Discussion on the Daily Application of GCT-8C Digital Rail Flaw Detector in Rail Flaw Detection

Operation of railway rolling stock is accompanied by high costs of maintaining its operating condition throughout the entire period of operation. To improve the operation efficiency of rolling stock, methods and diagnostics tools have been developed, which are used both in its manufacture and in carrying out maintenance and repairs, and as an independent technological process. Diagnostics allows to increase the availability factor and the probability of uptime of the rolling stock, reduce the complexity and cost of periodic maintenance of its nodes. The article proposes a new integrated method for estimating discontinuities in parts and units of railway rolling stock according to the amplitude — distance — diameter diagrams by the standardless method with the possibility of determining the type of discontinuity by the dual-frequency method of flaw-detection with a manual ultrasonic testing with a single-channel ultrasonic flaw detector. Developed method is most relevant in the control of cast parts of railway rolling stock, since castings can be equally likely to contain bulk (pores, shells, nonmetallic inclusions, etc.) and planar discontinuities (cracks of different origin; flocks; segregations that lead to violation continuity, etc.). Proposed method allows estimating the discontinuity by comparing the amplitude of the echo signal from it with the corresponding type of tuning reflector: if the discontinuity is planar as a result of using the two-frequency flaw-detection method, the comparison is carried out with the amplitude of the flat-bottomed cylindrical reflector; if the discontinuity is volumetric, then the comparison is made with the amplitude from the spherical reflector. The article describes the algorithm that was developed to automate the calculation of the parameters of the amplitude — distance — diameter diagram, the parameters of the use of the two-frequency method, and also the estimation of the detected discontinuities, and, based on it, the NDTRT-25 software that allows ensuring the convenience of the operator-diagnostician.

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APPLICATION OF INCLINED LONGITUDINAL ULTRASONIC WAVES TO IMPROVE THE EFFICIENCY OF RAIL FLAW DETECTION

Kontrol Diagnostika ◽

10.14489/td.2021.08.pp.004-013 ◽

2021 ◽

pp. 4-13

Author(s):

A. A. Markov ◽

V. V. Mosyagin ◽

S. L. Molotkov ◽

G. A. Ivanov

Keyword(s):

Mathematical Modeling ◽

Ultrasonic Testing ◽

Flaw Detection ◽

Flaw Detector ◽

Ultrasonic Waves ◽

Shadow Method ◽

Additional Information ◽

Location Depth ◽

Definition Of ◽

Longitudinal Ultrasonic Waves

The article is devoted to the question of rail ultrasonic testing confidence. At present there is a range of flaw orientation angles in within which the testing is absent and, therefore such flaws can be lost. To except this drawback the current sound testing scheme in flaw detector railcars is to be supplemented with inclined probes exciting longitudinal wave. Experimental checks using echomethod showed the good results on an October railway section with flaw models and on a loaded Zabaycalskaya railway section. The next step was idea of mirror-shadow method using as well as echomethod by turning of probes towards each other. Envelope analysis of bottom signals allows receiving additional information about flaws: location depth of its center and form. But using of pair of probes was not enough for unambiguous definition of other geometric flaws characteristics. That is why the bottom signal envelope of straight probe was to be analyzed additionally. A mobile (as well removable) searching system of rail checking means has such probe as a rule. In the process of writing the article previously obtained formulas to calculate depth, inclination angle and plane size of revealed flaw were modified. Values changing during testing process are absent now. Algorithm of flaws identification on the basis of bottom signals envelope is given. The approach is confirmed by mathematical modeling in CIVA-UT.

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Effective Method of Correction of Acoustic Losses in a Contact Layer at Ultrasonic Flaw Detection

NDT World ◽

10.12737/12570 ◽

2015 ◽

Vol 18 (3) ◽

pp. 45-46

Author(s):

Щербинский ◽

Viktor Shcherbinskii

Keyword(s):

Surface Roughness ◽

Incident Angle ◽

Flaw Detection ◽

Contact Layer ◽

Gain Factor ◽

Flaw Detector ◽

Real Surface ◽

Ultrasonic Flaw Detection ◽

Ultrasonic Flaw ◽

Acoustic Losses

At ultrasonic flaw detection it is necessary to take into account an acoustic loss in a contact layer, especially for products with a statistically rough surface (roughness, waviness). Using samples with the surface identical to the product’s one is the most desirable variant, it is regulated in many techniques, but in practice in vast majority of cases this is not so. Measurements with profilographs or profilometers are taken on a very small area (less than the piezoelectric transducer size) and cannot give an estimation of a real contact layer condition under the whole transducer area. For integral roughness estimation in “CNIITMASH” the capacitance-type sensor DShV has been developed. The sensor is compatible with flaw detectors of any type; it forms a service signal with amplitude that is inversely proportional to a roughness height. Within a frequency rate of 1.8–5 MHz and an incident angle rate of 35–70° the correlation between sensor readings and acoustic losses in a contact layer has been ascertained; a general dependence for them has been obtained, a heuristic equation has been derived and nomograms for piezoelectric transducers of different manufacturers on the sample basis of 123 measurements have been plotted. As a result the new technique of ultrasonic flaw detection has been developed that includes: estimation of tested object real surface roughness with the DShV sensor, flaw detector sensitivity adjustment using a sample with a smooth surface, a gain factor correction by the value taken from a nomogram or calculated on the formula basis. Equivalent defect area should also be measured according to the algorithm described. This technique on principle increases repeatability and reliability of flaw detection results.

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An Algorithm for Correcting Levels of Useful Signals on Interpretation of Eddy-Current Defectograms

Modeling and Analysis of Information Systems ◽

10.18255/1818-1015-2021-1-74-88 ◽

2021 ◽

Vol 28 (1) ◽

pp. 74-88

Author(s):

Egor V. Kuzmin ◽

Oleg E. Gorbunov ◽

Petr O. Plotnikov ◽

Vadim A. Tyukin ◽

Vladimir A. Bashkin

Keyword(s):

Eddy Current ◽

Traffic Safety ◽

Surface Defects ◽

Flaw Detection ◽

Flaw Detector ◽

Current Data ◽

Detection Methods ◽

Structural Elements ◽

Actual Problem ◽

Threshold Levels

To ensure traffic safety of railway transport, non-destructive tests of rails are regularly carried out by using various approaches and methods, including eddy-current flaw detection methods. An automatic analysis of large data sets (defectograms) that come from the corresponding equipment is an actual problem. The analysis means a process of determining the presence of defective sections along with identifying structural elements of railway tracks in defectograms. This article continues the cycle of works devoted to the problem of automatic recognizing images of defects and structural elements of rails in eddy-current defectograms. In the process of forming these images, only useful signals are taken into account, the threshold levels of amplitudes of which are determined automatically from eddy-current data. The previously used algorithm for finding threshold levels was focused on situations in which the vast majority of signals coming from the flaw detector is a rail noise. A signal is considered useful and is subject to further analysis if its amplitude is twice the corresponding noise threshold. The article is devoted to the problem of correcting threshold levels, taking into account the need to identify extensive surface defects of rails. An algorithm is proposed for finding the values of threshold levels of rail noise amplitudes with their subsequent correction in the case of a large number of useful signals from extensive defects. Examples of the algorithm’s operation on real eddy-current data are given.

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Experimental study and application of magnetic bridge double-loop main flux detection method

Insight - Non-Destructive Testing and Condition Monitoring ◽

10.1784/insi.2020.62.2.98 ◽

2020 ◽

Vol 62 (2) ◽

pp. 98-103

Author(s):

Jie Tian ◽

Pu-Fan Zhu ◽

Yang-Yang Wang ◽

Hong-Fei Guo

Keyword(s):

Magnetic Field ◽

Field Experiments ◽

Detection Method ◽

Flaw Detection ◽

Wire Rope ◽

Flaw Detector ◽

Double Loop ◽

Destructive Testing ◽

Wide Range ◽

Non Destructive

In this study, to perform online non-destructive testing (NDT) of mine wire rope damage and achieve effective and accurate flaw detection results, a magnetic bridge double-loop main flux detection method was proposed and the testing equipment was developed. The flaw detection magnetic field was simulated using a Maxwell module. The magnetic field intensity distribution and the vector direction were compared and then analysed. The practicality and feasibility of the detection method were verified by field experiments. The results show that the magnetic bridge double-loop main flux detection method is highly practicable and produces highly accurate test results. The mine wire rope non-destructive flaw detector developed using this method presents a stable detection signal and an obvious damage characteristic signal, which is more consistent with the requirements of wire rope damage detection under various working conditions. This technology has a wide range of applications.

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Environmental Monitoring and Evaluation of the X-Ray Field Flaw Inspection Workplace in a Factory Building

E3S Web of Conferences ◽

10.1051/e3sconf/201913101058 ◽

2019 ◽

Vol 131 ◽

pp. 01058

Author(s):

Qing Li ◽

Wei Xie ◽

Hong You ◽

Xiaohua Qiu ◽

Quan Guo ◽

...

Keyword(s):

Flaw Detection ◽

Monitoring And Evaluation ◽

Steel Tube ◽

Flaw Detector ◽

Radiation Environment ◽

Main Beam ◽

X Ray ◽

Tube Current ◽

Effective Doses ◽

Factory Building

The surrounding radiation environment of the field flaw detection workplace has been theoretically calculated and monitored on site when an industrial X-ray flaw detector in a factory building is operated during the field flaw detection. The results show that when 5mA tube current and 250 kV tube voltage penetrate the steel tube at the thickness of 16mm twice, the calculated value of the air kerma rate at the inspection point is basically consistent with the measured value. Additionally, the boundary of the controlled area and the supervised area corresponded to the measured value along the main beam direction belongs to the wall in the east of the workshop. The calculated distances of the leaking beam corresponding to the boundary of the controlled area and the supervised area of the calculated value should be 19m and 58m, respectively. The minimum and maximum distances of the controlled area of the measured value are 13m and 17m, respectively; while the maximum and minimum distances of the supervised area of the measured value are 31m and 36m, respectively, both areas are within the workshop. Meanwhile, annual effective doses that might be accepted by professionals and the public have been estimated.

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Crack Visualization and Dimensioning by Shadow Method at Refining Ultrasonic Inspection

NDT World ◽

10.12737/1609-3178-2020-74-76 ◽

2020 ◽

pp. 74-76

Author(s):

Anatoliy Markov ◽

Vladimir Mosyagin

Keyword(s):

Measurement Errors ◽

Ultrasonic Inspection ◽

Flaw Detection ◽

Digital Signal ◽

Flaw Detector ◽

Layer By Layer ◽

Shadow Method ◽

Transverse Cracks ◽

Simple Method ◽

Surface Damages

Principles and results of application of specially designed ultrasonic flaw detector for detection and evaluation of parameters of transverse cracks, including under surface damages of rail head, are considered. Using a fairly simple method of multichannel shadow method of ultrasonic inspection and special algorithms for digital signal processing, a flaw detector scanner was developed and introduced, which allows layer-by-layer scanning of a defective section of the rail to visualize a defect in three orthogonal planes. Multiple comparisons of the obtained flaw detection images with the results of forced dolomes show that the measurement errors of the proposed method do not exceed 15%, which is a very high indicator for practice. Proven principles are recommended for use in other industries.

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