EHL investigations using a hybrid technique : an experimental and numerical approach

Abstract: This licentiate 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 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 images that captured by a colour video system are then subjected for image analysis to evaluate the film thickness maps from the colour interferograms. The pressure distribution is obtained numerically by solving the equation of elastic deformation. Using the Hybrid Technique the pressure and lubricant film thickness in the contact are obtained without having made any 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. Method is tested out on oil lubricated and grease lubricated contacts. Results are presented and discussed.