Tribological Characteristics of Natural Fiber Reinforced Polyester Hybrid Composites

In order to investigate the wear behavior and tooth damage of Madar and Bauhinia Racemosa fibers reinforced polyester, the composite gears were fabricated with varying the fiber weight percentages of 5%, 10%, 15% and 20%. This paper explores the rolling and sliding of the composite gears running against nylon gear with a simplified method of analyzing and understanding the wear and tooth damage. Tests were conducted without external lubrication over a range of loads 4Nm, 8Nm,12Nm and 16Nm using a gear test rig. The test results of composite gears are compared with unreinforced polyester gear (URPE). It was found that the surface temperature was the primary factor affecting the wear rate and an initial relationship between gear surface temperature and load capacity. This composite can be useful for automobile and industrial applications.

Effect of load and speed on warship power rear drive system helical gear anti-scuffing properties in thermal elasto-hydrodynamic lubrication

The key parameters which caused the scoring failure of helical gears are operating load and speed. In this study, the simulations using geometric meshing theory were carried out to investigate the effect of load and speed of warship transmission helical gear system on thermal elasto-hydrodynamic lubrication. The numerical algorithm for the analysis of three-dimensional thermal elasto-hydrodynamic lubrication used in this work has advantage that the film pressure and distributions can be calculated from Reynolds equation for all mixed lubrication regions without any specific boundary condition for the edge of solid contact region. Oil film pressure, film thickness as well as film temperature under different load and speed conditions were obtained and compared. In addition, experimental tests were conducted to determine gear surface temperature under different load and speed conditions. This work provided a guidance to understand the load- and speed-dependent thermal elasto-hydrodynamic lubrication.

Gear surface temperature monitoring

Frictional heating from rolling and sliding contacts of gear teeth is of extreme importance for monitoring the condition of a gear transmission under its continuing operation. The surface temperature holds the critical information about the condition of a gear. A new power circulating gear test rig with a multichannel computer data acquisition system was built to develop various sensor technologies for gear surface temperature monitoring. In this paper, gear surface temperature monitoring will be presented by using miniature thermocouples. Five miniature type-K thermocouples of 125 μm in diameter were embedded underneath the tooth surface of a spur gear, and real-time surface temperature variations from a wide range of operating conditions were measured. The various effects of load, rotating speed, and meshing point on the surface temperature are discussed. The results attained in this study indicate that the maximum temperature rise occurs on the dedendum, close to the dedendum circle, and the maximum surface temperature difference at the various contact points along the tooth profile was 13°C. Among the various temperature monitoring techniques, the thermocouple is a very reliable and practical means for online gear condition monitoring.