| Abstract: |
The resonant frequency of a sphere in contact with a flat surface was measured as a function of loading force for contacting materials with different elastic moduli. Comparisons were made with predictions based on the Hertzian theory of elastic deformation. With a 4 mm radius, stainless steel ball on a ground stainless steel flat supporting an inertial mass of 180 g, the measured resonant frequencies ranged from 970 Hz to 1.73 kHz as the loading force was increased from 0.85 N to 23 N. This compares favorably with the theoretical predictions which range from 930 Hz to 1.62 kHz. For a 4 mm radius ruby ball on a sapphire flat, where the inertial mass was 200 g, the resonant frequencies ranged from 1.34 kHz to 1.81 kHz compared to a theoretical range of 1.09 kHz to 1.98 kHz as the loading force was increased from 0.97 N to 31 N. |
