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0引言
涡流探伤是铜杆线在线生产过程中进行质量监控的主要手段,探伤系统检测准确程度对生产铜杆线的质量有直接影响。涡流无损探伤系统一般由涡流探伤仪、涡流无损探头、记录装置、传动装置及磁饱和装置等组成,其中涡流无损探头作为系统的核心检测器件,必须有一套测试系统对其进行定期校准,方能保证涡流探伤系统的正常使用。 相似文献
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基于大涡模拟(Large Eddy Simulation)方法,结合高阶TCD/WENO混合格式,对2.5Ma超声速激波/边界层干扰诱导的微楔和微叶片两种微涡流发生器控制进行了数值模拟。数值结果表明:从边界层厚度与分离区大小及结构变化均说明两种涡流发生器对激波边界层分离起到明显抑制作用。对于微楔式涡流发生器,入射激波对微楔尾涡压缩作用明显,使流向涡对的卷吸加强,从而增加边界层内外流体能量交换。微叶片式涡流发生器的控制机理与微楔相似,但其涡对在尾部较远处易破裂,会影响内外流体之间的能量交换。 相似文献
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铝管蒸发器是冰箱制冷系统的重要部件,铝管腐蚀泄漏导致制冷系统不起作用。本文利用扫描电子显微镜、金相显微镜、化学成分分析和微区分析、溶出实验和应力腐蚀实验等方法研究了铝管腐蚀失效的原因和特征。铝管腐蚀方向主要是由外向内侧进行的,具有晶间腐蚀特征。微区能谱分析表明铝管腐蚀微区中铁杂质分布不均匀,且明显超标,这是铝管腐蚀的内因。防腐涂层涂刷不均匀和发泡材料的腐蚀性介质是引起腐蚀的外部条件。蒸发器生产现场的某些工装可引起铝管破损,加速腐蚀。在上述研究基础上,本文提出了质量改进措施,并取得了良好效果。 相似文献
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《理化检验(物理分册)》2001,37(7)
上海泛亚无损检测技术有限公司是由上海材料研究所原无损检测研究室改制组成。公司下属的经营部是公司的销售经营部门 ,专业经销各类进口和国产无损检测设备、器材和有关专业图书资料。经销的产品包括超声波探伤仪、X射线探伤机、γ射线探伤仪、射线探伤胶片和冲洗设备、X射线实时成象检测装置、涡流检测仪、自动涡流检测装置、磁粉探伤机、半自动磁粉探伤装置、各种磁粉和渗透探伤剂、各类测厚仪以及各类探伤试块和附件等。此外 ,公司也为企业提供探伤服务、承包探伤工程 ,帮助企业设计和建造无损检测试验室、培训无损检测人员 ,并愿与各… 相似文献
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以射流振荡技术为基础,设计了一种用于测量微通道内液体流量的射流振荡式流量计.通过对微通道射流流量计结构模型的FLUENT数值仿真,研究流体流动过程的振荡特性及振荡原理,进而优化结构参数,建立微通道内液体流速与振荡频率的特性关系.最终的仿真结果表明,射流振荡式流量计附壁稳定,切换灵敏,斯特劳哈尔数恒定,在一定程度上为微通道射流流量计的设计及优化提供了有效的途径. 相似文献
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本文通过建立以R134a为制冷剂的微通道平行流冷凝器的分布参数模型,使用交复检验非线性法对微通道冷凝器两相区的传热和压降关联式进行修正,并与无修正的仿真模拟结果、传统简单多项式拟合修正法的结果进行了比较。结果表明,运用交复检验非线性法修正的效果要优于无修正及传统简单多项式拟合法,使用前者修正后可将换热量误差减少64. 5%,均方误差控制在3%以内;制冷剂侧压降误差减少82. 05%,均方误差控制在10%以内,该方法为换热量和制冷剂侧压降的修正提供了一种预测精度更高的思路和方法。 相似文献
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针对前馈式自适应有源降噪系统次级通道在线建模问题,首先分析比较已有的在线次级通道建模方法,给出了各自的优缺点。在此基础上提出了一种基于Fx LMS算法的在线次级通道建模方法,该方法使次级通道建模步长随干扰信号和建模白噪声信号功率自适应更新,降低了初级噪声对建模的不利影响,并利用误差信号相关值和初级噪声能量来更新控制滤波器步长,有效降低了突发随机噪声对系统稳定性的影响。计算机仿真结果表明,该方法显著提高了次级通道模型的精度和系统收敛速度,取得更好的降噪效果。 相似文献
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针对传统差动式涡流探头几何尺寸大、缺陷检测灵敏度低的问题,在传统差动式涡流探头的基础上,设计了一种跑道型差动式涡流探头。它由激励线圈包裹2个尺寸相同、反向连接的感应线圈而构成。首先,利用COMSOL Multiphysics仿真软件建立了跑道型差动式涡流探头模型,比较了跑道型差动式涡流探头与传统差动式涡流探头涡流场分布的差异,并研究了在不同缺陷深度、不同扫查角度下2种差动式涡流探头的检测灵敏度。接着,制作了跑道型差动式涡流探头实物和碳钢板缺陷试件,利用试验测试的方法比较了跑道型和传统差动式涡流探头的检测灵敏度。试验结果表明,与传统差动式涡流探头相比,跑道型差动式涡流探头具有更紧凑的结构、更高的缺陷检测灵敏度。研究结果可为小尺寸、高精度差动式涡流探头的优化设计提供参考。 相似文献
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基于误差通道在线辨识的结构振动主动控制系统 总被引:2,自引:1,他引:1
提出一种新的基于误差通道在线辨识的有源控制方法,并把它应用于结构的主动控制。它能较好地消除误差通道辨识环节和主动控制环节之间的相互影响,从而提高系统的总体性能。针对一算例与前人的方法进行了比较,仿真结果表明无论在控制初始还是对误差通道参数及外扰变化的适应性,本文的方法均优于前两种方法。在此基础上,以悬臂梁为控制对象,对此方法进行结构振动主动控制的试验研究。试验结果表明该控制系统对悬臂梁的振动响应能有很好的抑制作用,说明这种基于误差通道在线辨识的主动控制方法是行之有效的。 相似文献
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S. I. Aks'onova A. P. Lyubchenko V. M. Uchanin V. Yu. Melanchuk B. V. Tykhomyrov S. I. Yavorovych 《Materials Science》2005,41(3):406-409
We describe a dynamic eddy current flaw detector for the testing of thin-walled brass tubes with rotation of the eddy current
transducer around them. We show that the eddy current method makes it possible to detect the greatest number of defective
tubes as compared with the visual and hydraulic-test methods. The productivity of the eddy current method is 8 – 10 times
as high as that of other methods. It enables one to evaluate the depths of defects and, correspondingly, the degree of their
danger by the signal amplitude of the eddy current flaw detector. We show the possibility to set an optimal reject criterion
and the corresponding level of operation of the threshold device of the flaw detector. The rejection of tubes with defects
deeper than the assigned value makes it possible to decrease the number of wrongly rejected tubes. The LEOTEST VD-5D dynamic
eddy current flaw detector was introduced in the technological process of full-scale locomotive production.
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Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 41, No. 3, pp. 109 – 111, May – June, 2005. 相似文献
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Magnetic saturation is applied to ferromagnetic tubes inspected by the encircling or inner coil because suppressing magnetic noise is important for the eddy current testing technique. Eddy current signal characteristics in magnetically saturated tubes are different from those in nonmagnetic tubes. In ferromagnetic tubes, defect signal phase angle is not useful for estimating defect depth because it does not depend on the defect depth. In this paper, numerical eddy current analysis has been done in order to explain the relationship between the defect depth and the phase angle in magnetically saturated tubes. This analysis is performed as follows: 1) The magnetic permeability near the defect is calculated as the non-linear magnetostatic problem. 2) The eddy current distribution is calculated as the linear magnetodynamic problem using the incremental permeability value calculated in step 1. The numerical analysis results reveal that the permeability around the defect remains inhomogeneous and it causes the unique eddy current characteristics. Based on these calculated results, a quantitative evaluation method of determining defect depth is proposed. After determining the defect shape by using signal characteristics obtained from the strongly magnetizing state, the defect depth can be estimated by using the signal amplitude. 相似文献
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Abstract Magnetic saturation is applied to ferromagnetic tubes inspected by the encircling or inner coil because suppressing magnetic noise is important for the eddy current testing technique. Eddy current signal characteristics in magnetically saturated tubes are different from those in nonmagnetic tubes. In ferromagnetic tubes, defect signal phase angle is not useful for estimating defect depth because it does not depend on the defect depth. In this paper, numerical eddy current analysis has been done in order to explain the relationship between the defect depth and the phase angle in magnetically saturated tubes. This analysis is performed as follows: 1) The magnetic permeability near the defect is calculated as the non-linear magnetostatic problem. 2) The eddy current distribution is calculated as the linear magnetodynamic problem using the incremental permeability value calculated in step 1. The numerical analysis results reveal that the permeability around the defect remains inhomogeneous and it causes the unique eddy current characteristics. Based on these calculated results, a quantitative evaluation method of determining defect depth is proposed. After determining the defect shape by using signal characteristics obtained from the strongly magnetizing state, the defect depth can be estimated by using the signal amplitude. 相似文献
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织构广泛存在于铝合金制品中,并影响着材料的一系列性能,包括强度、延展性、成形性和腐蚀性等。介绍了目前织构的一般测试分析方法,主要阐述了铝合金制造加工过程中产生的各种类型织构,如铸造织构、变形织构和再结晶织构等以及它们的演变规律,分析了铝合金加工工艺对材料最终的织构成分及织构强弱的影响,并揭示了厚板铝合金轧制和铝合金的搅拌摩擦焊接过程中产生的不均匀分布织构,以及其对材料性能的影响。最后介绍了铝合金织构的应用情况,并对铝合金织构的研究前景进行了展望,提出了在线织构检测技术,将是未来铝合金织构测试分析的主要发展方向之一。 相似文献
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Theodoulidis 《Research in Nondestructive Evaluation》2002,14(2):111-126
By utilizing the second-order vector potential formulation we solve the eddy current problem of a coil inside a conductive
tube and in an offset position to it. The study focuses on the derivation of a closed-form expression for the impedance change
of the coil, which is used to calculate the signal produced by wobble in eddy current testing of tubes with bobbin coils. 相似文献