| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1994: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1993: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
Dynamic fracture behavior of the ceramics at various temperatures is investigated by using the caustic method together with ultra high-speed camera, heating furnace and dynamic loading device, and moreover, some improvements of the technique of caustics are studied. Consequently, the following results are obtained. (1) Clear caustic pattern can be obtained by preparing the specimen with highly polished surface and by using the specially arranged optical setup. It is shown that the caustic method can be applied for studying the fracture of ceramics under dynamic loading at high temperature. (2) For zirconium ceramics, it is possible to perform experiment up to the temperature of 1200ﾟC by using 2mW gas laser light source and for silicon-nitride ceramics, it is possible to obtain a clear caustic pattern up to 1100ﾟC by using 35mW laser. It is revealed that effects of temperature and loading rate on the fracture behavior are considerably large in zirconium ceramics, but those effects are not so large in silicon-nitride ceramics. (3) A clear caustic pattern can be obtained for aluminum and sialon ceramics by employing multiplication technique of caustics. (4) It is shown that the effect of the size of initial curve on K-value is very small under Mode II loading condition. (5) The visualized pattern based on AE-wave is also obtained and it is shown that this pattern propagated at Rayleigh wave velocity. (6) By introducing the image processing technique, it is possible to improve the accuracy of caustics. Moreover, a simple technique for measuring the elastic constants is proposed. Through this study, some improvements of experimental technique are accomplished and a basic technique for evaluating strength of ceramics under dynamic loading at high temperature is proposed.
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