给出了二维仿真结果,由此推导出漏磁信号的参数与缺陷形状大小的对应关系,进而由所检测到的信号反推出被检件损伤情况,为缺陷鉴别及管道寿命评价提供依据。 相似文献
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针对工业现场使用压电超声波检测焊缝缺陷时需使用耦合剂的问题,研究了通过无须耦合剂的基于磁致伸缩电磁超声对薄钢板焊缝中缺陷进行检测的方法,并且针对电磁超声换能效率低、信号微弱的问题,通过仿真优化了回折线圈结构参数,选择了三分裂回折线圈,并探究了导波频率对缺陷检测灵敏度的影响。仿真结果表明:相比于无分裂线圈,选择三分裂回折线圈后激励信号面内位移幅值提高了94.2%,随着导波频率增加,缺陷反射回波幅值表现出先增大再减小的变化规律。实验结果表明:S0模态Lamb波垂直入射焊缝时,焊缝本身产生的回波与缺陷信号相比相对较小,缺陷检测阈值达到1 mm,缺陷定位误差小于2 mm,证明了电磁超声导波具备检测焊缝中毫米级缺陷的能力。 相似文献
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The parts ofgun often create crack when used for aperiod, in order to avoid accident caused by crack, wem ustdetect it periodically, this is very im portant for thesafely operation and the safety of the operator. Them agnetic flux leakage (M FL) detecting m ethod is verysensitive to the crack on ferrom agnetic m aterials, andwith low cost and sim ple arts and crafts. So it is verywidely used in the crack detection for gun.The principle of M FL non-destruction is as follow s.The gun ' s part… 相似文献
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ANSYS在管道漏磁检测中的应用 总被引:4,自引:0,他引:4
在介绍漏磁检测原理的基础上,详细论述了利用有限元法分析缺陷信号的方法以及利用ANSYS对漏磁信号的仿真过程和仿真结果,并对结果进行分析.仿真结果表明,这种方法不仅可以检测到缺陷的存在,而且还能根据缺陷产生的漏磁信号来鉴别缺陷大小形状,判断管道受损程度,对工件的科学合理利用有重要意义. 相似文献
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Acquisition of Weld Seam Dimensional Position Information for Arc Welding Robot Based on Vision Computing 总被引:1,自引:0,他引:1
Recognition and identification of weld environment and seam dimensional position by computer vision is a key technology for developing advanced autonomous welding robot. Aiming at requirements for recognition of weld seam image characteristics, this paper first presents an improved algorithm of subpixel edge detection based on Zernike moments. Comparing with the Ghosal’s original algorithm, the improved algorithm deals with mask effect and first derivative model on edge gradient direction so that it has the strong robust to noise, self-thinning ability and higher locating precision. An algorithm based on ZMs to extract line is also proposed, the comparative results with SHT and RHT show the method has the highest calculation speed and accuracy. The stereovision technology is developed to identify dimensional position of weld seam by computing dimensional coordinates of the weld seam. According to characteristics of weld seam, view field scope model and stereovision model based on baseline are studied and a stereo matching method is presented. In order to evaluate the algorithms and models presented in this paper, a welding robot systems with single camera fixed on the weld torch end-effector has been established for the robot to identify the dimensional position of typical weld seam by one-item and two-position method. The experiment results on S-shape and saddle-shape weld seams show that the vision computing method developed in this paper can be used for acquiring weld seam dimensional position information in welding robot system. Thus the welding path is mapped before the welding operation is executed. 相似文献
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管道腐蚀检测中新型脉冲漏磁传感器的设计与实验验证 总被引:1,自引:0,他引:1
在金属管道腐蚀检测方面,脉冲漏磁技术显示了潜在的优势.在对多种不同结构的传感器进行实验和仿真分析的基础上,提出了一种新型结构的脉冲漏磁传感器,用于带一定厚度保温层管道腐蚀缺陷的检测.该新型传感器在结构上采用传统漏磁检测的磁路设计方法,同时采用脉冲方波作为激励,这样既利用了漏磁检测聚磁效果好的优点,提高了激励场的穿透深度,又利用了脉冲激励所具有的频率成分丰富的优点,增强了激励场对保温层的穿透效果和对管道深层缺陷的检测效果.实验证明了传感器设计的正确性及有效性. 相似文献
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《Sensors and actuators. A, Physical》2006,125(2):186-191
Magnetic flux leakage (MFL) techniques have been widely used for non-intrusively inspecting steel installations by applying magnetization. In the situations where defects may take place on the near and far surfaces of the structure under inspection, current MFL techniques are unable to determine their approximate size. Consequently, an extra transducer may have to be included to provide the extra information required. This paper presents a new approach termed as pulsed magnetic flux leakage (PMFL) for crack detection and characterisation. The probe design and method are introduced. The signal features in time–frequency domains are investigated through theoretical simulations and experiments. The results show that the technique can potentially provide additional information about the defects. Lastly, potential applications are suggested. 相似文献
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Signals collected from the magnetic scans of metal-loss defects have distinct patterns. Experienced pipeline engineers are able to recognize those patterns in magnetic flux leakage (MFL) scans of pipelines, and use them to characterize defect types (e.g., corrosion, cracks, dents, etc.) and estimate their lengths and depths. This task, however, can be highly cumbersome to a human operator, because of the large amount of data to be analyzed. This paper proposes a solution to automate the analysis of MFL signals. The proposed solution uses pattern-adapted wavelets to detect and estimate the length of metal-loss defects. Once the parts of MFL signals corresponding to metal-loss defects are isolated, artificial neural networks are used to predict their depth. The proposed technique is computationally efficient, achieves high levels of accuracy, and works for a wide range of defect shapes. 相似文献
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为了可以快速地获取飞机在飞行过程中的速度、位置等信息,同时保证有较大的探测区域,设计了一种通过计算感应磁场强度分析飞机速度、位置的探测系统。建立了基于感应磁场强度反演飞机速度的数学模型,推导了探测系统的感应磁场强度表达式。仿真计算了磁场强度与探测距离、角频率的函数关系,可知探测距离的影响效果较大,角频率的影响效果较小,且感应磁场强度的量级基本符合磁力探测器的检出限要求。模拟实验通过等比例缩小实物的方法,将飞机用金属棒代替,对不同速度的金属棒进行测试,分析计算3个磁力探测器的磁场强度变化,可获得目标的速度、位置等信息,证明了系统的可行性。 相似文献
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钟映春 《计算机工程与应用》2008,44(20):226-228
自动对射线底片图像进行分析和缺陷类型识别是无损探伤研究领域的一个热点。在对焊缝射线底片进行图像去噪和图像增强的基础上,对焊缝底片图像进行二值化处理,进而提取焊缝缺陷图像及其特征,再采用决策树方法建立焊缝缺陷特征的分类规则,并用这些规则对二值化后的焊缝缺陷图像进行分类识别。实验结果表明,基于决策树方法对焊缝缺陷图像识别的准确率高,而且所表达的知识易于理解。 相似文献