Ultrasonic Measurement of Hertzian Contact

摘要

The ability to experimentally determine nonuniform contact pressure without using pressure sensitive films has not been demonstrated in the past. Analytical and numerical models have been used for predicting contact pressure variations, but these are stymied by the lack of experimental tools for verification. This work addresses this short-coming in experimental methods by demonstrating a technique that can measure contacting interfaces remotely and without disturbing the condition of the interface.rnAn ultrasonic technique using measured reflections at a two-body interface has been developed. By utilizing empirical relationships between contact pressure and reflection coefficient, the method is applied to a model system representing Hertzian contact between a cylinder and a flat. The results demonstrate that contact pressure variation over the zone of contact, and length of the contact zone, are measurable. The experimental outcomes are compared to that expected from theory, with favorable correlations. Contact width was measured to be within 30% of theory, while maximum contact pressure was as close as 2%.rnThe information gained from the application of this technique could facilitate understanding of friction mechanisms in dry power transmission or dissipation systems, but it is also applicable to lubricated systems.