A hybrid technique for investigation of elastohydrodynamic lubrication

Abstract: This doctoral thesis deals with a hybrid experimental and numerical method, the so-called Hybrid Technique, to study film thickness and pressure distribution and to investigate the behaviour and properties of lubricants in highly loaded elastohydrodynamically lubricated (EHL) conjunctions. The Hybrid Technique combines experimental studies and advanced numerical calculations. In the experimental part of the hybrid approach Optical interferometry and a Ball & Disc system are applied to obtain the colour intensity images of the EHL contact. The colour interferograms captured by a colour video system are then subjected to image analysis to evaluate the film thickness maps. The pressure distribution is obtained numerically by solving the equation for elastic deformations. Using the Hybrid Technique the pressure and lubricant film thickness in the contact are obtained without making assumptions regarding rheological behaviour of the lubricant. This makes the described approach to a very useful tool in investigations of EHL conjunctions under extreme conditions or in the study of multi-phase lubricants. A detailed description of the Hybrid Technique is given. Different applications of the method are described in study of various phenomena in EHL.