摘要:

A realistic friction model for simple upsetting is developed. The model combines a rigid-plasticity finite element code with a lubrication analysis. The surface roughness effect on lubricant flow is included by using the average Reynolds equation. The active lubrication regime and appropriate friction factor can then be determined from the current local values of interface variables (mean lubricant film thickness, workpiece roughness and tooling roughness) in addition to the more traditional external variables (interface pressure, sliding speed and strain rate). Numerical results for friction stress and normal pressure under different lubrication conditions are compared with previous numerical and experimental investigations.

ISSN:1040-2004    

DOI:10.1080/10402009708983667

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Testing has been conducted on silicon nitride (Si3N4) in simulated engine exhaust gas environments in four-ball rolling contacts and pin-on-disk sliding contacts to 590°C. Utilizing a steel race, the depth of the. wear track formed at the Si3N4/Si3N4rolling contact in the presence of exhaust gas was roughly one-half that formed in the presence of N2alone. Deposition of lubricous microcrystalline graphite carbon from CO within the exhaust was confirmed by Raman spectroscopy. Removal of H2O from the exhaust gas further reduced rolling wear. Exhaust gas alone provided no benefit to Si3N4/Si3N4sliding contacts, where the rate of wear greatly exceeds the rate at which lubricous carbon may deposit from the exhaust environment. As compared to that measured in the presence of N2alone, the directed admixture of hydrocarbon (C2H2) to the exhaust gas enhanced the lubrication of Si3N4with reductions of up to 25-fold in rolling wear, 650-fold in steady-stale sliding wear rate and 20-fold in sliding friction.Presented at the 51st Annual Meeting in Cincinnati, Ohio May 19–23, 1996

ISSN:1040-2004    

DOI:10.1080/10402009708983668

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Wear measurements are notoriously variable. Even the experiments with the same type of material and test machine can give significantly different results. Such discrepancies are mostly due to a lack of adequate control of test conditions and unreliable measurement techniques. Specification and control of certain tribological quantities are a necessary prerequisite for obtaining reproducible and comparable results. To proceed forward in this direction, it is essential to review and analyze the existing test procedures and measuring techniques. In this study, the authors investigated the reliability of the most common wear volume measurement approaches and explored the influence of surface finish on the friction and wear performance of Al2O3ceramics. The wear tests were performed with a pin-on-disc machine on polished and ground surfaces of Al2O3disks. The wear volume was measured from height displacement, weight loss, and from worn surface profilometry. The results indicated that the wear volume measurements by surface profilometry and height displacement (by transducer) were highly reliable. The wear rates of ground and polished alumina were in the order of 10−7mm3/m·N. Finally, for the specific surface roughness range (Ra = 0.03 to 0.4 μm) explored in this study, the surface finish was only important during the initial run-in period.

ISSN:1040-2004    

DOI:10.1080/10402009708983669

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Stress concentration at the interface between the matrix of metal and hard inclusions is simulated photoelastically, using a two-dimensional polymer model with polymer inclusions of higher elastic modulus. The effect of inclusion shape, size, location, orientation, elastic modulus, of the strength of bonding between inclusions and matrix, and of the presence of an elastic transition zone is evaluated. Results have served as a guide in selecting more favorable inclusion configurations in the rational design of a wear-resistant steel alloy.

ISSN:1040-2004    

DOI:10.1080/10402009708983670

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:1040-2004    

DOI:10.1080/10402009708983671

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:1040-2004    

DOI:10.1080/10402009708983672

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor