Wyniki wyszukiwania - BazTech

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Wykrywanie pęknięć hartowniczych w stali łożyskowej 100Cr6 metodą prądów wirowych

Kondej Adam, Jończyk Sylwester, Lasota Piotr

Welding Technology Review

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2023

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R. 95

87--93

PL

W artykule opisano wyniki badań w zakresie identyfikacji i lokalizacji pęknięć hartowniczych w stali łożyskowej 100Cr6 z wykorzystaniem autorskiego urządzenia kontrolno-pomiarowego do badań nieniszczących metodą prądów wirowych Wirotest M2 oraz automatycznego stanowiska AutoWir-S1. Do badań zastosowano głowicę stykową o częstotliwości 861 kHz. System rejestrował zmiany amplitudy napięcia oraz częstotliwości rezonansowej. Wyraźny spadek wartości obydwu parametrów wskazywał na obecność nieciągłości. Efekt krawędziowy powodował wzrost amplitudy napięcia oraz spadek częstotliwości, jednakże zmiany te nie wpłynęły na detekcję pęknięć. Najmniejsze wykryte pęknięcie charakteryzowało się maksymalną szerokością około 20 μm i było niewidoczne okiem nieuzbrojonym. Uzyskane wykresy powierzchniowe jednoznacznie obrazują przebieg oraz lokalizację poszczególnych nieciągłości.

EN

The article describes the results of research on the identification and localization of quenching cracks in 100Cr6 bearing steel using a proprietary non-destructive testing device based on the eddy current method called Wirotest M2 and an automatic stand AutoWir-S1. A surface probe with a frequency of 861 kHz was used for the tests. The system recorded changes in voltage amplitude and resonant frequency. A significant decrease in both parameters indicated the presence of discontinuities. The edge effect caused an increase in voltage amplitude and a decrease in frequency, but these changes did not affect crack detection. The smallest detected crack had a maximum width of about 20 μm and was invisible by the unaided eye. The obtained surface charts clearly illustrate the course and localization of individual discontinuities.

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Coda wave interferometry for monitoring the fracture process of concrete beams under bending test

Knak Magdalena, Wojtczak Erwin, Rucka Magdalena

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 3

art. no. e144118

EN

Early detection of damage is necessary for the safe and reliable use of civil engineering structures made of concrete. Recently, the identification of micro-cracks in concrete has become an area of growing interest, especially when it comes to using wave-based techniques. In this paper, a non-destructive testing approach for the characterization of the fracture process was presented. Experimental tests were performed on concrete beams subjected to mechanical degradation in a 3-point bending test. Ultrasonic waves were registered on a specimen surface by piezoelectric transducers located at several points. Then, the signals were processed taking advantage of wave scattering due to micro-crack disturbances. For early-stage damage detection, coda wave interferometry was used. The novelty of the work concerns the application of the complex decorrelation matrix and the moving reference trace approach for better distinguishment of sensors located in different parts of a crack zone. To enhance coda wave-based damage identification results, optical imaging of crack development was performed by means of digital image correlation measurement. The results obtained showed that the coda wave interferometry technique can be successfully used as a quantitative measure of changes in the structure of concrete. The results also indicated that the course of decorrelation coefficient curves enabled the identification of three stages during degradation, and it depended on the location of acquisition points versus the crack zone.

3

A study on microbial self-healing concrete using expanded perlite

Amjad Usama Bin, Siddique Muhammad Shahid, Shahid Taha, Ahmed Iftikhar, Alogla Saleh M., Ahmad Jawad

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 5

art. no. e146475

EN

The increasing concern for the safety and sustainability of structures is calling for the development of smart self-healing materials and preventive repair methods. This research is carried out to investigate the extent of self-healing in normal-strength concrete by using Sporosarcina aquimarina – NCCP-2716 immobilized in expanded perlite (EP) as the carrier. The efficacy of crack-healing was also tested using two alternative self-healing techniques, i.e. expanded perlite (EP) concrete and direct introduction of bacteria in concrete. A bacterial solution was embedded in EP and calcium lactate pentahydrate was added as the nutrient. Experiments revealed that specimens containing EP-immobilized bacteria had the most effective crack-healing. After 28 days of healing, the values of completely healed crack widths were up to 0.78 mm, which is higher than the 0.5 mm value for specimens with the direct addition of bacteria. The specimen showed a significant self-healing phenomenon caused by substantial calcite precipitation by bacteria. The induced cracks were observed to be repaired autonomously by the calcite produced by the bacteria without any adverse effect on strength. The results of this research could provide a scientific foundation for the use of expanded perlite as a novel microbe carrier and Sporosarcina aquimarina as a potential microbe in bacteria-based self-healing concrete.

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Technologia EMAT w zastosowaniu do diagnostyki gazociągów wysokiego ciśnienia

Witek M., Szałęga M.

Gaz, Woda i Technika Sanitarna

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2015

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Nr 11

387--392

EN

Gas transmission pipelines are commonly inspected by in-line tools equipped with sensors for nondestructive testing. EMAT inspection technology, designed for detection of stress corrosion cracking, is also sensitive to areas of disbanded coating and other crack-like features. An electromagnetic acoustic transducer is used for contactless generating and receiving waves using electromagnetic phenomena. Second part of this publication presents a summary of calculation of the high pressure pipeline with wall defect like longitudinal semi-elliptical crack. The calculations are based on standard BS 7910:2005, which describes the influence of cracks on the pipeline maximum operating pressure.

PL

Gazociągi wysokiego ciśnienie są powszechnie badane przez tłoki do inspekcji wewnętrznej, wyposażone w czujniki służące do diagnostyki stanu ścianki gazociągu. Technologię EMAT zaprojektowano w celu wykrywania skutków korozji naprężeniowej, odspojeń zewnętrznej powłoki izolacyjnej, a także pęknięć materiału stalowego. Elektromagnetyczny przetwornik akustyczny, służy do bezkontaktowego tworzenia i odbioru fal powstałych w skutek zjawisk elektromagnetycznych. W drugiej części publikacji zostały przedstawione obliczenia gazociągu wysokiego ciśnienia z defektem typu pęknięcie wzdłużne półeliptyczne ścianki. Zastosowano algorytm obliczeniowy wg standardu BS 7910:2005 dla oceny istotności przykładowych defektów, pozwalający stwierdzić wpływ pęknięcia na maksymalne ciśnienie robocze gazociągu.

5

Infrared thermography as a new method for quality control of sheet metal parts in the press shop

An Q., Hortig D., Merklein M.

Archives of Civil and Mechanical Engineering

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2012

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Vol. 12, no. 2

148--155

EN

Active dynamic thermography was proved to be a new alternative for crack detection. To achieve zero failure sheet metal production in the press shop, this method was investigated for different steel components, which were directly collected from series production. And the cracks in the presented specimens differ in length and in depth, and a series study on these surface cracks is executed. The crack detection capabilities of active thermography with two different excitation sources were compared: optical and inductive excited thermography. Results of experiments obtained by these two techniques are showed and compared with each other. Opportunities of applying these methods in press shop are discussed.

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Crack detection by the topological gradient method

Amstutz S., Horchani I., Masmoudi M.

Control and Cybernetics

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2005

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Vol. 34, no 1

81-101

EN

The topological sensitivity analysis consists in studying the behavior of a shape functional when modifying the topology of the domain. In general, the perturbation under consideration is the creation of a small hole. In this paper, the topological asymptotic expansion is obtained for the Laplace equation with respect to the insertion of a short crack inside a plane domain. This result is illustrated by some numerical experiments in the context of crack detection.

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Diagnostyka kontrolna węglowego młyna kulowego

Barczewski R., Zielnica M.

Zeszyty Naukowe Politechniki Poznańskiej. Budowa Maszyn i Zarządzanie Produkcją

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2004

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Nr 1

137-146

PL

W artykule przedstawiono zagadnienia diagnostyki kontrolnej węglowego młyna kulowego, a w szczególności stalowych kuł - podstawowych elementów zespołu mielącego. Standardowa procedura kontroli kuł, obejmująca ważenie, pomiar oraz próbę toczenia, nie gwarantuje wykrywania wad strukturalnych i materiałowych (np. pęknięć i porowatości). Zastosowanie innych metod badań nieniszczących, jak radiologia, defektoskopia ultradźwiękowa, metody wizualne do detekcji wad, do obiektu sferycznego nie zawsze jest możliwe i ekonomicznie uzasadnione. Zaproponowano alternatywną metodę badania kuł. Dodatkowa wstępna klasyfikacja została oparta na analizie parametrów drgań swobodnych. Analiza dynamiczna uzyskanego metodą elementów skończonych modelu kuli oraz badania doświadczalne wykazały, że dominujące składowe w widmie drgań swobodnych odpowiadają dziesiątemu i dwunastemu modowi drgań. Zmniejszenie grubości ścianki kuli powoduje wzrost częstotliwości odpowiadającej dziesiątej postaci drgań, która jednak jest mało wrażliwa na występowanie pęknięć. Wykrywanie pęknięć kuli może być oparte na analizie zmian częstotliwości dwunastego modu. W artykule przedstawiono również uproszczony algorytm przetwarzania sygnału drganiowego stosownego w procedurze preselekcji kuł.

EN

The paper presents problems of testing diagnostics of coal ball mill, especially steel balls which are major elements of the milling unit. Standard testing procedure of the balls including: the weighting and measuring as well as rolling test does not guarantee the detection of structural and material failures (i.e. cracks, porosity). Application of other NDT methods, like radiology, ultrasonic testing, visual inspection, to failures detection in spherical object is not always possible and economically justified. Therefore, the alternative test procedure of balls has been proposed. An additional initial classification of balls for the following detailed tests have been based on the analysis of free vibration parameters. The dynamic analysis of the FEM model of the ball and experiments show that frequencies of the dominant components in free vibration spectrum correspond to tenth (f!0) and twelfth (f,2) vibration mode. Decrease of the thickness of the ball wall cause increase of f]0 frequency value which is less sensitive on crack presence.. Detection of ball cracks can be based on the analysis of frequency changes of the twelfth vibration mode. Also the paper presents a simplified algorithm of the vibration signal processing used in the ball preselection procedure.

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Sensitivity analysis of electromagnetic quantities by means of FEM

Gawrylczyk K. M.

Journal of Technical Physics

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2002

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Vol. 43, no 3

323-334

EN

Sensitivity analysis determines the dependence of global or local electromagnetic quantities on geometrical or physical parameters expressed in the form of an objective function. The final aim of the field calculation methods is generally the design of an electromagnetic device. Solution of inverse problem on the basis of the finite elements method (FEM) makes the optimal shape design possible, as well as the identification of material cracks and flaws inside the conducting materials with the help of the eddy-current method. These tasks can be defined similarly for recognition of the spatial distribution of material parameters. The recognition takes place in iterative manner, basing on gradient information derived from the sensitivity analysis. The work deals with sensitivity evaluation in conjunction with finite element algorithms. It will be shown that the sensitivity analysis necessary to solve an inverse problem, requires only a low additional calculation cost.