摘要:

AbstractElectrorheological (ER) fluids are fluids that undergo changes in their rheological properties in the presence of an applied electrical field. The change in the flow properties with an applied electrical field has led to their being investigated for use as ‘smart’ lubricants. The Bingham model is currently used to describe the behaviour of these fluids. In this work, the Bingham model parameters of a commercially available ER fluid are obtained using an axial flow concentric‐cylinder rheometer. Two methods are used to determine these parameters. One is the Weissenberg (—Rabinowitsch) method applied to thin annular slits, to obtain corrected stress—strain rate information. The other method involves directly fitting the velocity—pressure curve data to the axial flow rate equation of a Bingham fluid through concentric cylinders. The results obtained by these two methods differ by as much as 49.4 and 63.5% for the yield stress and viscosity, respectively.It is observed for this ER fluid that the yield stress increases according to a power law relationship with the applied electrical field. The viscosity appears to decrease linearly with an increase in the applied elect

ISSN:1354-4063    

DOI:10.1002/tt.3020050302

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractThis paper deals with prediction of wear in spur gears, which has been calculated using an approach in which the wear depth on a tooth surface is integrated over time using the Euler integration method. Variations in pressure distribution over the surface have been considered, as well as changes in curvature and surface profile of the teeth as they wear. The paper focuses on the use of an appropriate wear model for simulating wear using calculated conditions between high‐performance slow‐running lubricated spur gears. A numerical model for prediction of surface interaction of spur gears developed earlier by the authors has been applied as the basis for the simulation of wear using different wear models. Owing to the nature of the wear models, methods of calculating the contact temperature have been investigated for the specific case of interacting gear teeth. It was found that a linear wear model, when compared with a more complex oxidation model and with a model based on adsorption of lubricant molecules, satisfactorily predicts wear. It was also found that it is the geometry of the gears that causes sliding velocity to be the dominant wear‐inducing factor, and so determines the general nature of the wear beha

ISSN:1354-4063    

DOI:10.1002/tt.3020050303

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractThe crater grinding test was originally developed for micro‐abrasion evaluation of thin hard coatings. It is capable of determining the wear constants of the coating and substrate individually, even for very thin coatings. Crater grinding micro‐abrasion tests also make very small wear scars and are thus virtually non‐destructive.This paper evaluates modifications of the crater grinding test configuration in order to increase its accuracy and repeatability. In particular, new geometries of the wearing wheel have been tested on bulk samples of cemented carbides and alumina, and the effects of misalignments in the test equipment are also investigated. The proposed improvements to the test are shown to generate results with better accuracy and repeatab

ISSN:1354-4063    

DOI:10.1002/tt.3020050304

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractA software‐based measurement system using both analogue data acquisition and digital communication via a general‐purpose interface bus (GPIB) board has been developed for analysis and evaluation of disc brake squeal. The system is built around a computer and based on commercial software. Brake pressure and torque, rotational speed, five different temperatures, and sound emission are logged once a second. If the sound is characterised as a squeal it is saved to file together with the other parameters.The measurement system is very flexible, allowing for different types of instruments and sensors to be used by adapting the software. Furthermore, the same software is used for evaluation of the collected data.Mechanically, the equipment consists of a complete front wheel suspension where the original brake disc and caliper are mounted in a steel tube chassis. The brake disc is driven by a DC electric motor, while a hydraulic system provides the brake pressure. Brake pressure and rotational speed can be controlled independen

ISSN:1354-4063    

DOI:10.1002/tt.3020050305

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractThis paper looks at the performance of plain, longitudinally and transversely grooved journal bearings. An experimental apparatus was created to test the performance, in terms of frictional torque under static and dynamic loading, of each of the three bearing types, to try and understand whether grooving created a different film thickness. The tests were carried out for various combinations of load and speed. The results showed an agreement between theoretical and experimental values that gave some confidence in the experimental methods, and showed the frictional torques between the plain and longitudinally grooved bearings to be similar at all loads, and at lower rather than higher speeds, while those of the transversely grooved bearing differed from the others.

ISSN:1354-4063    

DOI:10.1002/tt.3020050306

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractOil filters contain useful information on wear that has occurred in the oil‐wetted mechanical system. However, filter analysis for wear detection is seldom performed, because the method is fairly cumbersome. On the other hand spectral oil‐analysis can be economically done in highly automated laboratories and is therefore widely accepted.This paper describes the case involving a small passenger car diesel engine, where the results of the filter analysis were compared with the results of simultaneously performed oil analysis using X‐ray fluorescence. Oil and filter samples were analysed after each 10,000 km, when oil and filter changes took place, over the life of the engine to 165,000 km.The results, as derived from the filter samples, showed a roughly shaped bath‐tub curve development of the wear rate before the final stage of serious deterioration. However, the oil analysis did not confirm this trend. It is believed that the different in characteristics between a filter sample and an oil sample, and the effects of particle size and of oil filtration on the oil sample, may cause this discrepancy. If the latter is the case, care has to be taken in oil sampling for wear analysis, particularly in systems with fine full‐flow filtration.Suggestions are made at the end of the paper for the design of dedicated diagnostic filters for wear debris

ISSN:1354-4063    

DOI:10.1002/tt.3020050307

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractBicycles are an important means of transport — over 20 million are manufactured worldwide each year, and, because their source of motive energy is human, their energy conversion, as measured by their resistance to motion, is critical. The bearings used in bicycles are rolling bearings, but are normally of different materials and construction quality to the roller bearings used in other applications.The present paper is intended to provide an indication of the phenomena influencing the resistance to motion and loss of energy of these bearings, and is based on a rolling bearing test stand designed by the author. A mathematical model derived from experimental observation is presented, and the theoretical results compared with experimental result

ISSN:1354-4063    

DOI:10.1002/tt.3020050308

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

摘要:

AbstractThe effect of the composition of a base oil matrix on additive response is an indication of its behaviour in a dynamic system. In this paper, a novel method involving quantitative1H and13C NMR to explain the molecular chemistry of base oil is used. Oxidative degradation of base oils (pure as well as additivated) has been studied using DSC. The results are explained in terms of molecular composition of the different base stocks to get a clear understanding of additive response in a matrix of different hydrocarbon oils.

ISSN:1354-4063    

DOI:10.1002/tt.3020050309

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020050310

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020050311

出版商:John Wiley&Sons, Ltd    

年代:1999

数据来源: WILEY