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Article

Walter Holweger, Frank Walther, Jörg Loos, Marcus Wolf, Jürgen Schreiber, Werner Dreher, Norbert Kern and Steffen Lutz

Bearings in field applications with high dynamic loading, e.g. wind energy plants, suffer from sudden failure initiated by subsurface material transformation, known as…

Abstract

Purpose

Bearings in field applications with high dynamic loading, e.g. wind energy plants, suffer from sudden failure initiated by subsurface material transformation, known as white etching cracks in a typical scale of μm, preferably around the maximum Hertzian stress zone. Despite many investigations in this field no precise knowledge about the root cause of those failures is available, due to the fact that failure under real service conditions of wind energy plants differs from what is known from test rig results in terms of contact loading, lubrication or dynamics. The purpose of this paper is to apply Barkhausen noise measurement to a full bearing test ring running under conditions of elastohydrodynamic lubrication (EHL) with high radial preload.

Design/methodology/approach

Full bearing tests are carried out by use of DGBB (Deep Grove Ball Bearings) with 6206 specification, material set constant as 100Cr6, martensitic hardening, 10‐12 percent maximum retained austenite and radial preload of 3500 MPa. Speed is set 9000 rpm, temperature is self setting at 80°C by test conditions. For tests, synthetic hydrocarbon base oil (Poly‐α‐Olefine) with a 1 percent amount of molydenum‐dithiophosphate (organic chain given as 2‐ethylhexyl) was used.

Findings

Non‐destructive fractal dimension analyses by use of Barkhausen noise measurements is of versatile value in terms of recording bearing manufacturing processes, but can also be part of non‐destructive condition monitoring of bearings in field applications, where predictive reactive maintenance is crucial for availability of the plant.

Research limitations/implications

Barkhausen noise signal recording may also be valuable for case studies related to microstructure changes of steel under operation conditions. Bearings are exposed in plenty of conditions to phenomena such as straying currents, subsequently straying magnetic fields. Hardly anything is known about how microstructure of bearing steel is susceptible to such conditions. This will be part of further studies.

Originality/value

Results given in the paper show that sudden bearing failure, according to formation of subsurface material property changes might be driven by activities of dislocations. Since those activities start with sequences of stress field‐induced formation of domains, later by formation of low‐angle subgrains, and at least phase transformation, recording of the Barkhausen signal would lead to real predictive condition monitoring in applications where a highly dynamic loading of the contact, even with low nominal contact pressure leads to sudden failure induced by white etching.

Details

Industrial Lubrication and Tribology, vol. 64 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

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Article

Walter Holweger, Marcus Wolf, Frank Walther, Werner Trojahn, Annette Mütze, Jan Kunzmann, Jürgen Schreiber, Joachim Mayer and Manuela Reichelt

The purpose of this paper is to show how controlled exposure of electromagnetic fields toward bearing steel vulnerates the microstructure. The ability of Barkhausen Noise

Abstract

Purpose

The purpose of this paper is to show how controlled exposure of electromagnetic fields toward bearing steel vulnerates the microstructure. The ability of Barkhausen Noise signal processing is used for detecting phenomena such as dislocation and subgrain formation processes as the beginning of later failures.

Design/methodology/approach

A Barkhausen noise signal measurement equipment is used for detecting subsurface distress of 100Cr6 as a function of the applied electromagnetic and mechanical stress. Barkhausen noise signal is mathematically processed by use of fractal dimension analysis.

Findings

The paper cleary reveals significant impact of electromagnetic field in junction with mechanical loading. Electromagnetic impact depends on the magnitude of the field.

Research limitations/implications

Research limitations are given by the fact that in real field applications, e.g. wind power plants, bearings are exposed by multiple influences and the methodology is not applicable to those conditions.

Practical implications

The methodology can be applied to real field applications in condition monitoring systems. Up to now, no reasonable on‐line measurement is in use determining sub surface fatigue phenomena. The paper hence, reveals the possibility to raise condition monitoring into a new perspective.

Originality/value

The use of Barkhausen noise signal processing, as presented here, is original with respect to real field applications, such as wind power plants with a high demand in condition monitoring, especially off‐shore plants.

Abstract

Details

Industrial Lubrication and Tribology, vol. 54 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

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Article

Adam Ruszczyk and Krzysztof Sokalski

The purpose of this paper is to present modelling of power losses dependences on temperature in soft magnetic materials exposed to non-sinusoidal flux waveforms and DC…

Abstract

Purpose

The purpose of this paper is to present modelling of power losses dependences on temperature in soft magnetic materials exposed to non-sinusoidal flux waveforms and DC bias condition.

Design/methodology/approach

Scaling theory allows the power loss density to be derived in the form of a general homogeneous function, which depends on the peak-to-peak of the magnetic inductance ΔB, frequency f, DC bias HDC and temperature T. The form of this function has been generated through the Maclaurin expansion with respect to scaled frequency, which suit very much for the Bertotti decomposition. The parameters of the model consist of expansion coefficients, scaling exponents, parameters of DC bias mapping, parameters of temperature factor and tuning exponents. Values of these model parameters were estimated on the basis of measured data of total power density losses.

Findings

The main finding of the paper is a unified methodology for the derivation of a mathematical model which satisfactorily describes the total power density losses versus ΔB, f, HDC, and T in soft magnetic devices.

Research limitations/implications

Still the derived method does not describe dependences of the power density loss on shape and size of considered sample.

Practical implications

The most important achievement is of the practical use. The paper is useful for device designers.

Originality/value

This paper presents the algorithm which enables us to calculate core losses while the temperature is changing. Moreover, this method is effective regardless of soft magnetic material type and the flux waveforms as well as the DC bias condition. The application of scaling theory in the description of energy losses in soft magnetic materials justifies that soft magnetic materials are scaling invariant systems.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 34 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Abstract

Details

Industrial Lubrication and Tribology, vol. 53 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

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Article

Qiquan Chen, Ji Weng, Stephen Corcoran and Chenhao Fan

The performance of the building envelope of a large-scale public building significantly influences the energy consumption of such a building. This study aims to determine…

Abstract

The performance of the building envelope of a large-scale public building significantly influences the energy consumption of such a building. This study aims to determine the best strategy for the envelope by examining the engineering design of the building in Nanchang University. The building shape coefficient, sun-shading strategies, window–wall ratio, roof, and walls were studied through a method involving multilayer feed-forward neural network model simulations. Results show that the optimum shape coefficient value is 0.32. The combination of interior and exterior blinds and electrochromic glass is the ideal option to reduce the increase in the energy consumption of the architecture caused by solar radiation. Maintaining the window–wall ratio at 0.4 is ideal. A green roof exerts a minimal effect on building energy consumption decrease (only 0.4%). Applying the strategy of vertical greening to the external wall can reduce cooling energy consumption by as much as 5.4%. Adopting the best envelope strategy combination can further decrease energy consumption by 20.8%. This strategy is also applicable to the middle and lower reaches of Yangtze River in China, which flow through Nanchang and have a climate similar to that of the said area. Future research should be directed toward applying artificial neural networks to quantitatively evaluate the effects of a design strategy and produce the best design strategy combination.

Details

Open House International, vol. 41 no. 3
Type: Research Article
ISSN: 0168-2601

Keywords

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Article

Kin Ho Lo, Chi Tat Kwok, Hong Cheng Kuan, Weng Kin Chan and Wenji Ai

The purpose of this paper is to characterize the pitting behaviour of sigma-phase-containing duplex stainless steel and investigate the correlation between magnetic…

Abstract

Purpose

The purpose of this paper is to characterize the pitting behaviour of sigma-phase-containing duplex stainless steel and investigate the correlation between magnetic susceptibility and pitting potentials.

Design/methodology/approach

Use an alternating current (AC) magnetic susceptometer to trace the change in magnetic susceptibility associated with sigma phase formation and systematic study of the effects of sigma precipitation on pitting parameters as obtained using the anodic potentiodynamic polarization test.

Findings

The precipitation of sigma phase impairs the general and pitting corrosion resistance of duplex stainless steel. The pitting potential, the corrosion potential and the AC magnetic susceptibility have good correlations. Unlike the pitting potential and the corrosion potential, the passive current and the corrosion current do not seem to possess any trend with annealing time.

Originality/value

The correlation between AC magnetic susceptibility and pitting parameters has not been reported in the literature before.

Details

Anti-Corrosion Methods and Materials, vol. 62 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

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Article

Ruben B.O. Acevedo, Klaudia Kantarowska, Edson Costa Santos and Marcio C. Fredel

This paper aims to generate a review of available techniques to measure Residual Stress (RS) in Ti6Al4V components made by Ti6Al4V.

Abstract

Purpose

This paper aims to generate a review of available techniques to measure Residual Stress (RS) in Ti6Al4V components made by Ti6Al4V.

Design/methodology/approach

State of the art; literature review in the field of Residual Stress measurement of Ti6Al4V parts made by selective laser melting (SLM).

Findings

Different Residual Stress measurement techniques were detailed, regarding its concept, advantages and limitations. Regarding all researched references, hole drilling (semi destructive) and X-ray diffraction (nondestructive) were the most cited techniques for Residual Stress measurement of Ti6Al4V parts made by SLM.

Originality/value

An extensive analysis of RS measurement techniques for Ti6Al4V parts made by SLM.

Details

Rapid Prototyping Journal, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1355-2546

Keywords

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Article

A.W. Morley

AIRSCREW noise, engine noise and aerodynamic noise combine to produce the high noise level of an aeroplane. Much information has been obtained experimentally concerning…

Abstract

AIRSCREW noise, engine noise and aerodynamic noise combine to produce the high noise level of an aeroplane. Much information has been obtained experimentally concerning these noises and the loudness level they produce when occurring together. The possibility of applying this information, to predict the noise level of projected aircraft, recently promoted a further review of the data, and some new expressions were framed, which, together with other older and well‐tried formulæ, linked together tolerably well the results of the several experiments. These empirical laws, which have proved of considerable value in several problems relating to the improvement of aeroplane noise, are now put forward. At the same time the basic experiments are outlined so that those who may use the expressions will be aware of possible limitations.

Details

Aircraft Engineering and Aerospace Technology, vol. 11 no. 5
Type: Research Article
ISSN: 0002-2667

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Article

H.E. Wimperis

THE achievement of a reasonable degree of silence in aircraft cabins is chiefly difficult because of the amazing intensity of the noise made by the airscrew and engine…

Abstract

THE achievement of a reasonable degree of silence in aircraft cabins is chiefly difficult because of the amazing intensity of the noise made by the airscrew and engine. There is, in addition, the difficulty of excluding this noise from the cabin without unduly adding to the weight of the structure.

Details

Aircraft Engineering and Aerospace Technology, vol. 2 no. 4
Type: Research Article
ISSN: 0002-2667

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