Laser-ultrasound characterization of spherical objects. G.L. report No. 5097
- Stanford Univ., CA (United States)
Ceramic bearing balls are desired for high-temperature, nonlubricated use, but because of brittleness, it is important to inspect them for small (1--10 μm) surface defects. Resonance spectrum of a sphere can provide information about its material properties (shear, longitudinal wave velocities); surface wave resonant modes at high frequencies provide information about surface crack density. As surface waves encounter a defect, the resonant energy will be attenuated. By comparing the surface wave mode Quality factors (Q) between a perfect and an imperfect sphere, one can quickly detect the existence of surface imperfection; a single defect will reduce the surface wave resonant Q by about 30%. A non-contacting detection method is presented for measuring resonances of a sphere. A computer controlled system was constructed to excite resonances on a sphere with a transducer by a single Hertzian contact, and an optical heterodyne interferometer is used to detect both amplitude and phase of surface variations on the opposite pole of the sphere. This system can inspect bearing balls with diameters 12 to 1 mm.
- Research Organization:
- Stanford Univ., CA (United States). Edward L. Ginzton Lab.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG03-84ER45157
- OSTI ID:
- 10143768
- Report Number(s):
- DOE/ER/45157--T1; ON: DE94010246; BR: KC0201050
- Country of Publication:
- United States
- Language:
- English
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