Investigation of the tensile strength of liquid squeeze-films subjected to oscillating normal loads
An analytical and experimental investigation was conducted to determine the bond strength of liquid squeeze-films subjected to oscillating loads normal to the plane of the film. A mass with a flat circular bottom was placed on a rigid flat base covered with a thin layer of liquid. A sinusoidal vibration was then imparted to the base, and the acceleration level necessary to break the bond of the liquid film was measured under both atmospheric and vacuum ambient pressure conditions. The effects of a number of variables, in particular the mass, contact area, oscillatory frequency, fluid vapor pressure, viscosity, and surface tension, were considered. Results indicated that liquid squeeze-films can be used to support vibrating loads of considerable magnitude, even in a vacuum environment. The limiting factor on the bond strength was found to be the fluid cavitation pressure which can be negative. An analysis was developed based on Reynolds lubrication theory and predicted accurately the basic trends of the data.