Measurement of circumferential viscosity profile in stationary journal bearing by shear ultrasonic reflection

Viscosity is the most important lubricant property that affects bearing performance. It controls the film thickness that is established during operation. In this study, an ultrasonic method was used to measure the viscosity profile around a static journal bearing by using shear reflection coefficients. The technique introduced was found to be promising and acceptable results were obtained for certain regions of the journal bearing circumference. It proved to be critical to use the right model for determining viscosity from the layer response to a shear ultrasonic pulse. This study serves as a preliminary work for developing viscosity measurement in a rotating journal bearing.