An Experimental Study of Transient Effects in Elastohydrodynamic Lubrication

Machine elements such as bearings, gears and cams form a key part of almost all mechanical systems including electric motors, wind turbines, internal combustion engines, helicopter gearboxes and EV transmissions to name a few. Reliable and efficient operation of these components is heavily dependent on the existence of thin lubricant films, of the order of 1 micron in thickness, between their rubbing parts. Such films are formed through a phenomenon of elastohydrodynamic (EHD) lubrication. Our understanding of elastohydrodynamic lubrication, and thus our ability to predict EHD film thickness, in contacts operating under steady conditions is well established. However, this is not the case under transient conditions, where the applied load, entrainment speed or lubricant supply changes rapidly. This project aims to use high-speed optical interferometry to investigate the behaviour of the lubricated film under a range of transient conditions.