Abstract:

By taking into consideration the advantages and disadvantages of the existing measurement methods of elastohydrodynamic lubrication ( EHL) pressure,a novel measurement method based on the photoelastic theory is proposed,and the corresponding mechanism is discussed. Then,an experimental device consisting of a stereomicroscope,a polarizer,a LED light source and a loading mechanism is developed. The linear-contact fiction pairs of the device consist of an upper polycarbonate disk and a lower cylinder made of GCr15 bearing steel and driven by a DC motor through a synchronous belt. By using a camera mounted on the stereomicroscope,the photoelastic images of the EHL contact region and the polycarbonate disk,which are enlarged 40 times,can be captured,with their fringe grades well reflecting the variations of the lubricant film pressure in the contact region and the inner stress beneath the friction surface. Finally,some experiments are carried out under the load varying from 2 to 50N and at the friction-pair rolling speed of 24,44 and 63 mm/s. The results show that the proposed method is feasible and effective in measuring the lubricant film pressure and the inner stress.

Key words: elastohydrodynamic lubrication, photoelasticity, pressure, inner stress, experimental device