Wyniki wyszukiwania - Biblioteka Nauki

1

Diagnostyka magnetyczna zmian własności mechanicznych materiału koła napędnego lokomotywy EU07

100%

Bizoń K.

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2011

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tom T. 11, nr 42

75-82

PL

Autor podjął próbę wykorzystania pomiarów własności magnetycznych (natężenia koercji) ferromagnetyka do wykrywania zmęczeniowej degradacji materiału na przykładzie staliwa LII500. Obiektem badań było koło napędne lokomotywy EU07. Wyniki badań własności magnetycznych odniesiono do badań defektoskopowych prowadzonych metodą wizualną i penetracyjną barwną.

EN

The author has made an attempt to use measurements of magnetic properties (coercivity intensity) of ferromagnetic to detect fatigue material degradation based on the example of LII500 cast steel. Drive wheel of EU07 locomotive was the research object. The results of the research on magnetic properties have been compared with defectoscopic ones carried by means of visual method and dye penetration method.

2

Hindrances associated with examination of two-layer structures with use of the eddy current method

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Dziczkowski L. , Dziczkowska M.

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2009

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tom Vol. 35, nr 1

39-46

EN

Purpose: Determination and description of essential phenomena that occur during examination of two-layer structures with use of the eddy-current method. Development of guidelines to establish procedures that make it possible to find out optimum frequencies of eddy currents, for which measurements of the outer film covering the examined structure exhibit best performance. Estimation of errors that occur when measurements of both geometrical and electrical parameters of the upper film within the two-layer structures are carried out simultaneously. Design/methodology/approach: During the design and scalling of the devices based on phenomenon of eddy currents implying changes of contact coil impedance components, significant influence of the electromagnetic field frequency on measurement results was observed. Additionally, some other phenomena can be observed which causes invalid interpretation of devices indications. Basing on a mathematical model of a contact coil located above a conductive non-ferromagnetic two-layer plate, the sensitivities to the measured parameters are determined. The developed mathematical model serves and the basis to calculate theoretical values of errors when all parameters of the outer film on the examined structure are measured simultaneously. Findings: Depending on specific applications, recommendations enabling proper choice of the electromagnetic field frequency are formulated. Practical implications: Describred phenomena and calculations are useful for the designers of the devices utilising the phenomenon of eddy currents, and also for the users of flaw detectors and conductometers. Remarks included in this paper can be useful for proper interpretation of the observed results and phenomena. Originality/value: Determination of impact coefficients that define how parameters of the two-layer structure are vulnerable to impedance components of the measuring contact coil.

3

Effect of eddy current frequency on measuring properties of devices used in non-destructive measurements of non-ferromagnetic metal plates

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Dziczkowski L.

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2008

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tom Vol. 32, nr 2

77-84

EN

Purpose: To determine optimal frequency of the electromagnetic field that raises eddy currents during the search for surface defects in non-ferromagnetic materials or conductivity measurements by means of eddy currents methods. The frequency choice takes into consideration sensitivity of measuring device, depth of the eddy currents penetration and elimination of undesirable phenomena that affects result of the exploration. Design/methodology/approach: During the design and scalling of the devices based on phenomenon of eddy currents implying changes of contact coil impedance components, significant influence of the electromagnetic field frequency on measurement results was observed. Additionally, some other phenomena can be observed which causes invalid interpretation of devices indications. Basing on a mathematical model of a contact coil located above a conductive non-ferromagnetic plate, the sensitivities to the measured parameters are determined. Furthermore, a novel definition of the eddy currents penetration depth is proposed. Findings: Depending on specific applications, recommendations enabling proper choice of the electromagnetic field frequency are formulated. Practical implications: Describred phenomena and calculations are useful for the designers of the devices utilising the phenomenon of eddy currents, and also for the users of flaw detectors and conductometers. Remarks included in this paper can be useful for proper interpretation of the observed results and phenomena. Originality/value: A modified definition of the actual penetration depth of eddy currents proposed in the paper differs from the classical approach based on the 1/e level. This definition may be especially convenient and useful for operators utilising eddy current devices. Described sensitivity model facilitates setting up the devices for a specific task involved in a different technological process.

4

Selection of the frequency of eddy currents in non-destructive testing of non-ferromagnetic plates

100%

Dziczkowski L.

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2008

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tom Vol. 27, nr 1

43-46

EN

Purpose: To determine the optimal frequency of the electromagnetic field exciting eddy currents during the search for surface defects in non-ferromagnetic materials or at the time of conductivity measurements by means of eddy currents methods. Design/methodology/approach: On the grounds of a mathematical model of a contact coil located above a conductive non-ferromagnetic plate, the sensitivities to the measured parameters were designated. Furthermore, a new definition of eddy currents penetration depth was proposed. Findings: Recommendations facilitating proper selection of the electromagnetic field frequency were formulated, depending on specific applications. Practical implications: The discussed phenomena and calculations are useful not only to constructors of the devices utilising the phenomenon of eddy currents, but also to users of flaw detectors and conductometers. Originality/value: A modified definition of the actual penetration depth of eddy currents is proposed in the paper, which differs from the classical approach based on the 1/e level. The new definition may be very convenient and useful for operators utilising eddy current devices. The described sensitivity model facilitates setting up the devices for a specific task involved in a given process technology.