Measuring and testing – Vibration – By mechanical waves
Patent
1984-03-20
1986-01-07
Ciarlante, Anthony V.
Measuring and testing
Vibration
By mechanical waves
G01N 2904
Patent
active
045627363
ABSTRACT:
A ceramic product is exposed to a light from a tungsten lamp, so that a specified region of the product is heated. In this heating process, acoustic emissions from the ceramic product are detected by an AE sensor which is acoustically coupled to the ceramic product by means of a waveguide passage. A temperature gradient directed from the surface toward the inner part of the ceramic product is formed by heating, and thermal stress is applied to the product so that tensile stress is produced in the inner part of the product. In practical use, a crack constituting the core of fracture is caused to grow by the thermal stress, and an acoustic emission is released. The existence of a defect can be evaluated by detecting the acoustic emission. Also, the location of the defect in the product can be detected by heating part of the product. The equivalent crack dimension a.sub.e of the defect is obtained by measuring the rate of production of acoustic emission dN/dt, and the product can be checked for acceptability on the basis of the dimension a.sub.e.
REFERENCES:
patent: 4169662 (1979-10-01), Kaule et al.
patent: 4255971 (1981-03-01), Rosencwaig
patent: 4379409 (1983-04-01), Primbsch et al.
patent: 4430847 (1984-02-01), Quate
Materials Evaluation (Dec. 1970), D. M. Romrell and L. R. Bunnell, "Monitoring of Crack Growth in Ceramic by Acoustic Emission," pp. 267-270.
Journal of American Ceramic Society, vol. 63 (1980), G. S. Kino et al., "Acoustic Surface Wave Measurements of Surface Cracks in Ceramics," pp. 65-71.
Ogneupory, No. 3 (1982), I. I. Nemets et al., "The Possibility of the Use of Acoustic Emission for Investigating the Heat Resistance of Refractories," pp. 144-147.
Iwasaki Hideo
Izumi Mamoru
Ciarlante Anthony V.
Tokyo Shibaura Denki Kabushiki Kaisha
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