Failure probability of the ceramics which survived proof test.

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  • 寿命保証試験を通過したセラミックスの破壊確率
  • 寿命保証試験を通過したセラミックスの破壊確率〔英文〕
  • ジュミョウ ホショウ シケン オ ツウカシタ セラミックス ノ ハカイ カクリ

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Abstract

The failure probability of the ceramics in use which are proved their life time by a proof test was studied on the basis of the fracture mechanics of ceramics. Especially the influence of the safety factor, k, for the level of test stress on the probability was studied. The study proved that the probability depends much on the value of n, m, g and k, where n is the material constant connecting the crack propagation velocity v and the stress intensity factor KI as v=AKIn, m is Weibull modules, g is the ratio of the required fracture stress of the ceramics to possess the required life time, σg, to the mean fracture stress, σ, (σg=g·σ), and k is the safety factor or the ratio of the test stress, σk, to σg (σk=k·σg). And it was shown that the probability is the minimum at the optimum value of k, and that the probability can be 1ppm or less at suitable values of k (1.2-1.5), in most ceramics having n-80, m-15 and g-0.5 or less. The efficiency of the proof test, however, is not always so high, especially for the ceramics of low n. Therefore, some care must be paid on the application of the test.

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