摘要:

AbstractCouple stresses affect lubrication when additives are used or the lubricant contains long‐chain molecules. Such couple stresses may have a considerable effect on the behaviour of bearings in practice. The influence of couple stresses and lubricant inertia on the mechanical parameters of a curvilinear thrust bearing with a squeeze film is considered in this paper. Simulation of the squeeze‐film behaviour of a human joint modelled as a spherical bearing is discussed as an exam

ISSN:1354-4063    

DOI:10.1002/tt.3020080302

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

摘要:

AbstractThis paper presents a dynamic analysis of a contact system subjected to an applied normal vibration. The tangential motion of the system is found to exhibit stick‐slip behaviour dependent on the applied vibration, even in the absence of a difference in static and kinetic friction or a negative gradient in the friction‐velocity relation. The analysis leads to the development of a criterion for stick‐slip in the form of an equation defined in terms of the system and input parameters. This criterion is also presented graphically and is assessed through a series of experiments. The analysis and measurements show that stick‐slip occurs for a significantly wider drive velocity range when the normal vibration applied is near the natural frequency of the drive system. In addition, when stick‐slip occurs in the presence of a normal vibration, the frequency of stick‐slip is found to lock in to the frequency of the applie

ISSN:1354-4063    

DOI:10.1002/tt.3020080303

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

摘要:

AbstractViscoelastic‐viscoplastic behaviour is usually not taken into account in models describing the scratch properties of polymeric surfaces. In the case of a standard indentation test with stationary tip, the elastic‐plastic boundary and the boundary of the region being subjected to hydrostatic pressure beneath the tip are understood. Such well‐known models have been used in this study to understand the geometry of the groove left on the surface of a viscoelastic‐viscoplastic body by a moving diamond tip. A new apparatus was built that can control the velocity of the tip over the range 1 μm/s to 15 mm/s, at several different temperatures from −10 to +100°C. The material used was a commercial grade of cast poly(methyl methacrylate) (PMMA). The normal and tangential loads and groove size were used to evaluate the dynamic hardness, which behaved like a stress‐ and temperature‐activated process. The values for the activation energy and volumes of the dynamic hardness and of the interfacial shear stress were in good agreement with the mechanical properties usually att

ISSN:1354-4063    

DOI:10.1002/tt.3020080304

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

摘要:

AbstractWear experiments on ZnAl12Pb alloy and Pb‐based Babbitt alloy (Zch PB16‐16‐2) have been carried out under identical conditions. The wear behaviour of the alloys has been investigated using scanning electron microscopy and surface profile analysis. The results show that ZnAl12Pb alloy is a good material for bushing or bearing applications, and the wear resistance of ZnAl12Pb alloy is better than that of Pb‐based Babbit

ISSN:1354-4063    

DOI:10.1002/tt.3020080305

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

摘要:

AbstractIn the chocolate production process, the moisture content of ground cocoa is removed in a spray‐drying unit, in which wet cocoa is pumped through a high‐pressure pump. Wear occurs in this high‐pressure pump, which can cause problems in the system. Originally, valves and beds were made of AISI 316 Ti austenitic stainless steel, and their average wear life was less than 280 h, obviously too short for use in industrial production. The aim of the research reported in this paper was to investigate ways to increase the wear life of these parts. In this respect six different materials were tested. Valves and beds were produced from four different steels and two powder metals. The steel parts were hardened by heat treatment. All the parts were electroplated with CrN or TiN. Wear life tests were carried out, and it was shown that AISI M2 high‐speed steel valves and beds gave the longest wea

ISSN:1354-4063    

DOI:10.1002/tt.3020080306

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020080307

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020080308

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY

ISSN:1354-4063    

DOI:10.1002/tt.3020080301

出版商:John Wiley&Sons, Ltd    

年代:2002

数据来源: WILEY