This paper reports the first measurements of the effective tensile strength (or ‘cavitation threshold’), Fc, of degassed samples of a commercial ‘multigrade’ oil over a range of temperatures, T, representative of those encountered under its normal operating conditions (in the range 20°C ≤ T ≤ 140°C). Also reported are the values of Fc obtained for Newtonian silicon oils over a range of shear viscosities. In the experimental apparatus used in this work, samples of liquid are subjected to dynamic stressing involving a rapid pressure-tension cycle (this being a feature of conditions experienced by a lubricant within a dynamically-loaded journal bearing). Moreover, the method used herein to estimate Fc avoids reliance upon direct measurements of substantial dynamic negative pressures using transducers which are designed for use in the range of positive pressures.

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