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Article

Mustafa Kadıoğlu and Ertuğrul Durak

The purpose of this study was to examine the effect of the magnetic field to the friction coefficient in the rolling element bearings which exists in electric motors.

Abstract

Purpose

The purpose of this study was to examine the effect of the magnetic field to the friction coefficient in the rolling element bearings which exists in electric motors.

Design/methodology/approach

To achieve this, the test rig was modified to adjust the density of the magnetic flux applied to the rolling ball element bearing. Experiments were carried out in the magnetic field from 0 to 7.5 mTesla at magnetic flux density range from 15, 40 and 65 N constant loads. Also, its rotary speed selected as 100, 200, 400, 800 to 1200 rpm, respectively.

Findings

In the majority of the experiments, it was observed that the magnetic field affected the friction coefficient. This influence reduced the friction coefficient in some experimental conditions and increased in some of them.

Originality/value

In the literature, there are very few studies on the effect of magnetic flux density to the friction coefficient in these rolling element bearings. It has become clear that more studies have been conducted on the effects of the magnetic field and/or electrical current on bearing damages and failures. This aspect is a study with specificity.

Details

Industrial Lubrication and Tribology, vol. 71 no. 10
Type: Research Article
ISSN: 0036-8792

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Article

Michal Styp-Rekowski, Eugeniusz Manka, Maciej Matuszewski, Monika Madej and Dariusz Ozimina

The purpose of this paper was to create conditions for the correct decision concerning an exchange of the used rope for a new one. A cognitive goal was to indicate the…

Abstract

Purpose

The purpose of this paper was to create conditions for the correct decision concerning an exchange of the used rope for a new one. A cognitive goal was to indicate the causes of its wear and determining its mechanism reliability and durability.

Design/methodology/approach

The magnetic, organoleptic and strength standard tests of lifting triangle-strand ropes of a mining hoist were carried out. This way the current state of the tested rope was defined.

Findings

On the basis of an analysis of the results of the performed tests: magnetic, organoleptic and fatigue tests, it can be said that the magnetic one is accurate enough only to indicate the place of the rope’s biggest weakening, though the degree of weakening is not defined precisely – with significant excess. The accurate rope’s destruction degree is indicated by the strength tests.

Practical implications

The results of described investigations can improve safety of the mining rope mechanisms operation, even for an increased resource.

Originality/value

The elementary wear processes, which are the basic reason for the destruction of the rope, are indicated. Rope destruction is caused mainly by tribological factors: abrasion, corrosion and fatigue wear. Magnetic tests are accurate enough only to indicate the place of the rope’s biggest weakening (qualitative index). Most precisely, the rope’s destruction degree (quantitative index) can be found by the strength tests.

Details

Industrial Lubrication and Tribology, vol. 67 no. 1
Type: Research Article
ISSN: 0036-8792

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Article

Xiaoyang Wang, Jiusheng Bao, Jinge Liu, Yan Yin, Tonggang Liu and Shaodi Zhao

This paper aims to develop of magnetic field controlled friction braking technology, a novel brake friction material with magnetic was designed and prepared in this paper.

Abstract

Purpose

This paper aims to develop of magnetic field controlled friction braking technology, a novel brake friction material with magnetic was designed and prepared in this paper.

Design/methodology/approach

The permalloy, a soft magnetic material, was selected as an additive to design and prepare the magnetic brake material. The friction, wear performance and permeability of each brake pads were investigated by experiments. By choosing the performance of friction coefficient fluctuation, friction coefficient deviation and mean wear rate as optimization parameters, the formulation of the magnetic friction material was optimized based on Fuzzy theory by using analytic hierarchy process methods and SPSS software.

Findings

The results showed that the developed soft magnetic friction material has not only superior friction coefficient, permeability and inferior wear rate but also good physical and mechanical properties.

Originality/value

Permalloy powder was added to the formulation of friction material to achieve a new functional friction material with high magnetic permeability. It is believed that this research will be of great theoretical and practical significance to develop both new brake materials and active control technology of the braking process in the future.

Details

Industrial Lubrication and Tribology, vol. 73 no. 2
Type: Research Article
ISSN: 0036-8792

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Article

Deboshree Roy, Balbhadra Kumar Kaushik and Rakesh Chakraborty

Eddy current testing (ECT) is widely used in the non-destructive evaluation of materials in different industries. In this paper, ECT has been used to detect the presence…

Abstract

Purpose

Eddy current testing (ECT) is widely used in the non-destructive evaluation of materials in different industries. In this paper, ECT has been used to detect the presence of cracks in boiler tubes. The most important feature in ECT is the way in which the eddy currents are induced and detected in the sample. The authors have tried to design a new sensor that is effective in detecting cracks in boiler tubes. The purpose of this paper is to study the response of this sensor to cracks of different depths and dimensions.

Design/methodology/approach

The designed eddy current sensor is equipped with an exciting and a sensing coil. An alternating current is passed through the exciting coil thus producing eddy currents. The sensing coil scans the outer surface of the boiler tube and looks for abrupt changes in output signals resulting from sharp discontinuities in structure.

Findings

The sensor designed can detect the position of the crack. The presence of crack is indicated by a reduction in the induced voltage in the sensing coil. The sensor is also used for characterisation of the cracks, and can distinguish between cracks of varying shape, size and depth. The sensitivity of the sensing coil to cracks is dependent on operating conditions, such as frequency and voltage of the excitation signal.

Practical implications

The new sensor designed is used to detect defects in boiler tubes in power plants. However, the operating conditions, such as excitation frequency and amplitude will vary with composition of the boiler tubes.

Originality/value

The new eddy current sensor designed for crack detection is an E-shaped core coil. The shape of the coil provides a high permeability path to the magnetic field lines, thus reducing the loss of the field produced. This helps in improving the sensitivity of the coil, and makes the detection system effective in detecting hairline cracks.

Details

Sensor Review, vol. 33 no. 4
Type: Research Article
ISSN: 0260-2288

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Article

Jin Jin, Hexi Baoyin and Junfeng Li

The purpose of this paper is to propose an attitude determination and control scheme for a low‐cost Micro‐satellite with defective inertia. Restricted by the payload…

Abstract

Purpose

The purpose of this paper is to propose an attitude determination and control scheme for a low‐cost Micro‐satellite with defective inertia. Restricted by the payload design, the z‐axis inertia of this satellite is larger than the x and y axes, which is unstable for natural attitude dynamics.

Design/methodology/approach

An original operation mode is designed to avoid z axis from long‐time pointing to the sun during damping, which avoids some unexpected damage. In attitude determination design, EKF and UKF algorithms are compared on estimation accuracy, convergence time and computation complexity in attitude estimation design, which is referred to determine the final estimation scheme. A DSP‐based hardware solution is achieved and a semi‐physical testing and simulation system is built.

Findings

Simulation results show the 3‐axis stable mode can be built with the proposed scheme, and the unprotected facet of the satellite can be kept away from long‐time pointing to the sun.

Originality/value

The proposed ADCS scheme can be a reference for the future Micro‐satellite programs which share the similar configuration.

Details

Aircraft Engineering and Aerospace Technology, vol. 85 no. 5
Type: Research Article
ISSN: 0002-2667

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Article

G. Clifton

Non‐destructive testing (NDT) makes use of the controlled application of physical phenomena to materials so that interpretation of signals derived from the materials…

Abstract

Non‐destructive testing (NDT) makes use of the controlled application of physical phenomena to materials so that interpretation of signals derived from the materials indicates their fitness, or otherwise, to perform a design function. The purpose of NDT is to ensure that mainly load carrying components and structures are free from defects. Established non‐destructive testing has become of primary importance in aircraft maintenance and manufacture both as a positive indication for safety and as a method of saving costs. This article written for aircraft engineers is a broad review of the development of NDT in their industry and a brief indication of the status of its various components today.

Details

Aircraft Engineering and Aerospace Technology, vol. 47 no. 6
Type: Research Article
ISSN: 0002-2667

Abstract

Details

Anti-Corrosion Methods and Materials, vol. 50 no. 4
Type: Research Article
ISSN: 0003-5599

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Article

Kurt P. Rohrbach

Guidelines for making a wise choice when selecting high temperature alloys are provided. Four groups of alloys are discussed, along with helpful selection criteria…

Abstract

Guidelines for making a wise choice when selecting high temperature alloys are provided. Four groups of alloys are discussed, along with helpful selection criteria. Substantial benefits accrue from contemporary alloy manufacturing techniques. Process databases and state‐of‐the‐art forging equipment significantly impact product quality, consistency and cost effectiveness. Finally, the author suggests that the elimination of unnecessary test requirements offers potential for savings in time and money. He feels that alloy integrity can be assured by any producer who can demonstrate narrow limits of compositional control, as well as melting, remelting and hot working controls.

Details

Aircraft Engineering and Aerospace Technology, vol. 70 no. 3
Type: Research Article
ISSN: 0002-2667

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Article

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United…

Abstract

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United States National Advisory Committee for Aeronautics and publications of other similar Research Bodies as issued.

Details

Aircraft Engineering and Aerospace Technology, vol. 27 no. 5
Type: Research Article
ISSN: 0002-2667

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Article

Mohammad I. Albakri, Logan D. Sturm, Christopher B. Williams and Pablo A. Tarazaga

This work proposes the utilization of electromechanical impedance measurements as a means of non-destructive evaluation (NDE) for additive manufacturing (AM). The…

Abstract

Purpose

This work proposes the utilization of electromechanical impedance measurements as a means of non-destructive evaluation (NDE) for additive manufacturing (AM). The effectiveness and sensitivity of the technique for a variety of defect types commonly encountered in AM are investigated.

Design/methodology/approach

To evaluate the feasibility of impedance-based NDE for AM, the authors first designed and fabricated a suite of test specimens with build errors typical of AM processes, including dimensional inaccuracies, positional inaccuracies and internal porosity. Two polymer AM processes were investigated in this work: material jetting and extrusion. An impedance-based analysis was then conducted on all parts and utilized, in a supervised learning context, for identifying defective parts.

Findings

The newly proposed impedance-based NDE technique has been proven to be an effective solution for detecting several types of print defects. Specifically, it was shown that the technique is capable of detecting print defects resulting in mass change (as small as 1 per cent) and in feature displacement (as small as 1 mm) in both extruded nylon parts and jetted VeroWhitePlus parts. Internal porosity defects were also found to be detectable; however, the impact of this defect type on the measured impedance was not as profound as that of dimensional and positional inaccuracies.

Originality/value

Compared to currently available NDE techniques, the newly proposed impedance-based NDE is a functional-based technique with the advantages of being cost-effective, sensitive and suitable for inspecting AM parts of complex geometry and deeply embedded flaws. This technique has the potential to bridge the existing gaps in current NDE practices, hence paving the road for a wider adoption of AM to produce mission-critical parts.

Details

Rapid Prototyping Journal, vol. 23 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

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