Results Of Flaw Detection Research Articles

Innovative methodology for predicting pipe thickness loss based on electromagnetic flaw detection results

The paper proposes an innovative approach to forecasting based on the results of electromagnetic flaw detection to determine maximum pipe thickness losses over 10-m intervals of the immersion depth of the lower part of a pipe into a well. The main model uses rank transformation applied to a fuzzy regression model with fuzzy input variables and fuzzy output. The input variables include the main parameters of the reservoir in the well (temperature, density, and dynamic viscosity of the hydrocarbon mixture), while the output variable is the maximum loss of pipe thickness in the above–mentioned immersion intervals of the lower part of the pipe. The error of the output forecasts is determined using a numerical procedure to estimate the difference between fuzzy numbers. The forecasting is performed using a sliding method that combines rank fuzzy regression with clear nonlinear regression until the prediction error reaches the specified threshold value. The use of fuzzy regression with fuzzy input and output makes it possible to assess the impact of reservoir parameters on the condition of pipes and the potential for emissions and critical situations. Keywords: Fuzzy LR-type numbers; rank transformation; fuzzy regression; electromagnetic flaw detection; fuzzy outliers; sliding prediction; membership function; pipe thickness loss.

Inspection of thick composites: a comparative study between microwaves, X-ray computed tomography and ultrasonic testing

ABSTRACT Inspection of thick and low-density multilayer composite structures is of paramount importance. X-ray computed tomography (CT) and phased array ultrasonic testing (PAUT) are widely employed modalities for non-destructive testing (NDT) of these composites. Owing to low density of constituent materials typically utilised to construct composites and rich wave scattering within their structures, inspecting them using X-ray CT and PAUT does not always yield acceptable flaw detection results. On the other hand, microwave NDT techniques have shown to be particularly suitable for inspecting thick multilayer non-carbon-based composites. However, the relative performance of emerging microwave NDT techniques and the widely accepted X-ray CT and PAUT is yet to be established. This paper provides first-of-its-kind experimental comparison between microwave, X-ray CT, and PAUT on a comprehensive set of thick composite samples with different defect types. It is demonstrated herein that microwave NDT performed on par with X-ray CT in terms of defect detection capability (qualitatively and quantitatively), and in many cases outperformed PAUT. A detailed summary overviewing the performance, advantages and shortcomings of each method for particualr defect types is included which disseminates new knowledge to benefit practitioners and researchers alike.

Research on the Recognition Method of the Axle End Mark of a Train Wheelset Based on Machine Vision

Whether the wheelset of a high-speed train has defects such as cracks is very important to the safety of high-speed trains. Hence, the wheelset must be regularly inspected for flaws. For flaw detection of a wheelset, it is necessary to record the axle end information of the wheelset to correlate with the flaw detection results. To quickly and accurately identify the axle end mark of the wheelset, an automatic identification method based on machine vision is proposed. Our method identifies seven types of marks on the axle end, including the smelting number, steel grade number, unit number, sequence number, year and month, axle type mark, and the azimuth mark. Using the established automatic identification method of axle end marks, based on Retinex theory, an improved dual-core Laplacian combined with Gaussian filtering operation is proposed to solve the problem of the low contrast of the wheelset axle end image. An improved image tilt correction algorithm based on the combination of Hough circle detection and bilinear interpolation is proposed, which solves the angle tilt problem of the target character area of the axis end image. To handle the various types of axis end markers and the small amount of data, a retraining method to improve recognition accuracy is proposed. This method first uses Chi_Sim as the basic font for training and then retrains based on the trained font. Finally, Tesseract-OCR is used to improve the accuracy of the recognition results. Experiments are carried out by developing an automatic recognition program for axle end marks. The results show that the proposed method can effectively identify and classify seven-character types, and the recognition accuracy reaches 96.88% while the recognition time of each image is 5.88 s.

Results of flaw detection of parts of the «shaft - pinion bushing» connection of agricultural machinery reducers

The article has devoted to solving an urgent problem related to the fault detection of the main parts of gearboxes. A study of the dimensions of new and worn parts, forming the connection «shaft - pinion bushing» Ø4ON7/k6 in the gearboxes of agricultural machines had carried out. It was found that the defect in size is 12.45 %, and the defect in shaft size is 8.69 %. It had found that the greatest wear of the holes when reaching 0.082 mm, about 19 % of the gears must be replaced due to the excess of the inner diameter, the shafts wear up to 0.12 mm and about 23 % of the shafts have rejected. It has shown that a transitional fit is assigned in the new joint, as evidenced by the presence of both clearances and interferences, and interferences predominate. The defect to the left of the span of a fit is 0.91 % and to the right is 0.47 %. This indicates that all new holes and shafts can be allowed for assembly, including those provided by defect, but as a result, there will be practically no defect in the joints. When joints have formed from worn parts, above 25 % of rejects at the maximum clearance, therefore, flaw detection and complete control in this case are necessary.

Large Eddy Simulation of Multi-Phase Flow and Slag Entrapment in Molds with Different Widths

Slag entrapment is a critical problem that affects the quality of steel. In this work, a three-dimensional model is established to simulate the slag entrapment phenomenon, mainly focusing on the slag entrapment phenomenon at the interface between slag and steel in molds with different widths. The large eddy simulation (LES) model and discrete particle model (DPM) are used to simulate the movements of bubbles. The interactions between phases involve two-way coupling. The accuracy of our mathematical model is validated by comparing slag–metal interface fluctuations with practical measurements. The results reveal that the average interface velocity and transverse velocity decrease as the mold width increases, however, they cannot represent the severity of slag entrapment at the interface between slag and steel. Due to the influence of bubble motion behavior, the maximum interface velocity increases with mold width and causes slag entrapment readily, which can reflect the severity of slag entrapment. On this basis, by monitoring the change of impact depths in different molds, a new dimensionless number “C” is found to reveal the severity of slag entrapment at the interface between slag and steel. The results show that the criterion number C increases with mold width, which is consistent with the results of flaw detection. Therefore, criterion number C can be used to reflect the severity of slag entrapment in different molds.

Influence of measurement error for the results of defection of parts hole-type

Technological processes of repair production for a number of objective and subjective reasons do not provide the required reliability of equipment after repair. It has been shown that the most important process for incoming inspection of worn parts is fault detection. It is shown that the control process during flaw detection occurs not at the edges of the scattering zone, as it happens in mechanical engineering, but in the center. Features of formation of control errors of the 1st and 2nd kind during flaw detection of hole-type parts in repair production are considered. A new approach is proposed to assess the influence of measuring instrument error on the results of flaw detection of hole-type parts. this approach consists in developing a calculation method and plotting the dependences of calibration parameters for flaw detection of parts. Based on the proposed approach, the distribution of sorting parameters for hole-type parts by groups during defect detection is determined. The results were analyzed.

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

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.

Эффективный метод учета потерь в контактном слое при ультразвуковой дефектоскопии

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.

A multiscale flaw detection algorithm based on XFEM

SUMMARYWe present a novel multiscale algorithm for nondestructive detection of multiple flaws in structures, within an inverse problem type setting. The key idea is to apply a two‐step optimization scheme, where first rough flaw locations are quickly determined, and then, fine tuning is applied in these localized subdomains to obtain global convergence to the true flaws.The two‐step framework combines the strengths of heuristic and gradient‐based optimization methods. The first phase employs a discrete‐type optimization in which the optimizer is limited to specific flaw locations and shapes, thus converting a continuous optimization problem in the entire domain into a coarse discrete optimization problem with limited number of choices. To this end, we develop a special algorithm called discrete artificial bee colony. The second phase employs a gradient‐based optimization of the Broyden–Fletcher–Goldfarb–Shanno type on local well‐defined and bounded subdomains determined in the previous phase. A semi‐analytical approach is developed to compute the stiffness derivative associated with the evaluation of objective function gradients.The eXtended FEM (XFEM), with both circular and elliptical void enrichment functions, is used to solve the forward problem and alleviate the costly remeshing of every candidate flaw, in both optimization steps.The multiscale algorithm is tested on several benchmark examples to identify various numbers and types of flaws with arbitrary shapes and sizes (e.g., cracks, voids, and their combination), without knowing the number of flaws beforehand. We study the size effect of the pseudo grids in the first optimization step and consider the effect of modeling error and measurement noise. The results are compared with the previous work that employed a single continuous optimization scheme (XFEM–genetic algorithm and XFEM–artificial bee colony methods). We illustrate that the proposed methodology is robust, yields accurate flaw detection results, and in particular leads to significant improvements in convergence rates compared with the previous work. Copyright © 2014 John Wiley & Sons, Ltd.

On the analysis of in-tube flaw-detection results characterizing the state of a trunk gas pipeline with corrosion flaws

On the analysis of in-tube flaw-detection results characterizing the state of a trunk gas pipeline with corrosion flaws

On the analysis of in-tube flaw-detection results characterizing the state of a trunk gas pipeline with corrosion flaws

Today, results of in-tube flaw detection (ITFD) are used mainly to solve routine problems of the provision of service reliability of operating gas pipelines (via the removal or selective repair of damaged pipes). However, the task of nondestructive testing consists in not only the detection of flaws but also in the determination of the principal causes of their appearance. This calls for the use of quantitative indexes of flaw parameters for estimating steady tendencies toward the development of damaging, determining the most essential causes of the formation of detected flaws, and predicting possible dynamics of their propagation as the time of operation of a trunk gas pipeline (TGP) system increases. These tasks can be solved based on an analysis of primary results of ITFD by selecting and using steady quantitative indexes of the total damaging using statistical techniques.

Treatment of false calls in evaluating nondestructive inspection proficiency

A test designed to evaluate nondestructive flaw detection proficiency by ultrasonic and eddy current methods has been conducted. Test data for each participant are reduced to contingency table format, and analysis of these tables via traditional measures of association is used to rank individual performances. The presence of false calls in an inspection record introduces a random inflation in flaw detection results. Measures are required which compensate for that fact. Proficiency rankings based on two such measures, Somers'd coefficient and the mean square contingency coefficient, show reasonable consistency with intuition-based rankings by experienced observers. Finally, a weighted generalization of Somers'sd is suggested, although optimal selection of weights remains an open problem.

Ultrasonic Flaw Detection

PURPOSE: To facilitate quantitative judgement on the results of flaw detection with a higher measuring accuracy of in the detection capacity of internal defects of material to be detected, by keeping apparent dimensions of ultrasonic vibrators almost constant as viewed from the material being detected regardless of the angle of refraction of an ultrasonic beam. CONSTITUTION: When emitted with the ultrasonic beam deflection angle θ from ultrasonic vibrators 2lW2m located almost at the center of an array type probe, an ultrasonic beam 3 is refracted on the boundary 8 between a shoe 9 and material 4 to be detected to propagate through the material 4 being detected at the angle θ of refraction. At this point, when the wedge angle of the shoe 9 set at α, the angle of incidence of the ultrasonic beam emitted to the shoe 9 at the angle θ of deflection with respect to the boundary plane is given by α=ϕ+γ. Thus, a signal controller calculates the delay time in the transmission and reception when ultrasonic waves are each transmitted and received by the vibrators 2 at each deflection scan angle of the ultrasonic beam to set transmission and reception delay data to a transmission/reception setter each time the scan angle is altered. Therefore, the transmission and the reception of the ultrasonic beam can be done at a specified angle of refraction, thereby enabling the detection kept of flaws with the beam 3 to the material 4 being detected constant in the thickness. COPYRIGHT: (C)1986,JPO&Japio