Application of Superresolution Methods for Expert Control of Cylindrical Objects

The possibility of the combined application of the extrapolation procedure to the spectrum of echo signals during construction of its AR model and of the algorithm for the production of flaw images using a multibeam method of projection in the spectral space (PSS) for testing cylindrical objects is shown. Improvement of the quality of flaw images due to a significant decrease in the “side lobe” levels in the point-spread function is demonstrated in a model experiment. These methods may prove to be especially efficient for testing metallurgical flaws in wheel pairs of rolling stock, workpieces for turbine rotors, and similar items.     

Methodological principles and techniques of ultrasonic acceptance tests of wheelset axles

The ultrasonic system designed for performing acceptance tests of wheelset axles of railway rolling stock during production with the aim of detecting metallurgical flaws and/or flaws caused by drawbacks in the manufacturing process is substantiated. The effect of the factors not regulated by the normative documents on the testing reliability, including the type and structure of probes, their location, and the surface state of a tested object, is analyzed. Recommendations for improving reliability and reproducibility of the acceptance test data on wheelset axles are formulated and confirmed experimentally.     

Ultrasonic tomography of metal structures using the digitally focused antenna array method

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.     

Experimental studies of the reflection coefficient of a film that visualizes magnetic fields in the zone of a flaw during testing of ferromagnetic objects

The character of changes in the light-reflection coefficient in the zone of indicator patterns of flaws on a magnetic-field-visualizing film was determined during magnetic testing of ferromagnetic plates. The flaw detection in specimens was performed in an applied field directed in parallel to the inspected surface. External light radiation was directed perpendicular to the specimen surface and the magnetic-field-visualizing film that were placed on it.     

金属材料超声探伤缺陷分类辅助系统的研究

针对在目前工业生产的超声检测中缺陷难以定性的问题,在现有缺陷信号处理和人工神经网络分类研究工作的基础上,基于虚拟仪器的设计思想及功能模块化的设计方法,采用PC机和数据采集卡作为硬件系统,在L abV IEW平台上建立了能对缺陷进行智能识别的系统——金属材料超声探伤缺陷分类辅助系统。系统具有采集金属材料中缺陷回波数据、降噪、特征提取和智能识别缺陷等主要功能。实验结果表明,该系统基本上能自动识别出各类缺陷。     

Nondestructive testing for flaws in the insulation of winding wires

Peculiarities of discharge that is initiated by a flawed section of wire insulation that passes through a primary gas-discharge flaw transducer have been studied. Analysis of the structure of signals has been carried out, and possible mechanism and type of discharge in the sensor have been considered. Informative zones have also been singled out in the signal structure. A technique is described for testing enamel-insulated wires for flaws. The technique makes it possible to determine the number and extent of flawed sections in an enameled wire that is fed through the system at any variable speed. Ways and means are considered for reducing the errors in evaluating the number and extent of flaws. Flow chart of a faultiness-measurement device is suggested, and the principle of its operation is described.     

Estimating the possibility of the magnetic detection of microflaws in weld seams of longitudinal electric-welded pipes manufactured by butt high-frequency welding

Fragments of longitudinal electric-welded pipes were inspected in the state after their manufacturing. The presence of flaws, like surface cracks with openings of nearly 10 μm, were detected by means of optical testing in the zone of a weld seam. It was shown that such cracks can be easily detected at the УMД-101M magnetic nondestructive testing station.     

Tribological properties of powder metallurgical tool steels used in powder compaction pressing dies

The tribological properties of two powder metallurgical (PM) tool steels, high and low nitrogen containing, are investigated by means of three different wear tests: ball‐on‐disc, rubber wheel and scratch test. The ball‐on‐disc tests showed two distinct friction curves corresponding to each material. In order to simulate the tribosystem existing in metal powder compaction dies, the rubber wheel and the scratch test were modified. The rubber wheel test was performed using ferrous powder instead of sand, and scratch testing was carried out by sliding a powder compact over the tool steels. The scratch tests indicated a higher steady‐state coefficient of friction for the low nitrogen containing PM steel as compared with the high nitrogen containing alloy. Additionally, the results from the rubber wheel tests were in agreement with industrial experiences, showing the low nitrogen containing tool steel to suffer from severe galling. Copyright © 2011 John Wiley & Sons, Ltd.     

Application of the acoustic-emission and strain-gaging methods to testing of the residual strength of airplanes

The use of acoustic-emission (AE), optical, and strain-gaging methods in cyclic tests of an airplane has been considered. During tests, before the failure of an airplane, three zones were inspected. For this purpose, saw cuts were made in the lower planes of the left and right wings and in the load-carrying structure on the right side. The AE method allowed detection of growing flaws at a 10% load relative to the rated load, when the length of a fatigue crack was at most 1 mm and was not detected via the optical method.     

Increasing the signal-to-noise ratio in ultrasonic testing of repair welds using the technology of thinned antenna arrays

To test objects of materials with a high level of structural noise, use of thinned antenna arrays (TAAs) that have a large spatial aperture and consist of a small number of elements that are positioned from one another at a distance larger than the wavelength is proposed. A TAA moves over the surface of a tested object and echo signals are recorded during transmission and reception by different pairs of piezoelectric plates. For each transmitter-receiver pair, the measured echo signals are used to reconstruct partial images, which are then coherently added together to form the final image, by the SAFT method. A procedure for calibrating each piezoelectric plate of the TAA in order to determine the coordinates of its center for efficient coherent summation of partial images has been developed. The calibration procedure reduces the requirements for the accuracy of the arrangement of the piezoelectric plates of the TAA on a prism. The use of the technology of TAAs allows one to obtain images of flaws in repair welds with a signal-to-noise ratio (SNR) that is 12 dB higher than the SNR for an image obtained using the technique for a single-element transducer. The results of testing specimens of 800 pipelines with repair welds in weld seams are presented. The efficiency of this method is shown in comparison to the method in which a single-element piezoelectric transducer is used.     

A method for improving the accuracy of evaluating the dimensions of flaws in walls of tubular elements of structures

An algorithm for evaluating the real accuracy of the basic measuring instrument (exterior or in-tube flaw detector) in measuring parameters of flaws of a particular inspected tube was proposed on condition that the basic measuring equipment has no systematic error, while a verification instrument is considered as “absolutely” precise or “reference.” A statistical method of increasing the accuracy of evaluating the dimensions of flaws in thin-walled tube elements was developed on the basis of a correlation between the dimensions of flaw parameters. It can be taken as a basis for finding real values of parameters of flaws and for performing reliable calculations of the residual strength and residual life, for scheduling optimal periods for the next inspection of pipelines, and for ranging segments of a pipeline by a risk criterion, thus providing optimal scheduling of repairs.     

Estimating the depth of surface flaws by penetrant testing

Experimental dependences are provided for the time growth of the areas of the indications of surface dead-end and through flaws with openings of 1–15 μm and depths of up to 12 mm during development under penetrant testing of stainless steel samples. A technique is proposed for estimating the depth of the surface flaws using the first derivative of the dependences 100 s after the beginning of development.     

Computer panoramic tomography for industrial application

Problems of the development and application of a high-capacity X-ray tomograph intended for testing bar-type fuel elements are considered. The tomograph created by the authors and designed for detecting and measuring flaws in welded joints in an automatic mode is briefly described, and its performance characteristics are presented. A technique for measuring flaws using reconstructed panoramic images, which is optimal for rejecting defective fuel elements under the conditions of a technological conveyor, is presented. The results of experimental tests of the tomograph involving automatic measurements of pore-type flaws in different detection modes are presented. The results of this study can be useful for other industrial applications of X-ray tomography.     

The reliability of detecting cracks during nondestructive testing of aircraft components

The reliability of detecting flaws taking their dimensions into account in the applied nondestructive testing method is evaluated on the basis of the use of two probabilistic characteristics, viz., the probability of detecting cracks of different lengths (which are usually preset) and the distribution of the lengths of the cracks that are present in a structure. A method is proposed for evaluating the a priori distribution of the lengths of cracks in a structure using the results of the performed testing.     

聚乙烯管道电熔焊接接头的超声检测

聚乙烯管连接中大量使用电熔接头,其质量的好坏直接影响管道系统的安全。分析了超声聚焦检测技术对聚乙烯管电熔接头各类缺陷的检出能力。在此基础上,运用相控阵超声技术及B扫描实时成像超声方法检测大量含缺陷接头,对比超声成像图与接头实剖图,发现该方法有较高的检测灵敏度和检出精度,可以应用于工程实践。     

Classification of flaws in ultrasonic and X-ray testing

Classification of flaws in welded joints during X-ray and ultrasonic nondestructive testing are considered. The consideration is focused on the parameters of flaws that affect the reliability of the tested item. Recommendations are made to improve identification of a flaw’s shape and type via relationships between test signatures and to assess parameters involved in calculations of the strength and service life of a tested item.     

Data-processing algorithms for automatic operation of ultrasonic systems with coherent data processing

Two algorithms for the automatic determination of flaw parameters during ultrasonic testing of welded joints with a high level of structural background noises are considered. The experimental data collected in the course of automated ultrasonic testing (AUT) using Avgur series with coherent processing of data (Avgur 4.2 and Avgur 5 systems) and the results of the assessment of nondestructive testing data are used. The first algorithm is used to identify zones where flaws may be located. This algorithm is applied after running AUT in the search mode. If the parameters of the algorithm application are selected properly, this algorithm makes it possible to determine the coordinates and the conventional length of the identified flaws. The second processing algorithm is intended to determine the flaws actual length and height. For its operations the algorithm uses the images obtained from coherent data processing. Results of testing methods for automatic (computer) determination of flaw parameters are cited. These results are obtained by the Avgur system during testing of austenite welded joints in stainless-steel pipes with a diameter of 325 mm and in perlite-steel pipes of various diameters.Translated from Defektoskopiya, Vol. 40, No. 12, 2004, pp. 3–15.Original Russian Text Copyright © 2004 by Badalyan, Vopilkin, Dolenko, Orlov, Persiantsev.This revised version was published online in April 2005 with a corrected cover date.     

Studying the correlation of the informative parameters of acoustic-emission signals with the destruction processes in specimens with welding flaws

The results of acoustic-emission (AE) testing of flaws in steel specimens during welding and subsequent loading until destruction in MTS-50 and MTS-250 electrohydraulic machines are presented. Flaws were simulated via faulty fusions or the introduction of titanium and duralumin inserts. During loading, some specimens were broken along the weld seam and the other specimens were broken in the near-seam zone. A comparative analysis of the distributions of the informative parameters of AE signals, which are recorded during different types of specimen fracture, is presented.     

Reference specimens of nonmetallic materials for penetrant nondestructive testing

A method for manufacturing reference specimens for penetrant nondestructive testing that are based on a nonmetallic material (epoxy glue) with metal foil flaws is considered.     

Diagnostics of the technical condition of pressure vessels operating under internal pressure by a thermal (thermal imaging) method

Cylindrical reservoirs made of polymer composite materials (PCMs) operating under high internal pressures are presently used in the gas, petrochemical, aerospace, and other industries. Thermal imaging is used for testing of micro- and macroflaws in vessels during pressurizing. Experiments and theoretical studies have shown that, beginning at 5–10% of the maximum acceptable pressure, thermal testing ensures reliable detection and identification of flaws with an accuracy no worse than 15%. This ensures a lower damage hazard to articles without decreased reliability of tests and leads to significant savings due to a decrease in energy consumption and working hours during testing. In addition, a lower damage hazard allows the number of repeatedly occurring flaws to be decreased.