共查询到20条相似文献,搜索用时 78 毫秒
1.
V. K. Kachanov I. V. Sokolov D. V. Timofeev M. V. Turkin E. V. Shalimova 《Russian Journal of Nondestructive Testing》2010,46(5):342-349
The features of algorithms for identifying the configurations of reflecting objects (points, spheres, planes, cylinders, etc.)
in ultrasonic tomography of complexly structured concrete products are considered. The results of a practical solution to
the problem of recognizing a pattern and determining the coordinates of a flat reflector using ultrasonic phased antenna arrays
are presented for the example of applying the algorithm of focusing to a plane. 相似文献
2.
The use of complexly modulated signals during ultrasonic testing of articles with high integral ultrasonic attenuation is substantiated. On the basis of concepts of the optimal-filtering theory, phase-manipulated and frequency-modulated signals most suitable for ultrasonic testing are chosen and the main characteristics of various complexly modulated signals are analyzed. The advantage of using phase-manipulated and frequency-modulated signals in ultrasonic flaw detection for ensuring a high testing resolution and a high sensitivity is shown. It has been revealed that the application of state-of-the-art circuitry components allows the use of various properties of complexly modulated signals and creation of new ultrasonic methods and devices on this basis. 相似文献
3.
Comparison of systems for ultrasonic nondestructive testing using antenna arrays or phased antenna arrays 总被引:1,自引:0,他引:1
E. G. Bazulin 《Russian Journal of Nondestructive Testing》2013,49(7):404-423
This paper considers the features of forming the images of reflectors using phased antenna array technology and the images obtained by the C-SAFT method by echo signals measured in by double-scanning mode. It is shown that in some cases the images obtained by the phased antenna array technology are less informative, while the images obtained by the C-SAFT method have a higher frontal resolution over the entire area of image restoration; the partial images restored at different positions of the antenna array can be coherently combined to obtain a high and homogeneous resolution throughout the entire volume of thickwalled articles and increasing the signal/noise ratio. For the sake of brevity, the registration of echo signals in the double-scanning mode and restoration of the images of reflectors by the C-SAFT method will be called digital focusing by an antenna array (DFA). The ability to restore the partial images of reflectors by once measured echo signals according to many acoustic schemes with their consequent combination into one high-quality image should provide reliable automation of the process of recognition and dimensioning of scatterers. Another advantage of the images obtained by the C-SAFT method with three-dimensional focusing is the possibility of restoring images in the same coordinate system when using antenna arrays on prisms of different configurations. This facilitates the joint analysis of the images. Speeds of forming the images by the technology of phased-antenna arrays and the images obtained by the C-SAFT method are comparable. If the testing technique is based on the use of nonlinear effects, then in this case PA flaw detectors have a distinct advantage over DFA flaw detectors. However, within the framework of linear acoustics, PA flaw detectors have no fundamental advantages over DFA flaw detectors. It is fairer to say that PA flaw detectors have drawbacks. This article shows images that illustrate the features of the images that were obtained by PA and DFA flaw detectors. 相似文献
4.
Russian Journal of Nondestructive Testing - In ultrasonic testing with antenna arrays, the measured echo signals may contain interference echo signals that, after reconstructing the image of... 相似文献
5.
E. G. Bazulin 《Russian Journal of Nondestructive Testing》2017,53(3):175-189
The reliability of ultrasonic nondestructive testing can be improved by acquiring reflector images that can be used to solve the defectometry problem, that is, to determine the type, size, and coordinates of a reflector deep in the sample. Welded pipelines with a diameter of 840 mm (Du800 type) are used at nuclear power facilities in Russia; ultrasonic testing of these pipelines is thus a topical problem. In model experiments, echo signals were registered by two antenna arrays, situated on the opposite sides of a welded joint (the N- and P-sides). The arrays performed scanning along and across the welded joint. The following techniques were used to reconstruct reflector images by the DFA method in a homogeneous isotropic medium: registering echo signals for all emission–reception combinations of elements in the two antenna arrays with the aim of merging partial images into a single image by different methods; reconstructing images on different acoustic schemes with allowance for wave-type transformation; and registering echo signals in a triple-scanning mode with subsequent coherent summation of partial images. It has been shown that the above techniques are insufficient for producing high-quality images. 相似文献
6.
These and subsequent articles present the results of the studies of interference resistant methods and devices for ultrasonic testing of extended items made of complexly structured materials. The presented results are based on the radio-engineering R &; D that have been conducted for over 30 years by the Department of Electronic Devices of the Moscow Power Engineering Institute. The studies are concurrently focused on the development of methods for separating echo signals from white and structural noise, on the application of complexly modulated signals, on the development of spatial and temporal methods for processing signals, on the development of broadband mosaic transducers, and on the design of multifunctional devices for ultrasonic testing. The necessity of such a comprehensive approach to ultrasonic testing is substantiated in this article by analysis of the problems of ultrasonic testing of complexly structured items with strong integral attenuation of ultrasound. 相似文献
7.
V. K. Kachanov V. G. Kartashev I. V. Sokolov L. V. Voronkova A. B. Rodin D. V. Timofeev 《Russian Journal of Nondestructive Testing》2010,46(4):235-248
The main principles of spatiotemporal processing of signals during ultrasonic testing of articles manufactured from complexly
structured materials with high signal attenuation are considered. Features of ultrasonic low-frequency testing limiting the
application of the simplest algorithms for spatiotemporal signal processing in both ultrasonic flaw detection and ultrasonic
tomography of articles manufactured from complexly structured materials are analyzed. 相似文献
8.
E. G. Bazulin S. A. Kokolev A. S. Golubev 《Russian Journal of Nondestructive Testing》2009,45(2):86-97
The prospects for applying the double-scanning mode in ultrasonic nondestructive testing for recording echo signals are considered. A variant of implementing the double-scanning mode using a phased antenna array is proposed. Algorithms for reconstructing flaw images by the method of projection in the spectral space and the combined SAFT (C-SAFT) method are presented. It is shown that, to obtain high-quality flaw images, the ultrasound propagation velocity in a tested object must be known to within a high accuracy (at least 0.5%). The results of numerical and model experiments in which images were obtained by these methods are presented. 相似文献
9.
Physical principles and algorithms for reconstructing images of the inner structure of an object made of a solid material
are considered. These are based on the pulsed echo method of ultrasonic testing using multielement antenna arrays focused
on each point of the visualized region of the object by spatiotemporal processing of signals from a combination sounding of
the object by all possible pairs of the antenna array. Substantial improvement of the image during testing of a plane-parallel
object is obtained by using signals that are multiply reflected from the object boundaries; the use of different algorithms
of image reconstruction is expedient for different types of discontinuity flaws. 相似文献
10.
When running ultrasonic testing, it is possible to analyze reflector images that have been restored by the method of digital focusing with an antenna (DFA). To improve the quality of the reflector images, one can use a coherence factor (CF) or a sign coherence factor (SCF) obtained from the calculated delay times instead of counting echo signals. The images obtained with the calculation of the coherence factor make it possible to increase the signal-to-noise ratio and front resolution. It has been demonstrated by numerical and model experiments that reconstructing the CF- and SCF-images of reflectors is efficient when registering echo signals by both ordinary and thinned (TAA) antenna arrays, in which the distance between neighboring elements is much greater than the wavelength. 相似文献
11.
A technique is proposed for measuring the speed of longitudinal ultrasonic waves in a homogeneous welded joint, based on comparing measured and computed echo signals reflected from the bottom of a test object when using two antenna arrays mounted on prisms and operating in the double scanning mode. The effect of errors in setting the values of such parameters as the distance between the antenna arrays, test-object thickness, and others on the accuracy of calculating the wave velocity in the weld has been analyzed. Results of numerical and model experiments on calculating the wave velocity in the welded joint are presented. In a model experiment, the technique has made it possible to measure the speed of longitudinal waves in the weld model with an error of less than 0.7%. The method can be used to find the initial approximation in a nonlinear inverse problem of tomographic inspection of welded joints in the wave approximation. 相似文献
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13.
V. K. Kachanov I. V. Sokolov R. V. Kontsov A. A. Sinitsyn 《Russian Journal of Nondestructive Testing》2017,53(1):23-31
A reference-free method is considered for concurrent measurement of the speed of ultrasonic vibrations and the thickness of concrete constructional products with ultrasonic antenna arrays that use the “focusing to a plane” algorithm. 相似文献
14.
随着洲际弹道导弹、潜射弹道导弹、多弹头分导再入式导弹等进攻性武器和各种卫星的发展,对覆盖距离远、分辨率高、跟踪目标多的多功能探测系统装备——大型相控阵雷达的需求日益增加。近年来,大型相控阵雷达得到了长足的发展,远程预警雷达、远程相控阵雷达、远程防空监测雷达等均已完成阵地布设。不同的天线阵面安装结构形式对雷达装备的架设、阵面精度的控制带来了不同的影响。文中通过对比2部大型固定式相控阵天线阵面安装与阵面精度控制过程,分析了过渡骨架和调整机构2种连接结构形式对天线阵面的安装与精度控制的影响,阐述了两者的优劣之处,对今后大型相控阵雷达的高效、低成本研制和部署具有借鉴意义。 相似文献
15.
为了满足星载有源相控阵天线对轻量化以及承载、热控等多功能一体化的迫切需求,文中开展了轻质多功能结构相控阵天线的设计理论、制备工艺、控温特性和力学性能等研究,提出了一种基于多功能结构的星载有源相控阵天线一体化设计技术,利用轻质多功能复合安装板结构,合并平面正交一体桁架热管,在内部空间嵌埋有源功能模块,融合低剖面辐射阵面形成天线功能,制备了集控温、承载、电磁辐射于一体的多功能结构的轻质相控阵天线,并对多功能结构天线子阵进行了一体化设计和验证。结果表明,多功能结构天线系统布局改善了微波部件互联的性能,提高了有源阵列的散热和辐射效率以及系统性能,显著减小了天线阵列的剖面,大幅降低了有源阵列天线的重量。 相似文献
16.
V. K. Kachanov I. V. Sokolov M. V. Turkin D. V. Timofeev M. B. Fedorov 《Russian Journal of Nondestructive Testing》2009,45(12):838-849
Questions of using various techniques for processing echo signals in ultrasonic tomography instruments for extended complexly
structured concrete articles are considered. Various algorithms are discussed for constructing tomograms of tested articles,
techniques for radio engineering processing of ultrasonic signals, and different variants of nonlinear image transformations
intended for increasing the signal-to-structural noise ratio and improving image quality. 相似文献
17.
V. K. Kachanov I. V. Sokolov A. B. Rodin L. V. Voronkova 《Russian Journal of Nondestructive Testing》2008,44(11):733-746
Problems of ultrasonic noise-immune testing of complexly structured cast-iron articles are considered. It is shown that the extraction of informative echo signals from noise and interference requires, in addition to the fulfillment of optimal signal-filtering conditions, the use of flexible multifunctional equipment for ultrasonic testing that allows formation of various signals, flexible variation of their parameters, and application of numerous radio-engineering operations to signals for adapting the parameters of the instrumentation to the characteristics of a tested object. 相似文献
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基于超声相控阵的主动结构健康监测是飞行器结构健康监测领域一个新的发展方向,也是当前研究的难点之一,超声相控阵结构健康监测在国内还处于起步阶段。在已有应用超声相控阵技术对单损伤定位的基础上,进一步研究飞行器结构中多损伤的监测。通过控制信号的延时,进而控制波束指向,实现对结构的多方位、多损伤扫描。在铝板上进行了实验研究,通过对比不同角度延时前后的损伤散射信号及其合成信号,验证了超声相控阵对多损伤信号的延时叠加能够有效地提高多损伤信号的能量,同时减少非损伤处的能量,从而增强了信号的信噪比,并且对多损伤识别具有较高精度 相似文献