Effects of shaft shape errors are studied on dynamic characteristics of a rotor-bearing system. Stability characteristics of the cylindrical journal bearing are studied. It is shown that the rotating speed at which the oil whip occurs increases when the shape errors exit. And, there is a threshold speed of the bearing with shaft shape errors; …
Three types of surfaces in the Schroeder–Webster (SW) theory, i.e., sliding, mixed, and sticking surfaces, have been verified via finite element analysis of an axisymmetric compression test for a metallic specimen. Judging from (i) the radial profile of the pressure at the top elements and (ii) the radial displacement at the top nodes, the three …
Hydrophobic and self-cleaning photocatalytic ceramics and concrete with potential for the superhydrophobicity are promising novel materials for civil engineering applications including buildings, bridges, road pavements, and airport runways. Due to embedded liquid-repellent properties, such materials have low water and salt absorption and, therefore, enhanced durability. However, in applications requiring high traction (e.g., tire and pavement), …
Element 45 in our International Year of the Periodic Table series is rhodium. This rare, unreactive element finds uses in the catalytic converters in our cars and in electroplated white gold jewellery. Rhodium is one of a number of transition metals used in the catalytic converters found in diesel and petrol cars. These converters help …
A nonlinear dynamic model is proposed to investigate the dynamic interactions between the rolling element and cage under rotational speed fluctuation conditions. Discontinuous Hertz contact between the rolling element and the cage and lubrication and interactions between rolling elements and raceways are considered. The dynamic model is verified by comparing simulation result with the published …
In this study, tribological characteristics of diethylene glycol dimethyl ether (DGM)/diethylene glycol dimethyl ether–diesel blend A (10 vol% DGM + 90 vol% diesel)/diesel were compared after being subjected to quill roller-ball friction and four-ball friction tests. The lubricity and antiwear property of blend A were worse than those of diesel, albeit considerably better than those …
Element 44 in our International Year of the Periodic Table series is ruthenium. This element finds uses in electronics, fountain pens, and in some fingerprinting techniques. Ruthenium is added to alloys of platinum and palladium used in electrical contacts. These are used as switches in a wide array of electronic devices. ‘Iridium’ fountain pen nibs …
Element 43 in our International Year of the Periodic Table series is technetium. The periodic table’s first artificially created element, its radioactivity allows it to be used in medical imaging. The artificial creation of element 43 was originally claimed by a group of German chemists in 1925. They named their newly discovered element masurium. However, …
Element 42 in our International Year of the Periodic Table series is molybdenum. Found in steel and used in lubricants in some engines, it’s also found in enzymes in our bodies that help us process sulfites in various foods. Molybdenum is added to steel, widely used as a building material, to make it corrosion resistant. …
Element 41 in our International Year of the Periodic Table series is niobium. A hypoallergenic metals, it’s found in superconducting magnets in particle accelerators, as well as in the glasses many of us wear to correct our vision. Some metals, such as nickel, can cause allergic reactions in some people when in contact with the …
