This thesis presents a novel ultrasonic instrument for non-invasive and in-situ
characterization of journal bearing lubricant viscosity. In particular the application to
journal bearings is described by non-invasively measuring the viscosity and localized power
losses throughout operation. This ultrasonic viscometer is based on the reflection of polarized
shear waves from a thin resonating coating layer to increase the measurement sensitivity in
comparison to conventional ultrasonic methods. This instrument allows for a full engine oil
viscoelastic characterization in-situ. The book investigates the effects of temperature
pressure and shear rate and describes in detail the ultrasonic setup and method. Further it
demonstrates that the same technique can be applied similarly to monitor the lubrication of
other engine components. As such it offers a unique instrument that can drive the research of
oil formulations to improve engine performance and fulfill the requirements of international
fuel economy regulations.
